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2000 Chevy Blazer Heater Core Replacement

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Old 10-28-2009, 09:05 AM   #1
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Lightbulb 2000 Chevy Blazer Heater Core Replacement

For my first post, I want to paste over a post I did in another forum as I believe it may augment previous posts and help the DIY'er get a better understanding of the Heater Core replacement for the Blazer.

Well, I went and pulled the dash out and replaced the heater core. What I hoped would be a 5 hour job turned into a 17 hour marathon of screws harnesses and vinyl.

I did learn quite a few things while the dash was out and these things may or may not help anyone looking to do the dreaded heater core replacement on their blazers.

I do feel that I need to warn you. There is a good chance that your blazer may be a bit more different than the blazers mentioned in this forum or elsewhere as I have learned, the more options are in the blazer the more harnesses/panels/obstacles you may have to contend with when your pulling the dash out.

I had auto climate on mine and that may or may not make a difference. I have a 2000 blazer LT with tape deck in center console. I could not for the life of me figure out how to take out the damned thing and opted to work without taking it out. I did not remove the seats.

I also did not have to drop the steering column as others have suggested though there were some brackets with four 10 mm bolts connected the dash to the chassis under the steering column that need to be taken out as well as the 2 10 mm bolts under the dash behind the panels: one on each side of the dash assembly (one is accessed behind the glove box on right side). There are also a few 7mm screws to remove on the dash under the speaker panels and defroster panel.

I removed my radio and ac/heat control unit to give more room to reach into the dash and survey things. You may not have to do that. Some have taken the dash out and disconnected it then. I also disconnected the odometer/instrument panel as the dash will come out easier over the steering wheel.

The panels at the bottom aren't too tough to pull out. Just keep checking for screws way back there under the dash if you feel you have them all and it still isn't coming off. You will have alot of panel screws. I kept the screws for each panel with that panel so as to keep track.

Once the dash is loose, you can start looking to see what electrical harnesses you have to remove. The main harness under the blower motor vent behind the glove compartment was disconnected by loosening the 7 mm nut and pulling the 2 blue locking keys out and then wiggling it free. You may also have to unscrew the fuse connected on the driver side as well as the computer OBD-2 connector on one of the panels under the steering wheel.

With everything disconnected, you should be able to pull the dash out. Keep an eye on the driver side as the dash may take out your hazard switch as it swings free of the railing (ask how I know).

Now, some have said that there are 2 10mm bolts to remove behind the passenger side fender and recommend dropping the fendor just enough to get to it. Looking back, I couldn't see a reason to and in hindsight I may have wasted time doing that.

If the heater assembly won't come out and everything else is loose feel free to do that.

Instead, Try to just get the 2 screws on the engine side firewall by the heater core connector (one on the right and one on the left/bottom area besides the evaporator cover) as well as the bolt in the evaporator by cutting and using a ratchet wrench. Keep in mind that there is also another 10mm bolt on the cabin side of the firewall under the heater assembly that needs to come out.

Now here is the part I couldn't find info on and had to wing it. There are two tabs - one on each side of the 10 mm bolt cabin-side firewall under the heater assembly. It seems the bolts can be wrenched loose on the engine side of the fire wall....I never found them. Instead, I tore those bastards loose. Don't do what I did. Use a dremel as you may have a hell of a time getting the heater assembly back in line to get the bolts back in and torn tabs make it all the more harder.

That happened to me and must have added a good 2 more hours trying different ways to get that damned bolt to thread cause the tabs were in the way and would seat right as would a strait rotory cut would have.

With everything loose you should be able to pull out the heater assembly by disconnecting a few choice vacuum lines and some more connectors. The cooling line connectors on the new heater core will have some play so you can get it in there correctly. Make sure that you hook the two vent looking connectors going into the carpet before thinking the heater assembly is working your nerves. For some reason the heater assembly connects to the floor vents which in turn connect to mounts under the carpet.

Now just reverse what you did. Some things to keep in mind.

-The rear wiper/gate open switch wire can and will get caught when you put the dash back in. Keep it loose.

-There is a connector for the actuator motor on top the heater assembly against the firewall. Connect that before you bolt in the dash. I had small fingers and finagled it in by luck and prayer.

