No heat at feet or defroster.

[ZQ8 Blazer]

It's a 98 Blazer and I couldn't find the exact problem I'm having. I did the mod this summer to keep the heat from coming out at the floor. I unplugged the vacuum line the other day and put it back the way it was originally. Now I have a tad bit of hot air coming out at the floor, but it doesn't change if I select the top, floor, defrost, or off, it's still the same amount and no matter what I select 98% of the air will be blowing out of the top (not defrost) vents. The heat and A/C switch between one another very quickly still.

Can anyone think of what this may be? I haven't checked the vacuum lines yet(or anything for that matter), but I just put the defroster on the other day(cold air) and it worked fine.

[laydout97]

Other than checking the vaccum lines, it could be the selector or any of the selector doors under the dash. I bet it's the vaccum lines though.

[Rhotpursuit]

Quote: Originally Posted by laydout97

Other than checking the vaccum lines, it could be the selector or any of the selector doors under the dash. I bet it's the vaccum lines though.

X2...The lines under the hood were crumbling on mine.

[ZQ8 Blazer]

Yeah mine is looking pretty bad. I guess I'll take it off and find out what size I need.

I hope I don't have to take the dash out, I've done it before on other trucks, I just don't want to in cold weather.

[stencer]

Where are these vacuum hoses you're talking about? I'm having the same problem.

[Rhotpursuit]

There is a fitting by the pcv valve that supplies a one way valve, then splits off to the vaccum can and the hvac controls. If I remember correctly the hose sizes are 7/32 & 5/32. Aside from the pcv and brake booster, I didn't find any others under the hood.

[91sonomast]

Quote: Originally Posted by Rhotpursuit

There is a fitting by the pcv valve that supplies a one way valve, then splits off to the vaccum can and the hvac controls. If I remember correctly the hose sizes are 7/32 & 5/32. Aside from the pcv and brake booster, I didn't find any others under the hood.

yeah theres not many vacuum accessories on these 4.3's, my 2.8, holy crap, i think it ran off vacuum. I bet it had 15 vacuum lines

[ZQ8 Blazer]

Fixed it, it was the vacuum hose under the hood. Everything works better now then when I 1st bought it.

[shaynel18]

what about if 1 day u got heat thenthe next nothin, it just shoots out cold air, and of course since i live in effn boston and it was 23 outside 2day it decided to not work any more, what can i do to get my heat back grrrrrrrrrrrr, its told cold here for this shit to happen,

[Rhotpursuit]

Quote: Originally Posted by ZQ8 Blazer

Fixed it, it was the vacuum hose under the hood. Everything works better now then when I 1st bought it.

[Tony H]

Quote: Originally Posted by Rhotpursuit

X2...The lines under the hood were crumbling on mine.

Hi Everybody. Brand new to the Site. Excuse me for this Hi-Jack but the Thread is common to my issue.
Defrost/Feet Selector does not Select, It stays as is no matter how you turn the knob.
I found on the Drivers side right by the Cruise Control Module a Disconnected Vacuum line It's a 6" hose that plugs int the Little white 'one way' Valve. The other end is free hanging. I looked everywhere in that area and cannot find where this connects to. Of course there is no room to look between the Cruise Control and the ABS just in front of it. That's exactly where it is. I don't think this Cruise module needs a Vacuum going to it. If it does I cannot see or feel around for the Nipple. I have a picture that I can send someone if they want to take a look

[GeorgesBlazah]

Im having a brain fart, get a pic and Ill go look at mine.

[ZQ8 Blazer]

Quote: Originally Posted by Tony H

Hi Everybody. Brand new to the Site. Excuse me for this Hi-Jack but the Thread is common to my issue.
Defrost/Feet Selector does not Select, It stays as is no matter how you turn the knob.
I found on the Drivers side right by the Cruise Control Module a Disconnected Vacuum line It's a 6" hose that plugs int the Little white 'one way' Valve. The other end is free hanging. I looked everywhere in that area and cannot find where this connects to. Of course there is no room to look between the Cruise Control and the ABS just in front of it. That's exactly where it is. I don't think this Cruise module needs a Vacuum going to it. If it does I cannot see or feel around for the Nipple. I have a picture that I can send someone if they want to take a look

send pic to zq8_blazer@yahoo.com

If you're talking about what I think you are then that piece missing should go to a sphere shaped vacuum resevoir inside the fender or it's attached to the hood. One of the hoses were running parallel to the drivers fender and the other was running parallel to the firewall and was right up against it too. They both come to a "T" fitting the bottom of the "T" is where the hose running parallel to the fender connected and the top left is where the one against the firewall connected. The top right side was missing the hose. I just plugged the top right side and it now works fine.

Also check the hose to make sure it's not dry rotted.

