Heater problem - S-10 Forum
S-10 Forum is the resource on GM S-series trucks, Suspension, engine information, Body Modifications, painting tutorials.  Modifications to suit every need, budget and whim

Heater problem

Go Back   S-10 Forum > Specific Model Forums > 2nd Gen Forums > S10 / Sonoma
New User? Register Forgot Password


 
LinkBack Thread Tools
Old 09-17-2007, 07:47 AM   #1
Registered User
 
Join Date: Nov 2003
Posts: 839
Location: Kansas City
User is: OffLine
Heater problem

Sorry would have searched but need to head to work dont have time right now if any of you guys could help id appreciate it. Im Having problems with my trucks heater/ac. The temp control switch is only switching temps half the time. Sometimes it will work sometimes it wont. I can turn it back and forth from hot to cold and it will not change the temp coming out of the vents. Its random, sometimes just playing with it for awhile will get it to work. Any idea what it could be? Hoping its just the switch. It sucks with KC weather the way it is right now cold in the morning hot in the afternoon!
Old 09-18-2007, 07:28 AM   #2
Registered User
 
Join Date: Nov 2003
Posts: 839
Location: Kansas City
User is: OffLine
Re: Heater problem

i replaced the switch that didnt work. I am thinking it is the blend door actuator, i think its electronically controlled in a 98. Any one have any info on replacing it, searched and couldnt find anything that was really helpful.
Old 09-19-2007, 10:53 AM   #3
Registered User
 
Age: 38
Join Date: Oct 2004
Posts: 173
Location: Steeler Country
User is: OffLine
Re: Heater problem

I am having the same issue, it would work every once in a while and the other day it just stopped altogether, didn't think it was a heater core since i don't smell anything and the carpet is dry, but i would guess that the electronics in that door are probably more expensive and just as much of a pain to replace, i don't even know where to start looking to see if thats it.
Old 09-19-2007, 05:12 PM   #4
Registered User
 
Join Date: Nov 2003
Posts: 839
Location: Kansas City
User is: OffLine
Re: Heater problem

in the engine bay, there is a plate on the black box that the a/c lines run into, has a 4 wire plug coming out of it. take this plate off and you can see the blend door. all you have to do is switch the vent back and forth between hot and cold and see if the door moves. if it does your good. if not, its either the switch or the actuator. I just need to know if there is any way at all to replace it without pulling the dash, and how difficult it is to pull the dash if necessary.
Old 10-02-2007, 09:31 PM   #5
Registered User
 
gump2388's Avatar
 
Join Date: Nov 2002
Posts: 254
Location:
User is: OffLine
Re: Heater problem

mines doing the same thing. seem like if i cut the truck off sitting still i can change it from hot to cold as long as i have the key on. it will go to hot but it wont come to cold. please update this
Old 10-03-2007, 10:02 PM   #6
Registered User
 
gump2388's Avatar
 
Join Date: Nov 2002
Posts: 254
Location:
User is: OffLine
Re: Heater problem

does anyone know where i can get all the stuff to fix it. i wanna change my vacuum lines too while im at it.
Old 10-05-2007, 03:36 PM   #7
Registered User
 
gump2388's Avatar
 
Join Date: Nov 2002
Posts: 254
Location:
User is: OffLine
Re: Heater problem

ok hes the deal on this. i checked into mine and there are little gears in the actuator. they call this a air door actuator and the part number for it is 89018356 my chevrolet place had it in stock and he said they fail often. but his part works from 1996-2006 yukons trucks and everything chevy made. im getting ready to tear my dash apart and fix mine. ill keep u updated.
Old 10-11-2007, 04:11 PM   #8
Registered User
 
Age: 38
Join Date: Oct 2004
Posts: 173
Location: Steeler Country
User is: OffLine
Re: Heater problem

Did the actuator fix your problem? I get no heat all, i am assuming the switch works since if i have it on AC and use the temperature control the fan slows down when it hits 72 or whatever i have it set to, flipping it to heat the air temp is the same. Heading to advance auto shortly hopefully they have it in stock
Old 10-11-2007, 09:20 PM   #9
Registered User
 
gump2388's Avatar
 
Join Date: Nov 2002
Posts: 254
Location:
User is: OffLine
Re: Heater problem

yep fixed it. ur gears might be striped out in the thing. mine was. everyone i talked to said that its common for them to fail. idk
Old 10-16-2007, 09:21 AM   #10
Registered User
 
Age: 38
Join Date: Oct 2004
Posts: 173
Location: Steeler Country
User is: OffLine
Re: Heater problem

How hard was it to replace and what did the dealer charge ya for it, mine is asking about $60
Old 11-20-2008, 03:23 PM   #11
Registered User
 
Join Date: May 2007
Posts: 44
Location:
User is: OffLine
Re: Heater problem

Quote: Originally Posted by 2000_Diamond
How hard was it to replace and what did the dealer charge ya for it, mine is asking about $60
i also im askin, mines doing the same thing everything else seems fine, i just dont get hot air, how hard was it to replace? do u have to take out ur whole dash or can u fix it from the engine bay where that other guy said to take the plate off on top of a/c box?thanks guys
Old 01-20-2009, 10:51 AM   #12
Registered User
 