-Make sure you connect your courtesy lights for floor lighting back to the panels you took them off of.

-Your passenger side door sensor may or may not have a wire. Try to see if it does before you get started so you don't worry about it and take the dash apart again trying to find it before giving up wondering if it even existed.

-You will need a friend to help put that heater assembly back on the firewall to get all the bolts to thread. You will also need some dexterity to put that one bolt in the evaporator housing back in.

When you have everything back together again hook up your cooler lines to the heater core and open up the radiator cap/reservoir cap. Turn on the engine and make sure you get all the air out of your cooling lines.

The automatic Climate control may need to relearn temp parameters or at least it seemed to the first few drive cycles.

Remember, this was for a 2000 blazer LT 2WD with all sorts of options installed. It may differ just a little from your setup or it may be completely different. Either way I hope all this info I learned and have transferred to this post will help any who doesn't want to pay money to get it done.

Unfortunately, I didn't take any pics. I seriously think I invented a few more cuss words over the course of the repair, But it feels good to have heat for the cold season as well as pride in having no screws left when it was finished!
Old 10-28-2009, 12:33 PM   #2
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Re: 2000 Chevy Blazer Heater Core Replacement

y didnt you just bypass the heater core it took me like five mins to do that and now my truck runs great and stays alot cooler, so i have no heater w/e.
Old 10-28-2009, 12:50 PM   #3
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Re: 2000 Chevy Blazer Heater Core Replacement

While I was researching how to do the replacement, I did have it bypassed.

With the winter coming it was a luxury I wanted to have. Down here in Louisiana, you get a lot of moisture to go with that cold weather and you constantly have to keep your windshield wipers on.

That bothered me to no end. Auto Climate control rawks as well and I didn't want to miss out on that during the winter. Damp cold air sucks compared to nice and dry cold air.
Old 10-28-2009, 01:28 PM   #4
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Re: 2000 Chevy Blazer Heater Core Replacement

Excelent write up even without pictures! I just replaced the heatercore in my wife's Bravada not too long ago and I definately feel you on inventing some never before heard swear words as I went along.

Also for whatever reason the heatercore in my wife's truck ended up being different from the ones that almost every part's store and even the dealer had in stock. Of course like the intelligent person I am I purchesed the heater core before I delved into this project only to find out when it was time to install the new one that it did not fit at all. I ended up driving around for hours to every parts store in the area and I eventually found the right one at a Napa. That definately added a bit of excitment to the whole deal.

The main difference was the one her truck had in it had a rounded curved bottom while the ones all the other stores and even the dealership had in stock had a more squared off bottom and they wound not seat all the way down into the blower box.
Old 10-28-2009, 02:07 PM   #5
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Re: 2000 Chevy Blazer Heater Core Replacement

Strange. I actually had to adjust the cooling lines lower on the heater core to get it to fit myself but didn't really have a problem fitting in the heater assembly as the lines themselves have a bit of play in them to get them lined up (press fitted).

They did sit a bit to the passenger side at the hole in the firewall though and that made things tough getting the assembly back in to thread that damned bottom bolt in.

Glad you found a solution to your problem.
Old 10-28-2009, 02:24 PM   #6
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Re: 2000 Chevy Blazer Heater Core Replacement

Quote: Originally Posted by dreamsteve
Strange. I actually had to adjust the cooling lines lower on the heater core to get it to fit myself but didn't really have a problem fitting in the heater assembly as the lines themselves have a bit of play in them to get them lined up (press fitted).

They did sit a bit to the passenger side at the hole in the firewall though and that made things tough getting the assembly back in to thread that damned bottom bolt in.

Glad you found a solution to your problem.
I had to to that also. However the problem that I was running into was that the heater core did not fit inside of the blower box at all. Like once I put it in there the whole thing sat up agout 3/4" too high and there was no way to even get the cover back on.

Also for what it's worth once I rotated the tubes on the good core to line them up I applied some high temp silicone around where they connect to it.. I figured it was just a little cheap insurance.

