HVAC Issue: Constant air flow from panel vents.

[Ken]

I search but did not see any post related to this specific issue I am having. My HVAC system works fine, air diverts properly and blower functions ect. However when HVAC system is shut off I still get air flow through the panel vents (the blower is not running). The truck speed has a direct correlation to the amount of air coming through the vents. At 20-35 mph there is a small but noticeable amount coming through, when your get up to 70+ it feels like the blower is on low or medium low. The dealer says this is normal. I am fully aware of the fact that car makers design veh to have constant air circulation even with the HVAC system turned off. However I have never seen that residual air flow come through the panel vents at this rate or volume on any veh. The Dealer did replace the control head do to a vacuum leak. However the problem was there for a year prior to the control head failure and that is when they told me it was normal. I noticed a high pitched whistle (vac. leak) at the control head and was sure that when I took it to the dealer and had it replaced that it would fix the problem. I did not.


This issue truly makes it tough to control the temp in the truck. I have to run the a/c nearly all the time because the air coming in is hot from the eng and or heater core, it might be 60 degrees out but fells like your running the heater blowing it in your face. (I'm in Phx. area it never really gets "cold" out)

Does anyone else experience the same air flow? Maybe it is "normal" (poor design if so)?


Thanks

[F9K9]

Mine does the same thing. I have mentioned it before but, no one took much notice to my complaint. It was very obvious to me because the '97 I traded in for my crew worked excellent. I keep my dash ventss closed when I don't need AC. My '97 didn't have the cutoffs for the vents so I assume it is the nature of the beast.

[Walt]

Mine does it do, as did my 2000 Sonoma I had before my CC. Come to think of it....my F*rd R**g*r did the same thing.... Must be pretty common....

This is a family friendly site, so I "*"ed out profane words j/k

[jeff024]

mine only does it when going up mountains with the vents open if I close them im fine.
Have you done the hot feet fix?

[Ken]

Have you done the hot feet fix?

No, I read that post but thought that it really didn't address my issue. I think that a will try it and see if it at least lowers that air temp that is coming through the vents. As it does feel as if that air is coming across the heater core and or eng area and picking up a lot of heat.

I don't remember this happening when the truck was new. (I may be wrong) It seems to me that when the system is off if I could figure out a way to get the air to diver to the floor vs panel would be ideal. It would not surprise me that it is designed that way and then something fails and causes the problem. Who knows.

[jeff024]

without the hot feet fix there is always warm-hot air blowing on your feet unless you have the AC on

[Walt]

without the hot feet fix there is always warm-hot air blowing on your feet unless you have the AC on

Listen to this man! He knows what he's talking about!

hehe

During the aftermath of Hurricane Katrina, while waiting for hours in line for gas and other supplies in 90-100 degree heat, I had to shut my AC or truck off alot to keep the truck from overheating. Most of the time I turned the truck off because if I just turned the AC off and kept the truck running, that hot our coming from the floor only served to intensify the heat. I feel your pain when it comes to heat. While southern MS doesn't quite get as high as AZ in temps, we more than make up for it in humidity.

[Snoman002]

Our Bravada does this too. We can direct the air to wherever we want (floor/dash/defrost) though.

The thing I hate the most is if I turn the fan on low I can force the air to recirculate, but GM with their great ideas decided that you can only have it on recir. for so long, then it switches back to outside air and blasts you in the face. This was the worst when doing a road trip with the little one, I needed the dash vents on to push some air into the back, but every five minutes it would switch to outside air and blast air back there, then with the auto temp controll it would turn the air cooler to keep the temp the same in the truck. In the end every five to ten minutes the little one would get a face full of cold air, VERY annoying. If i turned it on floor or defrost either I would roast and the back would be fine or I would be fine and it would be cold in the back. That was a really long trip.

[kauaibuilt47]

with my CC when the tranny downshifts because i hit the gas the panel vents start shooting out air. Dont know why. did the hot feet fix though.

[HenryJ]

The fresh air system is active all the time , to the best of my knowledge. Fresh air is circulated from the cowl vent and exits the cab vent at the rear of the cab. This does a couple things. One it helps maintain a constant flow of fresh air and second it tends to maintain a positive pressure in the cabin to help seal it to outside contaminants (dust/water).

If the air is unpleasantly warm. Do the Hot feet fix. It only takes a few seconds and is a huge improvement. The system really is designed for the auto climate controls and that door should default to closed. A GM oversight.

To the issue of the loss of vacuum under acceleration. You must have a leak, or cracked vacuum reservoir.

[Ken]

Did the "Hot Feet Fix" even though my feet weren't hot; it was more of the "Hot Face Fix" in my case. None-the-less I did it and it did lower the air temp coming through the vents. I still don't like the air coming from the vents but oh well.