Age: 46
Join Date: Jul 2005
Posts: 75
Location:
User is: OffLine
Re: Heater problem

How do you get to the actuator? anyone have a quick guide?
Old 04-06-2009, 11:12 PM   #13
Registered User
 
Join Date: Aug 2008
Posts: 95
Location:
User is: OffLine
Re: Heater problem

Update please. How hard is it to replace. How much of the dash needs to come out to reach it?
Old 04-06-2009, 11:58 PM   #14
Registered User
 
Join Date: Aug 2008
Posts: 95
Location:
User is: OffLine
Re: Heater problem

I found these instructions for a 98 s10 blazer.

1. Disconnect battery cable.
2. Open glove compartment, and lift tab in upper left corner to allow the glovebox to swing down completely towards the passenger floorboard.
3. Gently remove the line that enters the "Vac Unit", and then the "Vac Unit" itself by wiggling it upwards off its mount. Once removed gently swing it towards the drivers side and out of your way.
4. You now have access to the Temp Actuator.
5. Carefully remove the electrical connector that feeds the Actuator.
6. Using a 1/4" drive wratchet, and 7/32" socket, remove the two (2) mounting screws. (HELPFUL HINT: For maximum ammount of clearance, Keep the wratchect handle facing the drivers side when putting it in place.)
7. There is no screw on the back mounting post, just a pin that holds it steady.
8. Once you've removed the screws you may need to gently pry the Actuator up off the blend door with a screwdriver.
Installation is reverse of the Removal. The Blend Door and Actuator are both keyed, so theres only one way to put it in. Guide the Actuator onto the Door, then re-secure the mounting screws.
Old 08-03-2009, 11:47 AM   #15
Registered User
 
Age: 32
Join Date: Jul 2009
Posts: 22
Location:
User is: OffLine
Re: Heater problem

I have the same problem, no heat. I have back flushed and changed coolant 2 times. On the second try I was able to unplug the heater core. I have changed the t-stat. I just pulled the blend door actuator. Once removed I plugged it back in to see if it moved when I change the temp and it does. I can move the blend door by hand but its a pretty bulky piece. Maybe the actuator just dont have enough umph to move it. Any Ideas? I hate to throw a $60 part at it that wont fix it. I cant think of ANYTHING else it could be!! Any help is appreciated!
Old 08-12-2009, 08:54 PM   #16
Registered User
 
davelallen's Avatar
 
Join Date: Apr 2009
Posts: 105
Location: winnipeg manitoba canada
User is: OffLine
Re: Heater problem

Quote: Originally Posted by MrPab911
How do you get to the actuator? anyone have a quick guide?
x2
Old 08-17-2009, 10:22 PM   #17
Registered User
 
Age: 32
Join Date: Jul 2009
Posts: 22
Location:
User is: OffLine
Re: Heater problem

read post 14. it tells you exactly what to do.
Old 08-19-2009, 04:03 PM   #18
Registered User
 
davelallen's Avatar
 
Join Date: Apr 2009
Posts: 105
Location: winnipeg manitoba canada
User is: OffLine
Re: Heater problem

Quote: Originally Posted by DevilDogDiesel
read post 14. it tells you exactly what to do.
Yeah but that's a 98 blazer aren't the dashes different than a pic-up and mine's a 97 without ac
Old 10-29-2009, 06:54 PM   #19
Registered User
 
Age: 42
Join Date: Oct 2009
Posts: 1
Location:
User is: OffLine
Re: Heater problem

Thank you for these instructions, they work exactly as mentioned to get to the blend door actuator. But I don't think that is the cause of my problem, just one of the casualties. A brief note of my situation, I have a 98 s-10 pickup. When I got it two weeks ago, I first noticed the a/c didn't work, I could not differentiate between hot and cold air, but all of the vent settings worked. After about a week, it started blowing hot air out of the floor vents all on it's own with the vent setting know turned "off", nothing was turned on at all. After this happened, I lost any control of the vent settings knob that I previously had. This happened the day I took it to the local chevy dealer to have it looked at. Of course, they did a bunch of stuff that didn't fix the problem and charged me for it. After reading this forum, I yanked the blend door actuator and discovered that this unit only switches the door between hot and cold air, it does not switch between the different vent settings. I put the electrical plug back into the actuator and started the truck to operate the hvac controls and the actuator did not move at all. I also noticed that the vent control knob is vacuum controlled, and the a/c compressor kicks in when the knob is turned to max a/c, a/c, defrost/floor, and defrost. I am now thinking that it may be a vacuum problem. Would I be correct in thinking this and, if so, would the problem maybe lay in the switch itself or the vacuum source that feeds the knob? Any ideas on where the vacuum source comes into the dash to feed the vacuum lines that go to the control knob?
Old 12-07-2009, 06:28 PM   #20
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

My truck is not the same as yours, so not sure if this is any help but...