Last edited by Slow_S10; 10-28-2009 at 02:27 PM.
Old 10-28-2009, 02:43 PM   #7
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Re: 2000 Chevy Blazer Heater Core Replacement

I didn't think of that. I have this nightmare that my "brand new" radiator cap will fail on me and take my heater core with it. lol that much work and I worry about anything making it bust
Old 10-29-2009, 05:30 AM   #8
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Re: 2000 Chevy Blazer Heater Core Replacement

Excellent write-up and I saved it to Word. I know what you mean when you say that a 5 hour job turned into 17 hours with new vocabulary words. I was stripping out a '98 Jimmy and I found that the dash was the hardest part of the whole vehicle. If no one has ever tore into their dash completely, you are in for a new experience. Measured in "beer time" it was probably a case. LOL!!! I found that the cheap magnetic trays are a lifesaver when it comes to keeping the bolts and screws as there are a multitude of them in the dash.
Again...great write-up!!!
Old 01-30-2010, 08:35 AM   #9
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Re: 2000 Chevy Blazer Heater Core Replacement

Quote: Originally Posted by dreamsteve
What I hoped would be a 5 hour job turned into a 17 hour marathon .
Dayum!! You beat me by 1 hour!!!!
As I recall (2 years ago) it took me 18????
I was very methodical as it was my wife's car (2000 Jimmy/Envoy) with a friggin' cell phone and radar detector all wired in as well.

Quote:
I had to to that also. However the problem that I was running into was that the heater core did not fit inside of the blower box at all. Like once I put it in there the whole thing sat up agout 3/4" too high and there was no way to even get the cover back on.
Yup...a NAPA Replacement part did not fit into the saddle (had squared off corner's where I needed "rounded one's). I had to bite the bullet and spend $180 from the Stealership.


Last edited by jbag; 01-30-2010 at 08:45 AM.
Old 03-31-2010, 08:04 PM   #10
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Re: 2000 Chevy Blazer Heater Core Replacement

I just picked up an after market heater core with the squarish corners. Of course, it didn't fit and the top of the housing didn't fit. I used some CORK TAPE that I had left over from a furnace/AC install I did on my girlfriends houst to seal the top. I'll try to get some pics later, but something to consider/ponder upon for anyone doing this replacement. I spent $59 on the after market and the dealer wants $130. I can't see spending the extra dough on an old truck when the cork tape should do the job.
Old 04-01-2010, 08:41 AM   #11
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Re: 2000 Chevy Blazer Heater Core Replacement

Here are 3 photos that you may find useful.

The top is just another view of the heater assembly pulled away from the firewall.

The middle show how I removed the bolt in the condenser area. I'm almost 6'4" and about 230lbs. I had a bitch of a time trying to finesse my hand to remove the bolt out through the blower resistor cover, so I blew a hole in the front of the housing and used an extension. This took me a whole minute and I should of done that from the beginning instead of wasting over an hour of fail time. I now have the hole patched with corktape and rivited over a piece of plastic. It will work great.

The lower photo shows the ill-fitting heatercore back in the housing with cork tape sealing the top. It's ugly, but it'll work. I'll hopefully never see it again. The photo, for whatever reason, makes it look like a larger crack that what it is.

I hope someone finds this useful.


Last edited by drewbad; 04-01-2010 at 08:42 AM.
Old 04-02-2010, 11:15 PM   #12
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Re: 2000 Chevy Blazer Heater Core Replacement

Quote: Originally Posted by jbag
Yup...a NAPA Replacement part did not fit into the saddle (had squared off corner's where I needed "rounded one's). I had to bite the bullet and spend $180 from the Stealership.
See that's the weird thing... I even went to a dealer and the only one they had had the square corners too. NAPA was the only store that actually had the right one, not to mention it ended up being much cheaper.
Old 01-17-2011, 07:35 PM   #13
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Re: 2000 Chevy Blazer Heater Core Replacement

damn i wish i had seen this before i started my heater core in my 03. would have saved me a lot of time and headaches! NICE WRITE-UP!
Old 06-10-2011, 01:21 PM   #14
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Re: 2000 Chevy Blazer Heater Core Replacement

Does anyone have any more questions im in the process of doing it right now. Took everything apart I have to get every nut and bolt back on. Only took me 4 hours to get the entire dash. heater housing and inner fender off . Next week Ill replace the bad heater core and reinstall . It is really easy.
I did not take any short cuts or cut or break anything, i found every bolt that needed to come off, belive it or not to get the dash out it was only 2 bolts on the bottom and 6 on the top. Then u lift and pull and after everything is unplugged it all comes out! The heater box itself it a little more difficult, There are 10 mm nuts and bolts, 2 nuts which require you to remove the right inner fender and 1 bolt in the a/c box under the hood and one behind the engine. I was able to get at both, the one inside the a/c box after removing the heater relay and the other being very careful.

