Any suggestions as to what is causing this HOT air on my right foot? I have tried various temp control settings but no change. Have looked under the dash for a hole or something from the engine compartment....do not see anything. Unable to determine just exaclty where the hot air is coming from....it could be the floor vents...but rather difficult to be driving and checking at the sametime.

Have the floor console and the center dash trim panel out.

This is on an 2002 LS 4dr, 4wd, column shift auto....sorry about leaving that out...

 

Year/model?

Are you saying the hot air only comes when you're driving?

 

Probably a vacuum leak. Vacuum controls the HVAC controls. That or the actuator door is buggered up. Look for missing, cracked/weathered vacuum lines under the hood, under the dash etc.
& X2 on year, make & model - very important.

 

Added year and model to original posting.....sorry....brain fart...

 

For unknown reasons, these vehicles will force air through the floor vents when the HVAC control is set to OFF. In the summer, this is pretty noticeable because you'll get hot air through the floor vents, and the flow will vary according to how fast you're driving. Once you switch the HVAC control to something besides OFF, you should only get air out of the floor vents when you're telling it to.

Not sure if this is your issue, but if it is, this is normal. If not, then you may have a vacuum issue or a broken flapper inside the dash.

 

Contrary to aa's post... off is off!
There should be no air be it from the cowl (depending on speed) or from the fan.
When the vacuum is messed up or the actuator door, they usually default to allowing air through the floor heat vents &/or the upper vents. There was a post about that in here, search it out.

 

Correct me if I'm wrong, but when the HVAC control is set to OFF, there is no vacuum applied to the recirculation door actuator. In this "un-vacuum'ed" state, the recirculation door defaults to the open position. Therefore, the outside air inlet would always be open when the HVAC **** is turned to the OFF position.

So if the inlet is open, the only way to prevent outside air from making its way to the vents would be for all of the doors and flappers inside the dash to be closed off to the vents. I could be interpreting this diagram wrong, but I don't think that's possible. It looks to me like at least one of those doors is always going to be open, whether vacuum is applied to any of the actuators or not.

As further evidence, it's pretty well-documented that when you have a vaccum problem, you only get air to come out one set of vents (usually floor and/or defrost). Which means when you set the HVAC **** to OFF and there's no vacuum anywhere, at least one set of vents is not closed off. And if the air inlet door is open, I don't see how you can prevent air from forcing its way through the vents.

 

Found-out that the hot air is coming from the two floor vents on each side of the trans tunnel. Turned temp control to full hot and air got hotter....supposed to do that. But turing to full cold and still got some hot air out of the floor vents.

Suspected that temp or blend door not fully closing. Rotated dash forward and removed temp door motor. Was able to rotate temp door with fingers....easy, nothing binding. checked position of motor gear and it was also fully closed. Reassembled, no change.

I am at a loss at this time. Do not understand why with AC on the distribution door does not shut off the floor vents. I am also able to fully rotate this by fingers....vacuum acutator is good, not leaking...holds vacuum just fine.

I also have a thud sound when going over rough road that sounds like one of the doors in the air duct is bouncing...which lead me to think I have a actuator leaking....but not able to find that either.

So like I said, I am at a loss at this time. Going to go searching for a vacuum line guide or schematic so I can trace all the lines out since I have the dash mostly apart.

Thanks

 

You could try the "hot feet fix" that has been discussed quite a bit. I experimented with this on my '04 Blazer and disconnecting the grey line did absolutely nothing. But then, I don't get hot air coming out the floor vents with the AC on. So I'm not sure why I even screwed around with it. But it's very easy to lift up on the glove box door latch bracket thing, swing the door all the way down and cap off the grey vacuum line (duct tape works pretty well).

 

Update:
Was checking vacuum hoses under the hood; pulled on hose above right fender and it came off and I got the "pssss" sound....trouble is I did not know where the end of the line connected to. I knew the canister was around there somewhere...but just could not find it.

Decided to remove the fender liner as I knew the canister was in there somewhere. After taking the liner loose discovered...nope...no access to the canister. Finally I saw the canister and more searching with fingers...found the canister nipple and put the hose back on.

Also found that at the "T" all three hoses were cracked and rotting. So I replaced all the hoses, even the one to the 4wd actuator.

What I do not understand is why are the hoses only rotten at this "T" junction? I would think that closer to engine heat would be where the hoses would fail at...odd??

Anyways I will look into this "hot feet fix" and give it a try. I know exactly where that grey vacuum line is at...thanks for the lead.

And thanks to all.