I have an 02 S-10 ZR2. Just noticed the heater does not work. Butt cold here so took it in for a diagnosis. Dealer checked once before and couldn't find anything wrong, so I told them the following, this time:
- engine heats up to normal half way temp
- A/C works
- when selecting heat, only lukewarm air enters the cabin
- when selecting cold, cold air enters
- trying to select vent / def / etc. settings has no effect (stuck on vent)

The shop came back and told me that there is a switch that is mounted under the vehicle, (I think they said on the transfer case), which receives vacuum and routes it through vacuum tubes up into the dash through a series of other switches/actuators. It failed (ruptured diaphragm) and allowed oil to be sucked into the vacuum lines. This oil caused the switches/actuators inline to also fail. They also mentioned heater control head problems as a result, I believe (sorry, going from memory). I could hear a hissing sound from the dash behind the heater controls....

They quoted me $1200 bucks. This would cover actuators and switches and labor. They would blow out/clean the vacuum lines and then replace the electrics.

They said for $300 they could maybe get just the heat to blow hot air but the vent selector would still not work. Is this a problem that you guys with earlier model trucks might be having?
Old 12-08-2009, 09:29 AM   #21
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

I had them replace the switch under the vehicle so that no more oil would be ingested into the vacuum lines and then they flushed the heater core. Now I have heat. The mode selector is not fixed, though. $970 was what they quoted to do that part of the repair.

Not sure why the heater core needed to be flushed. The vehicle was serviced last winter and the coolant was flushed - or so they say.
Old 12-26-2009, 02:26 AM   #22
Registered User
 
Gregs93S-10's Avatar
 
Join Date: Feb 2004
Posts: 16
Location: Ocean Springs, MS.
User is: OffLine
Re: Heater problem

Quote: Originally Posted by shuriken
I had them replace the switch under the vehicle so that no more oil would be ingested into the vacuum lines and then they flushed the heater core. Now I have heat. The mode selector is not fixed, though. $970 was what they quoted to do that part of the repair.

Not sure why the heater core needed to be flushed. The vehicle was serviced last winter and the coolant was flushed - or so they say.
Shuriken,

Check this out...this MAY save you a ton of money...

- Open your Glove Compartmernt.
- You should see a GRAY vac tube right in front of you and an Orange vac tube just to your right going towards the blower area.
- If so, check the GRAY vac tube...is it on the @ 2" round vac actautor?
If not...this is your problem...place the GRAY vac tube back onto the black, round actuator. If it IS on the actuator in fron of you....then watch the metal rod...slowly turn your MODE switch to various positions...does that metal rod move at all? It should if you have proper vaccuum. If the rod is NOT moving, then of course, you have another vaccuum issue.

I hope this helps.
Old 12-28-2009, 01:51 PM   #23
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

Quote: Originally Posted by Gregs93S-10
Shuriken,

Check this out...this MAY save you a ton of money...

- Open your Glove Compartmernt.
- You should see a GRAY vac tube right in front of you and an Orange vac tube just to your right going towards the blower area.
- If so, check the GRAY vac tube...is it on the @ 2" round vac actautor?
If not...this is your problem...place the GRAY vac tube back onto the black, round actuator. If it IS on the actuator in fron of you....then watch the metal rod...slowly turn your MODE switch to various positions...does that metal rod move at all? It should if you have proper vaccuum. If the rod is NOT moving, then of course, you have another vaccuum issue.

I hope this helps.

I will check that out and post back. Thanks for the tip!
Old 01-01-2010, 06:10 PM   #24
Registered User
 
01extreme69's Avatar
 
Age: 32
Join Date: Jan 2005
Posts: 8
Location:
User is: OffLine
Re: Heater problem

I am having the same issue in my 98. Heat only in face and no control to other vents. I noticed there was some line running on the passenger side of the t-case that was burnt by my exhaust. Does anyone know if this could be my problem? I thought at first it was just a vent line from the tranny or t-case at first, but I dont think that anymore.
Old 01-02-2010, 11:44 AM   #25
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

Quote: Originally Posted by 01extreme69
I am having the same issue in my 98. Heat only in face and no control to other vents. I noticed there was some line running on the passenger side of the t-case that was burnt by my exhaust. Does anyone know if this could be my problem? I thought at first it was just a vent line from the tranny or t-case at first, but I dont think that anymore.
I would bet you have the same problem. If the line is burnt through, you won't have vacuum pressure to the heat selection controls. Hopefully yours didn't ingest oil. See if you can replace the line?
Old 01-02-2010, 08:17 PM   #26
Registered User
 
01extreme69's Avatar
 
Age: 32
Join Date: Jan 2005
Posts: 8
Location:
User is: OffLine
Re: Heater problem

I will be looking at it soon. If it got oil, what do I need to do to fix it?
Old 01-03-2010, 02:06 PM   #27
Registered User
 
Age: 59
Join Date: Jan 2010
Posts: 1
Location:
User is: OffLine
Re: Heater problem