Old 06-10-2011, 08:24 PM   #15
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Re: 2000 Chevy Blazer Heater Core Replacement

You don't have to remove your inner fender or get those two bolts out. You can pull the top of the heater box off and lift out the core with it still in place. Saves you a lot of time and wasted effort. The only shortcut I took was drilling a hole in the heater box underhood to access the bolt inside instead of trying to do it through the blower resistor hole. You can see the socket extension through the hole. When done I just used a black trim plug I had and siliconed it back in the hole.


Old 08-28-2011, 11:00 AM   #16
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Thumbs up Re: 2000 Chevy Blazer Heater Core Replacement

Thanks to dreamsteve, Zeeke98 i have be motivated to post this video and for the people who need help to understand how to pull out the dash




I put some picture together to help understand how to replace the heater core of a 2000 S10 4.3L

NOTE
1. Mark each and every single screw use your own method or tape the screw with the panel.
2. Lower the shift on L1 so you do not damage anything
3. Safe yourself $800.00 or more
Old 08-28-2011, 03:11 PM   #17
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Re: 2000 Chevy Blazer Heater Core Replacement

I didn't remove my console or drop my column but I have a console shift. I also didn't unplug the door pin switch. It's part of the dash wiring that comes of with the two plugs you showed.
Old 08-30-2011, 03:57 AM   #18
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Re: 2000 Chevy Blazer Heater Core Replacement

Does anyone make a copper core? My 96 Jimmy blew up the core this weekend. I'm getting it fixed now. I bought a new core and it's aluminum. The hoses are crimpped to the core!! WTH??
Old 08-30-2011, 08:04 PM   #19
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Re: 2000 Chevy Blazer Heater Core Replacement

What do you mean crimped to the hose? They just use a rubber hose and a tension clamp. The hoses stick to the tubes so you have to work to get them off or slit them to slide them off. All cores are aluminum, there are no copper ones.
Old 08-31-2011, 12:31 AM   #20
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Re: 2000 Chevy Blazer Heater Core Replacement

I mean the tubes are crimpped to the core!! I'll have to take a picture if it's not too late tomorrow. Three crimps to the core for each tube! With that kind of manufacturing, I'll be replacing soon again. I'm trying to find a way to make it leak proof. May use some RTV that high temp. It's flexible enough for the tubes to move with engine vibration. Yet stiff enough to hopefully stop a small leak for a while.
Old 09-01-2011, 09:45 PM   #21
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Thumbs up Re: 2000 Chevy Blazer Heater Core Replacement

Quote: Originally Posted by Zeeke98
I didn't remove my console or drop my column but I have a console shift. I also didn't unplug the door pin switch. It's part of the dash wiring that comes of with the two plugs you showed.
Zeeke98 you are right that was my mistake the door pin is part of the dash wiring
Old 09-01-2011, 11:48 PM   #22
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Re: 2000 Chevy Blazer Heater Core Replacement

I just picked up a delphi heater core at amazon for $40.00
Old 04-28-2014, 11:53 PM   #23
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Re: 2000 Chevy Blazer Heater Core Replacement

Not sure if this is the newest or most complete thread, but seems to have pretty good info for 2nd gen. I just wanted to add another comment that when you put the dash back in, the screws that go in just below the glass (generally the first ones you install when you rotate the dash back into position), make sure they are the screws with the pilot (flat) point (not sharp point).

Other comments based on my recent experience:

Remove the radio and glove box first (makes access to electrical connectors way easier).

Remove the steering column (just makes everything easier).

Although most of us did this without help, the dash is fairly heavy and awkward to handle, so a helper would be useful.

Finally, you will save a TON of money doing this yourself, so even if you do take 17 hours it is well worth it. (I think it would take about 5 hrs the second time around). It really is not that difficult, just that you keep thinking "I can't believe I have to do all this just to get the fricken heater core out".
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