So This only Happens when I turn my heat on or put it on vent. Everything's fine for lets say 10 mins. Then 'll notice a lil bit of smoke coming from behind the heat ac controls. Then there's a funny smell. Doesn't smell like something is burning its just funny smell-in. I cant relate it to anything I've ever smelled before.

Now I do know that I have a vacuum leak behind the dash somewhere (When i turn the heat to the off position after its been on I hear a sound as if air is being release somewhere behind the dash).. So pretty sure that's a vacuum leak.

So could this vacuum leak have something do do with that? I dont think it should but Someone might know for sure.

Any help would be great. thanks

Kevin

Fyi I and got no answers on this

 

We have the same problem. It's anti-freeze. We have a bad heater core, which is a 6+ hour job to fix.

 

Well being that his is a first gen Craig I wouldn't go jumping to conclusions. It may not be the same problem as yours. Yours in a 2nd gen keep in mind.

To the OP: You haven't provided any info about your vehicle. What are you driving? It makes troubleshooting easier.
Do you have heat? If you do is it intermittent? Have you pulled the dash apart yet to investigate in behind the HVAC controls.

 

Sorry heres the info requested Sisk.
1994 Blazer s-10 4.3 cpfi with rough 80,000miles on rebuild

Yes I do have heat it it always works

I have yet to take off the dash. If you could post a link to a write up on how to take it off it would be greatly appreciated.

Also on a side note. My belts been squeaking lately and I noticed that the pulley below the ac compressor is locked up. ( Anyone know what this pulley is called. I would like to fix it squeaking is damn annoying) I don't know if this is related at all to the smoke from behind the dash or not. But any help on this subject would also be grateful.


Thanks again guys.

 

That vacuum leak you're talking about, is it followed by what sounds like a flap closing? Or a rattle of some kind? Because if that's the case, it's probably nothing to worry about. Mine does that every time I switch between HVAC controls (heat to vent to defrost...). And correct me if I'm wrong, but if there was a vacuum leak, wouldn't things just not work? I know when I had a shop work on my truck they forgot to connect the HVAC control vacuum line and the controls just didn't work.

 

It just sound like a woosh of air kinda like when you let air outta a tire.
last maybe 1 sec then goes away

 

I would say that's normal. It only occurs when you switch between controls right? And if it isn't normal then something's wrong with both our trucks

 

yeah only when it switches. but what about the smoke coming from behind the dash and the funny smell

 

Well that woosh sound should be normal, its how the heat/cold flap and the vent/heater settings are operated - by engine vaccum.

However the smoke would be steam, and it smells sweet smelling. Its probably from the heater core leaking. And its kind of a bugger to change, anyone can do it, it just takes a while to do. You may also notice that the passenger side floor is damp and sticky feeling, or your windows are foggy on the inside in the morning. Up where the passengers feet are there is a large black plastic heater box, the core is inside that. That large box will need to come out. You should be able to find instructions around here for removal of it, or get yourself a Haynes manual for 25 bucks, the instructions in there are easy enough to follow. The heater core itself might be a hundred bucks, and it looks like a small radiator with 2 pipes coming off it. Hopefully its leaking where the hoses attach to the 2 pipes, then you can trim the cracked tips off the hoses and re attach them. Use some vice grips or something to pinch the heater hoses closed under the hood before you go pulling it out of there, it will save you from making a big mess of coolant inside your cab when you remove the heater box.

Let us know if you need a hand with anything.

 

Sisk: true, the stuff comes out our vents, not behind the dash. could be totally different