I am chasing two problems on my son's 97 blazer. Heater problems similiar to those described here; heater has warm air but only comes out strong on defrost, won't switch to lower vents and the other problem is it won't shift to 4wd. Does anyone think those could both be caused by loss of vacuum?
Old 02-14-2010, 06:32 PM   #28
Registered User
 
Join Date: Feb 2010
Posts: 2
Location:
User is: OffLine
Re: Heater problem

I'm having similar problems on my 97 s-10, noticed that when i turn the selecter on cold... i have suficiant air flow... when turned to heat... little air flow! The air selecter commands seem to work (floor heat, defrost...ok). Would appreciate diagrams or plans of dash underside to find problem.
Thanks for helping,

maed68
Old 10-11-2010, 11:03 PM   #29
Banned
 
Age: 37
Join Date: May 2010
Posts: 18
Location:
User is: OffLine
Re: Heater problem

is the blower motor running? or is it just not blowing hot air? When it comes to the performance of your air conditioning system, you simply can't settle for anything less than high-quality equipments? Once you do, this system's overall functionality will go down the drain. One of the parts that need to be in good working condition at all times is the heater door lever.
Old 11-05-2010, 10:08 PM   #30
Registered User
 
jbobyack's Avatar
 
Age: 34
Join Date: Jul 2010
Posts: 8
Location: Hillsboro, KY
User is: OffLine
Re: Heater problem

I experienced similar problems in my 02' 4.3L Crew Cab 4x4....When selector switch turned to heat, cool air would come through vents. Change selector switch to cold and colder air would come out. Fan will operate at all speeds. Temp guage is about 200degrees after truck warms up, checked blend door---operates when cold-heat selector switch is operated. Metal rods will operate the floor to face feature fine (key has to be turned on) Checked all vacuum lines under truck. Disconnected the vacuum lines that were in the glove box, reconnected after about 30 seconds. Flushed heater core---disconnected lines from motor side (not firewall) We now have HEAT. Trouble shooting took about 45min. flush took only 25min. Thanks for the info.
Old 11-25-2010, 04:41 PM   #31
Sure why not.
 
rhygin's Avatar

 
Age: 28
Join Date: Nov 2005
Posts: 2,202
Location: Vancouver, WA
User is: OffLine
Re: Heater problem

Quote: Originally Posted by shuriken
The shop came back and told me that there is a switch that is mounted under the vehicle, (I think they said on the transfer case), which receives vacuum and routes it through vacuum tubes up into the dash through a series of other switches/actuators. It failed (ruptured diaphragm) and allowed oil to be sucked into the vacuum lines. This oil caused the switches/actuators inline to also fail. They also mentioned heater control head problems as a result, I believe (sorry, going from memory). I could hear a hissing sound from the dash behind the heater controls....

They quoted me $1200 bucks. This would cover actuators and switches and labor. They would blow out/clean the vacuum lines and then replace the electrics.

They said for $300 they could maybe get just the heat to blow hot air but the vent selector would still not work. Is this a problem that you guys with earlier model trucks might be having?

Ive delt with this before a couple times if you do it yourself it just takes a little ****in with and a 30 dollar switch thats on the tcase... It does make a hell of a mess though... Everything fills with tranny fluid or whatevers in your tcase you have to take all the lines off replace them or drain them it ****s up all the actuators and fills em up with fluid stupid design for sure. You can get the fluid out though just takes a little well alot of taking stuff apart. When I was a fleet mechanic and I was getting paid by the hour but working hard it would take me about 6-8 hours to properly clean all that shit out, but working for flat rate I probably would have taken 3-4 just wouldnt have been as good a job. Depends how much fluid gets into the system as well.
Old 09-29-2012, 08:50 PM   #32
Registered User
 
Age: 31
Join Date: Sep 2010
Posts: 23
Location:
User is: OffLine
Re: Heater problem

I realize this is an old forum but I figured I'd post up my experience with my heating problem. I've spent a couple weeks tracking down different issues I thought might be the probelm, but today I fixed it. I couldn't figure out why it wouldn't heat up. I checked everything I could find without taking out the dash. So today I went to the salvage yard to look at trucks that were already taken apart and see If I could figure anything out. I did. I noticed there was one door on the vents that was electronically controlled and was just out of sight. I took a photo.

Heres another photo with the black box removed.


Its kinda hard to tell where this is located. Basically when you open up the dash. You'll see the diaphram with the orange line going to it. Follow the metal piece attached to thetop. Then right above that there is a small black box that controls the blend door. I had worked on my dash a while back and took the dash out. When I put it back in I forgot to plug in that black box. I hooked it back up today and now have heat.
Old 10-04-2012, 03:26 PM   #33
Registered User
 
Age: 44
Join Date: Oct 2012
Posts: 2
Location:
User is: OffLine
Re: Heater problem

First off, thank you very much to all of the people who have posted their ideas and suggestions about this topic. It has saved me a lot of time and money! I just wanted to post about my experience with the "No heat" problem with 98-02 Sonomas.