[ZQ8 Blazer]

Here's his pic:


1. is where the sphere should be
2. is what you need to put a cap over(once the hose is removed from this end), Lowe's and places like that has this thing called a "screw cap" I think that's what it's called anyway. It goes over the exposed threads on a screw and it's the perfect size, you could use anything to cap it though that's just an idea.
3. ofcourse this is what attaches to the sphere.

It would be better to hook the hose back up to the ball, but it's a bitch to get to with the fender on. I believe all it does is make the doors on the heater / a/c box move faster at idle, but I could be wrong.

[Tony H]

Quote: Originally Posted by ZQ8 Blazer

Here's his pic:


1. is where the sphere should be
2. is what you need to put a cap over(once the hose is removed from this end), Lowe's and places like that has this thing called a "screw cap" I think that's what it's called anyway. It goes over the exposed threads on a screw and it's the perfect size, you could use anything to cap it though that's just an idea.
3. of course this is what attaches to the sphere.

It would be better to hook the hose back up to the ball, but it's a bitch to get to with the fender on. I believe all it does is make the doors on the heater / a/c box move faster at idle, but I could be wrong.

Sphere? There is nothing there at all on this Blzr. I do not even see any old mounting tabs or anything. Do you have a Pic to send me of this sphere.
After plugging this off (#3) this afternoon, the Heater, defrost doors started working. I wish I knew what I was looking for.

THANKS for posting with teh PIC. I'm sure it will help other too.

[ZQ8 Blazer]

No I sure don't have a pic, I don't have the sphere either, it's a black ball, it's inside the fender towards the cab, it's hard to get to with the fender on. I'll see if I can find a pic of it.

yeah it's fine to plug #3 off too.

[ZQ8 Blazer]

this is the only one I could find, it's at the top right of the screen attached to the hood, you can about 1/2 of it.

I THINK just the 2.2's were attached there. Yours should be inside the fender though.

[Tony H]

Ahhhh, I have seen them on other cars.

I looked all around in that area after your last post. I looked through the cutouts in the Inner fender to see if it was in between. I saw Nuth'n.

It's OK, It's working now and I know what to look for If I stumble onto one. It basically a sealed tank.
Thanks for your efforts

[ZQ8 Blazer]

yep that's what it is and no problem.

[Rhotpursuit]

Quote: Originally Posted by Tony H

Ahhhh, I have seen them on other cars.

I looked all around in that area after your last post. I looked through the cutouts in the Inner fender to see if it was in between. I saw Nuth'n.

It's OK, It's working now and I know what to look for If I stumble onto one. It basically a sealed tank.
Thanks for your efforts

What year is your truck? Some had a ball attached to the underside of the hood. If you have neither, I'd get the ball...much easier to install and replace if you break the nipple...

[kms_dude1]

Quote: Originally Posted by ZQ8 Blazer

Here's his pic:

the vaccum bottle on the 98+ are in the fender. it is right next to the abs module. on this picture number 1 and the arrow is right in front of it. i know mine was unhooked and can be put back on but its not easy. look around there. you will probably see it

[ZQ8 Blazer]

naw I know mine doesn't have it, I replaced the fender and didn't notice that it was on the old one so I didn't swap it to the new fender.

[orangesonoma]

i wonder if this is my problem.. just one day i lost heat on the floor and it only hits the dash vents...sucks...

but i took apart the climate controls and the little hose have suction....does that mena my problem is not this?

[ZQ8 Blazer]

Mine still had a little suction, but not enough. I'd check the vacuum hoses for leaks and/or dry rotting. I believe the ball just makes the doors move faster when the engine is idling, mine works fine w/o it, but seems to work slower when stopped.

['JustDreamin']

The little ball thingy is a vacuum reservoir. Kinda like an air tank, only for vacuum (air tank in reverse). Which is why the doors run better with the ball, not without.

'JustDreamin'

[kms_dude1]

Quote: Originally Posted by ZQ8 Blazer

naw I know mine doesn't have it, I replaced the fender and didn't notice that it was on the old one so I didn't swap it to the new fender.

it should. w.e the truck is wrecked it usually never gets replaced. most over look it. i did until the night i heard a leak. just take a look. the ball that mounts to the hood can not mount on the 98+ since the abs module hits it. just my 2 cents.

[ZQ8 Blazer]

Thanks, but I replaced the fender myself, it's not there.

[orangesonoma]

i looked at the hose today....man thay are all dry rotted...guess that my problem

[ZQ8 Blazer]

Yeah they'll get that way sooner than ya think.

[orangesonoma]

yeah its amazing that my 4wd still works since it is all part of the same system...

how much did you replace?

[Rhotpursuit]

Quote: Originally Posted by orangesonoma

yeah its amazing that my 4wd still works since it is all part of the same system...

how much did you replace?

There are two sizes...5/32 & 7/32. 1 foot of each is more than enough for both.

[ZQ8 Blazer]

^I think he's talking about the entire 3pc. setup.

Quote:

how much did you replace?

