Ac Intermittently Blowing Hot Air

lesZ71 · August 11, 2011

I have a 2004 Z71 with dual climate control. Recently when running the AC, it will randomly begin blowing hot air instead of cold. No matter what I try, the only proven way to get cold air to blow again is to shut the engine off, wait around 5 seconds, then crank back up. After doing this everything seems to work fine for a week or so...then the AC starts blowing hot air again. Any ideas as to what the cause of this would be? Any feedback would be greatly appreciated...it sucks having your AC go out when it is already around 100 degrees outside!

drknow90rs · August 11, 2011

I would check the charge in the system. You might be just a little low on refrigerant. (Low enough to intermittantly trip the "Low-pressure" switch.)

If it's not the charge, then I would move on to the low pressure switch itself.

Next check the wiring to the clutch at the compressor.

HTH!

alvocado · August 12, 2011

It's unlikely to be refrigerant since you get cold air. I would suspect the compressor clutch or a relay module (my money is on the latter.)

Chris · August 12, 2011

may be blend door actuators

lesZ71 · August 12, 2011

Noticed this afternoon that the passenger side kept blowing cold air when this occurred. The vents on the driver side and rear were blowing hot air. When this happened previously all vents were blowing hot air.

fighter42487 · August 13, 2011

had this same problem with my 2004 sierra, dealer says its the cycling switch located on accumulator.

wvurhino · August 14, 2011

Does it happen on just the driver side? Thats my problem. Passenger side is fine, driver side is broken. I am considering converting my truck into a right hand drive. The permanent solution isn't very hard or expensive. http://chevroletforum.com/forum/silverado-...lacement-22624/ The temporary fix is to turn the truck off and back on. That usually fixes mine for a few days.

I pulled my actuator out the other day to see for myself. The hardest part was the last screw holding up the plastic cover above the center hump. Gonna kick that engineer.

The part is $137 on gmpartsdirect. Thanks to their wonderful website, there is no direct link or part number. When added to cart it shows as "Air conditioner and heater, Evaporator and heater components, Actuator, Mode temp and def, Mode temp and def - 2003-07 - 2003-07" Somewhere along that path, you will see a View Illustration button. Its item 21 which matches shape and location of the other forum instructions.

I'm still on the getting a new truck fence so I don't want to put more money into this one while I decide.

lesZ71 · August 19, 2011

Yes, it only happens on the driver's side and rear vents (ext. cab). Also has the digital climate control...not sure if that would make a difference. Passenger side remains nice and cool.

Based on the information the link you provided, I am starting to think it most likely is an actuator. I have also been having some thoughts on trading for a newer model, even before this issue.

txab · August 20, 2011

Actuator

lesZ71 · March 27, 2012

Ok...I have been putting up with this issue long enough. I managed to get through cooler weather without it being a problem. Now it is warming up and the problem appears to be worse. I have read enough about this issue and feel like it is most likely a blend door actuator. The only thing I am still a little fuzzy on is if it is the one located on the passenger side floorboard. I think it is but just want to make sure. Can someone verify this for me. Thanks!

SouthCo · March 27, 2012

Yep like a few other said. It's your blend door actuator. My wifes 05 has done it a handful of times and only on the driver's side too. I'm not fixing it until it does it on a regular basis. Shutting the truck off and restarting it fixes it every time. So since I havent addressed hers I dont know if its the one you mentioned.

lesZ71 · March 27, 2012

Think I might purchase a code scanner to see if any codes have been thrown. Be good to have one anyway. Hopefully it is the one on the passenger side floorboard.

lesZ71 · March 30, 2012

Got a chance to remove drivers side actuator and verify that was the problem. Dropped 150 bucks for a new one at Advance Auto Parts and installed it earlier today. So far everything seems to be back to normal. After taking the old one apart it is really hard to understand why it costs so much.

MVP.in.AZ · September 9, 2013

I searched and found this thread, and it helped me clear up the issue on my 2004 Silverado 1500. It was the air blend actuator, and I fixed it with no cost, just some time and elbow grease.

http://www.gm-trucks.com/forums/topic/67578-ac-goes-to-heater-mode-by-itself/

Good luck!

Bbraden1984 · March 22, 2017

I have a 2008 silverado 1500 and the ac only blows hot air out of both sides, was working fine last summer. Only thing I have done was disconnect the battery to clean terminals, but replaced properly. Any ideas? Ohh and I checked the actuator gear to see if it moves when I change the temp from hot to cold and there is no movement.