I bought a '99 Sonoma earlier this year for my son. It has had 3 previous owners, so I really have no idea how well it has been maintained. About a week ago, my son complained that the heater and defroster weren't working. (We are in Boise, ID, so the nights are starting to get nippy this time of year) I got online and started going through these threads. Here is what I did to solve my problem, start to finish:

1) I checked the blend door actuator to see if it was working. I did this by opening up the glove box and releasing the springloaded catch, which allows the glove box to swing all the way down, giving me access to the area behind it. You can then see the blend door actuator sitting on the top right side of the heater box. With the key in the "On" position, turn the heat control from full cold to full hot. As you do this, shine a flashlight on the blend door actuator, specifically on the rod the actuator is connected to, which goes directly down into the heater box. Make sure this rod is actually turning. If it is not turning, chances are you have a bad blend door actuator. (You can change this actuator without removing the dash, but it is tricky. See some of the other posts here about how to do that.)

2) Going under the hood, I removed the blower motor resistor. This part is located just to the left of where the heater core water hoses go through the firewall, on top of the black plastic case (not sure what this piece is called, but you get the idea). When you remove the resistor, you can actually see the blend door. Once again, with the key in the "On" position, turn the temperature control knob to full cold. Note the position of the door. Then turn the temp control knob to full hot. If the door has moved, you know that part of the system is intact, and the blend door/actuator are working and doing their job. (If you move quick enough, you can actually see the door move. Or you can just have someone else turn the knob while you watch- that way, you don't have to put down your beer)

3)The next thing I did was take the truck down to Meineke and had the radiator fluid changed and the system flushed. I could have done this myself, but I didn't want to deal with the hassle, cleanup, disposal of old fluid, etc. Apparently, the fluid hadn't been changed since the truck was brand new. The manager said the fluid was in the top 10 dirtiest radiator fluids he had ever seen! I asked if he flushed the heater core directly, and he said he hadn't because their machine couldn't hook up directly to the heater core connections. (I think this is BS, but I haven't seen the machine, so...) Anyway, he told me to run the truck for a couple of days and see what happens. He also quoted me a flat $1000 to change the heater core, if required. That seems in line with what everyone else is saying here.

4) A few days later, still no heat. So I decided to flush the heater core directly myself. I did this by following the water hoses from the heater core to their connection points on the engine block. I disconnected them from the block, and then took a garden hose with spray nozzle attachement and sprayed first into one hose, allowing the water to flow freely out the other end, and then doing the other hose. I got quite a bit of orange junk (solidified Dexcool) out of there the first couple of times. I then did each side again, this time pulsing the spray nozzle in short bursts to get more pressure through there. On one of these pulses, a BIG batch of hardened Dexcool came out. After 6-9 times of doing this, I reconnected the hoses, refilled the coolant, and started it back up.

I decided to go for a drive to help the coolant warm up faster. During this little test drive, the temperature gauge started climbing past the normal midrange. I didn't want to be caught too far from home in case of an overheat, so I went back to the house. I stopped out front, and let the engine idle. The temp gauge continued to climb up to just short of redline. It stayed there for about 2 minutes, and then suddenly dropped right back to the normal midrange. During this whole test drive, the heat would come and go, but would never remain steady, hot or cold. I was thinking that I didn't have the problem fixed. Then, after the temp went up to redline, hung there, and then came back down, the heat started coming out full bore!

Ultimately, I think it was just a clogged heater core (which, when the junk came loose, got temporarily hung up in the thermostat, causing a near overheat). This has fixed the problem for now, but I'm sure I've got a heater core change coming in the future- hopefully a few years from now. But, armed with the knowledge from this chat board, the job will be a cakewalk.

Once again, thank you to all of the people who have posted on here. It is really cool to see regular people helping other regular people, and keeping us all from getting screwed by the dealerships!
Old 10-24-2012, 12:42 PM   #34
Registered User
 
Join Date: May 2012
Posts: 1
Location:
User is: OffLine
Re: Heater problem

Thanks for the write up wrench! I am dealing with the same issue on my 02 S10 right now.
Old 11-14-2012, 06:58 PM   #35
Registered User
 
Join Date: Feb 2012
Posts: 18
Location: AZ
User is: OffLine
Re: Heater problem

Thanks for the write up! Saved me a lot of time and money all was just as you said after I put in the new actuator I opened up the old actuator and found the small worm drive on the motor had split.