Replace all of the hoses.

Get about 2 ft for the 1st two and 3 for the other long one. Should have some left over. get more if you like it's really cheap. Also get something thicker walled than that cheap OEM shit.

[Rhotpursuit]

Quote: Originally Posted by ZQ8 Blazer

^I think he's talking about the entire 3pc. setup.


Replace all of the hoses.

Get about 2 ft for the 1st two and 3 for the other long one. Should have some left over. get more if you like it's really cheap. Also get something thicker walled than that cheap OEM shit.

Where the hell are your hoses going they need to be that long?? Are you talking about the hoses that go to the transfer case?? The hoses I'm talking about are the ones that go to the vaccum ball and to the smaller hard plastic line that go thru the firewall.

[ZQ8 Blazer]

You're right about 2-3 foot should do it. I thought there was one that ran all the way down from the drivers side of the firewall to the blower box.

[orangesonoma]

if it is cheap i will buy more...but it is two sizes?

[Rhotpursuit]

Quote: Originally Posted by orangesonoma

if it is cheap i will buy more...but it is two sizes?

Yep...

[orangesonoma]

****ing gm...i swear

[vince921]

ha damn i got the same problem... just put the heat back in my truck for the winter.. and only have it on the dash and only blows good when cruising doesnt work worth a shit at idle...

and i have vaccum..



run's outside to check line under hood

[orangesonoma]

Quote: Originally Posted by vince921

run's outside to check line under hood

i did the same thing...

[ZQ8 Blazer]

I got the same size I.D. and used really small zip ties on each end, works fine.

[orangesonoma]

well i just changed out the lines and still no work.. i replaced them all...only one i did not do was the one that goes to the transfer case...i even got it to plug back up to the can thing in the fender...and i tried to plug it...buttt i also changed out the diaphragm in the climate controls itself since they would whistle...and now i think i have a problem with the flab motor thing...cause when i put it on defrost only it blows out the top of the dash and the face vents....wtf...did that make sense?

[ZQ8 Blazer]

I don't know man. When I was having this problem I searched the forum and some people have problems with the doors the change where the heat is blowing and you have to take the entire dash out to fix it, it's a really cheap part I believe, but the entire dash has to come out.

[orangesonoma]

Quote: Originally Posted by ZQ8 Blazer

I don't know man. When I was having this problem I searched the forum and some people have problems with the doors the change where the heat is blowing and you have to take the entire dash out to fix it, it's a really cheap part I believe, but the entire dash has to come out.

well **** that shit...it blows in my face..big deal..lol

[ZQ8 Blazer]

lol

[orangesonoma]

whats funny is all the air come from the face vents....even the air that would come out the feet from the fresh air flow thingie....that sucks..but at least it heats the truck up.. i am not pulling that dash

[ZQ8 Blazer]

Yeah, mine was doing that when it was messed up, I hated it.

[Buddha..]

Well you guys inspired me to fix my heat.

I checked for the vacuum ball, couldn't find it. Wasn't on the underside of the hood. It must be in the fender but I didn't see it. What I saw was a black plastic block-off plate that goes behind the abs thingy. There is a nipple coming off it that the hose goes on. Really really hard to see.

Long story short I trouble shot it for 15min in 0 deg garage, didn't get anywhere. ****ing problem was the line fell of the TB so nothing was getting vacuum.

Works great now though. My toes are numb.

[orangesonoma]

pfft i wish that was my problem

[Tony H]

Quote: Originally Posted by ZQ8 Blazer

send pic to zq8_blazer@yahoo.com

If you're talking about what I think you are then that piece missing should go to a sphere shaped vacuum resevoir inside the fender or it's attached to the hood. One of the hoses were running parallel to the drivers fender and the other was running parallel to the firewall and was right up against it too. They both come to a "T" fitting the bottom of the "T" is where the hose running parallel to the fender connected and the top left is where the one against the firewall connected. The top right side was missing the hose. I just plugged the top right side and it now works fine.

Also check the hose to make sure it's not dry rotted.

Quick question: After you plugged the hose that should go to the sphere, did your 4WD still work?
The 4WD worked a few months ago when my daughter bought this car. Yesterday in the Snow, we push the 4WD Hi and the button lights as we press it but turns off after we let go. This is a shift on the fly 4WD...Yes? we were going super slow when we tried to shift into it. Should the car be in neutral or Park maybe?

[orangesonoma]

Quote: Originally Posted by Tony H

Quick question: After you plugged the hose that should go to the sphere, did your 4WD still work?
The 4WD worked a few months ago when my daughter bought this car. Yesterday in the Snow, we push the 4WD Hi and the button lights as we press it but turns off after we let go. This is a shift on the fly 4WD...Yes? we were going super slow when we tried to shift into it. Should the car be in neutral or Park maybe?

you may have a different problem...it maybe the encoder motor in the transfer case