Thanks again, I owe you a beer or 2!
Old 11-20-2012, 01:40 AM   #36
Registered User
 
sistoz11's Avatar
 
Join Date: Apr 2012
Posts: 16
Location:
User is: OffLine
Re: Heater problem

had same issue on my 2003 s10 ZQ8 4.3L no heat and everything checked out fine. first i checked passanger side for any leaks indicating heater core leakage no wet spots found. if wet on passanger side near firewall your heater core is obviously bad causing your heater not to work. if also wet you can bypass the heater core to avoid the spill on passanger side by identifying both heater core hoses and buying a prestone flush kit which will have the same tubing size adapter for your in and out hoses.

check your coolant levels to make sure its topped out to make your cooling system work properly and avoid any air in the system which migh cause heater not to work. do this by topping it out with coolant/water when its cold let it idle with radiator cap off and or use a jack and lift the front end as high as safe as you can with parking brake on and chalk block bilaterally on rear tires. this will hopefully allow any trapped air to reach high point. fill it up and every morning before starting your s10 have water handy and top it off repeatly for 5 days or more.

i checked both my heater core hoses to identify its temperature. intake hose should be hotter than the out as the hot water gets hot on engine side before going to heater core thus providing you with heat through your vents after passing heater core. out hose shouldnt be as hot as the intake hose.

i checked all my fuses should be first but anyway fuses were fine, replaced thermostat which may cause a blockage if thermostat aint fulling opening. its cheap and easy to replace most of them come with the seal already to prevent any leaks, but i bought a water pump, themrostat sealer which can be added but add it lightly.

removed 3 screws which is the the blower motor resistor which gives speeds to your blower motor. these three screws that screw the resistor are sitting on top of your HVAC system. after removing youll see the heat blend door actuator. at this point change your heater from cold to hot and identify its movement. if its moving than it is operating and you dont need the blend door actutor.

open up glove box by pushing up on a spring loaded hook thats located on the left side of glove box if your facing the windshield. push that up youll open up the entire glove box giving you access to view your blower motor and vent doors. make sure doors are opening and closing. theres two on passanger side and one underneath steering column use your phones video to view as your head wont fit to view. if your blower motor isnt working than you need to replace either blower motor resistor or blower motor itself. i would replace blower motor resistor first since its cheaper. remember resistor is those three screws on top of HVAC system. if blower motor only works on high replace resistor as well. if replacing resistor doesnt work replace blower motor youll need to remove a couple bolts from right side fender to flare it out and anti freeze reservoir to work comfortably and to have room to remove blower motor. make sure they sell you the right part. if your blower motor has a tube attached to it make sure new one has the same plug connection. the more expensive ones have the tubing connector on it.

try flushing your heater core with CLR. i did this but it didnt fix it, but it might work for you. look up flushing heater core on youtube.

after looking at everything that might be wrong on why my heater aint working and scratching my head confused as to what it was it ended up being my heater core. I HIGHLY RECOMMEND you flush out all that red crap out of your radiator called DEX-COOL (grey bottle) some how chevy promotes this piece of shit liquid saying it will last you 150,000 miles etc.. but all it does is give you plaque blockages as it did to mine. it also leaves flakes floating around your cooling system. ever notice your radiator cap filled with red gunk. Seriously chevy promotoes this crap to have you visiting their repair shop in the future to replace that heater core which cost nearly 1000 with labor. Flush this out and use prestone (the green coolant)

after flushing my radiator 4 times in a 10 month period ive decided to replace my entire cooling system because dex cool was still present, but the damage was done
as it clogged up my heater core preventing heeter to work.

just thought id give you my experience with dex cool and to seriously stay away from it. after replacing heater core and everything checking out to be working fine i finally had heat working and im living happily ever after.

Hope this helps those that are going through this. they say its a pain removing your dash board but after doing so it really aint as difficult as they say. It just takes time. i suggest you have your own system down as to keeping track of where the screws go etc.. i had full size sandwich zip lock bags and for every different screw i removed i would write on bag and give its location description and some even a diagram. i also kept all the screws with the same part. check out these videos for possible models from 1998-2003 theres 2 parts
Old 12-01-2012, 10:19 AM   #37
Registered User
 
Age: 51
Join Date: Dec 2012
Posts: 1
Location:
User is: OffLine
Re: Heater problem

I read a bunch of forums about this problem and found there are alot of idiots out there as well as poor spellers, typers and troubleshooters.

My issue was I had hot air blowing from the front dash and very little on the floor and defrost. So don't tell me to flush my radiator or heater core or add Bars leak.

I know from this thread how to remove my dashboard, but before going that direction I decided to check the easy stuff first. The vacuum line on the top of my firewall was perfect, but on the side of the brake vacuum booster the two small hoses were totally dry rotted. I keep my vehicle clean, even under the hood, so I was very surprised to see this. So before creating a ton of dash squeaks and wasting 8 hours, take two minutes to check the hoses.
Old 12-01-2012, 11:47 AM   #38
Registered User

 
Join Date: Apr 2011
Posts: 460
Location:
User is: OffLine
Re: Heater problem

Amen, brother.
Old 12-20-2012, 03:51 PM   #39
Registered User
 
Age: 42
Join Date: Dec 2012
Posts: 3
Location:
User is: OffLine
Re: Heater problem

So my problem is no heat from defrost to floor stays on defrost so is there a motor to make the blend door switch or should I look at these vaccines mines a 99 pickup??
Old 02-22-2013, 03:30 AM   #40
Registered User
 
sistoz11's Avatar
 
Join Date: Apr 2012
Posts: 16
Location:
User is: OffLine
Re: Heater problem

Oh Excuse me you expert beat it and your disciple aa21830. this forum is for those who clearly want to gain an inside knowledge of experiences and save others money. if it didnt apply to you as it doesnt since you aint the one who began this thread than dont state your negative feedback. this clearly dont apply to you if your not wanting to flush out your radiator than dont im glad you know how and im glad you know how to remove your dash board. this forum is built on giving ideas and solutions. some work some dont. everything should be considered when one does not know a single bit. one forum in itself might not give you enough information, but we try. only you know what route to take from constant research to eliminate the problem. back up dont tell me you know your shit when my entire intentions are for those who dont know a bit and resources can be as easy as a click away. by the way what hoses should we check? theres many hoses under my hood. exactly my point be direct and precise to get the least experience reader a boost rather than dogging, moaning with zero info. except oh yah check your hoses? all you check your hoses. wish i can slap you with my hose.
Old 10-16-2013, 10:53 AM   #41
Registered User
 
Age: 35
Join Date: Nov 2005
Posts: 13
Location: Fort Worth, TX
User is: OffLine
Re: Heater problem

Well besides the crying and moaning at the end of this thread, this is one of the most informative I've ever read. Wrench69...I really appreciate your write up. I plan to take a look at my heater issue as soon as I have an hour or so and a beer to spare.

I will update here.


Thanks.
Old 12-08-2013, 12:41 AM   #42
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

The thread that won't die! LOL

I'm back. Since acquiring and driving other vehicles, I haven't worried much about the 02 S-10 for awhile. But now it's cold again and this truck, with good tires, is great in heavy snow. So I've been driving it a bit again lately and that means thinking about the heater problem I never spent time on.

I had been resigned to just getting a portable defroster/heater and forgetting about repairing the truck until I realized that the wimpy little heaters designed for 12v systems only draw a max of about 300 watts, which when converted to heat, is barely enough to defrost a small portion of the windshield. Nearly all of the reviews I've seen of them are poor. I thought about rigging up some batteries to provide 24v, but even at that, the 24v heaters only draw about 600 watts, which still amounts to only half of the wattage of a hair dryer or a small space heater.

Long story short, I've almost given up on the defrosters and might tear into the truck.

I reread this thread and spent some time looking at other threads around the net. The story with my truck is that the transfer case vacuum switch failed (according to the dealer), which almost certainly allowed enough oil to be ingested in one or more vacuum lines. While 4-wheel drive works, the HVAC control unit does not work and there remains a hissing sound in that area. I have assumed that the control module must be faulty. Because it operates by vacuum, it is possible that oil made it through the lines to that unit.

It's not my first concern because I want to see what I can do without tearing out the dash. Also, supposedly, if there is a vacuum failure, the system should fail to a mode selection of heat and defrost. This is a functional mode. It may also be possible to close the vents to assist in maximizing airflow in this failsafe mode.

So before tearing into the dash, I had a look at a couple of things mentioned in this thread and others.

1. Blend door actuator, rod, and door. I opened the glove compartment and operated the hot/cold selector and could hear an electric sound but could not see the metal rod moving, and consequently, the blend door doesn't seem to move.

2. In the engine compartment with the hood open, on the drivers side between the brake master cylinder assembly and the fender is a little plastic connector that joins vacuum hoses together. This is a common point for vacuum hose deterioration and sure enough, I found some hose in very poor condition. I am not sure yet if it is leaking there but it will fall apart if I wiggle it very much. Take a look here at about 3:40:

So tomorrow I will try a couple of things. First thing will be to run the truck until it reaches normal temperature. Then I will turn the temperature control to hot. Next I will manually move the blend door actuator rod by hand to see if I can get proper heat in the truck. If I can get proper heat, I will see what I can do to fix the blend door issue. It will defrost somewhat with proper heat, even if the mode controller is faulty. If I still can't get heat, I will try flushing the heater core again.

Additionally, I will replace the vacuum hoses that are obviously bad. If when replacing the hose I find oil in the lines, I know oil has been drawn at least up to that point and probably further. I could probably disconnect the vacuum switch at the transfer case and blow compressed air through and see if I could eject some oil. However, my guess is that oil already damaged the HVAC control and one or more actuators.
Old 12-08-2013, 01:40 AM   #43
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

Just found this VERY informative link that others probably already know about but that I just discovered:
http://www.john-stichnoth.com/SonomaT-caseSwitch.html
Old 12-08-2013, 11:47 PM   #44
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

Spent 10 minutes typing a lengthy reply and session timed out....

So... there are 2 actuators behind my 02 S-10 glove box. The one with the orange hose seems to be a recirculation actuator. I've observed that it functions. The orange hose also has vacuum pressure.

The other, connected by a grey hose, worked one time and wouldn't work any other times. When it did work, normal air flow was directed up to the defrost vents. I was excited to see that but can't get a repeat. There is vacuum pressure on the grey hose.

On the vacuum coupler ports, I have measured about 17+ inches of vacuum on the port block - I think from the black hose, which I assume to be the main feed. I was hoping to see 17-22 but am not really sure what the spec should be.

It looks like one side connects to the HVAC module. Probably the black feeds it and is switched to various other hoses.

I can warm the truck up to 195 in reasonable time so it would seem that the thermostat and water pump are working. However, the upper radiator hose doesn't feel very hot and neither do the heater core hoses. However, they are the same temperature. Coolant level is normal.

When I select heat in the HVAC module, I get lukewarm air. If I select cold, I get cold air. Why do I have 195f coolant and lukewarm air? Bad blend actuator? Can someone confirm where that is located on my truck again? One of the ones behind the glove box (that worked only one time) would seem to be either the defrost vent control or the blend control.

Next chance I get I am going to apply separate vacuum to any actuators I find (except 4wd, which works). I hope to find a leaky actuator rather than leaky o-rings in the HVAC module.

Any help is appreciated.
Old 12-09-2013, 02:14 AM   #45
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

If I'm not mistaken, it looks like the HVAC module can be replaced without taking the entire dash out - as in the same procedure as removing the radio....
Old 12-10-2013, 02:15 AM   #46
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

I removed the dash trim and was able to get to the HVAC module within 10 minutes. I removed it and found ATF in the ash tray and in the HVAC module.

I ended up disassembling it and cleaning everything but I'm not sure how to test it. There is one large flat rubber washer/oring just behind the mode switch. It is grooved in a certain way so that when you turn the switch, it allows vacuum to switch to different outlet hoses. The washer is pressed against a plastic peice by a flat metal washer. Pressure comes from a small spring.

ATF was everywhere but the washer/gasket looks fine. I thoroughly cleaned it and reassembled the module but am not sure how to test it now. If anyone knows which hose should receive vacuum when a given mode is selected, let me know.

If the rubber was damaged by ATF, it isn't visible. The only thing I can speculate on is that maybe the washer has expanded just a tad, causing a slight waviness, which means it doesn't seat exactly right on the metal washer; if that is the case and the spring can't push it exactly flat, it might leak.

If I apply vacuum to the black hose and cover the other hoses, I hear a hiss behind the switch. I was hoping not to. Maybe not testing right.
Anyway, it's convenient to clean and test on the vehicle because if anymore ATF is drawn up to the switch, at least the brand new one isn't going to get gunked up.

Another test I will do tomorrow is apply vacuum behind the glove box on the hose block and see if all of the actuators work.....
Pics later...

There is a number on the o-ring but my web searches turned up nothing: 233132
The number on the mode switch itself is 98923-22 but I couldn't find it online either.

I'm sure just that mode switch could be replaced. Maybe someone can help me locate one with those part numbers.

Otherwise, RockAuto has an HVAC module for about $75. Dealer quoted $150.
Old 12-10-2013, 04:45 PM   #47
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

The good news is that I tested all of the lines and they are holding vacuum pressure.

I was not able to draw fluid into the MityVac cup.

I expect a new control module to fix the problem.
Old 12-14-2013, 01:53 AM   #48
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

Well, I disconnected the transfer case switch hoses and blew air through them from under the hood. A negligible amount of oil came out of that section of hose. I can't seem to get much oil out of the other lines, either.

Tomorrow I will look at the 4wd actuator and see if it's junked up. I will also check the 2 actuators near the gas pedal. I discovered that the slave valve actuator behind the glove box was leaky/bad. When I looked inside at the diaphragm, it had oil inside.

So far I've had to replace the switch (dealer did that 2 years ago), the HVAC control head/module, and the slave valve actuator. I suspect I'll have to replace additional actuators.
Old 12-15-2013, 01:57 AM   #49
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

The good news is that it isn't hard at all to get to the mode and defrost actuators under the dash near the gas pedal. Not even too bad to disconnect and test them.

The bad news is that both show evidence of transmission fluid contamination. One dripped a little when I removed it. They both do hold vacuum pressure and seem to work but replacing them is the best option to avoid recontamination of the lines.

Also removed and tested the 4WD actuator and it works fine. I couldn't get any oil out of it but was able to get just a little oil out of the 4WD actuator line.

So right now I think I'm looking at replacing 3 actuators; already received the new control head.

Not sure as to the best way to clean the lines but if not some combination of soapy water, perhaps brake cleaner and lots of air.

The two main problems I have run into is finding a good source for the actuators and getting access to the last actuator deep in the center of the dash, which could also be bad.
Old 12-18-2013, 02:33 AM   #50
Registered User
 
Join Date: Dec 2009
Posts: 40
Location:
User is: OffLine
Re: Heater problem

I have ordered 4 in-dash replacement actuators and also the 4wd actuator. Tried to order a new vacuum tank but they are discontinued. I have blown out all of the vacuum lines and was only able to expel a small amount of oil. Parts should arrive this week. About $200 in parts, which includes the HVAC module.
Sponsored Links
Advertisement
 

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the S-10 Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 09:58 AM.

Powered by vBulletin® Copyright ©2000 - 2011, Jelsoft Enterprises Ltd. SEO by vBSEO 3.2.0
SEO by vBSEO
vBulletin Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.