AC Blows Hot not the belt

[03_GMC]

so I’ve been googling and searching. Maybe my phone isn’t getting me to the right place but either way. My wife’s 09 Denali XL blows hot air sometimes. Not all the time just sometimes. She said if she shuts off the hvac controls on the dash and then turns it back on most of the time it starts working again. Any clue what it is? Thanks.

 

[swathdiver]

It is probably a door malfunctioning or out of synch or could be low on freon. Do you have access to an advanced scan tool like a Tech2 Brandon? Where do you live, maybe someone on here lives close by with something that can see what's going on inside?

 

[03_GMC]

It is probably a door malfunctioning or out of synch or could be low on freon. Do you have access to an advanced scan tool like a Tech2 Brandon? Where do you live, maybe someone on here lives close by with something that can see what's going on inside?

Thanks for the reply! A coworker has a tech 2 device so I think I will take him up on it. I’m in the Dallas area.

 

[swathdiver]

Thanks for the reply! A coworker has a tech 2 device so I think I will take him up on it. I’m in the Dallas area.

Excellent! With it, he can see the commanded and actual state of the actuators and should one be out of synch, push it back into position with the Tech2 as long as it is still working. He can obviously pull up the codes and do a complete reset of all the actuators. On the AC side, he can see the state of the compressor and the pressure readings and such and run tests on that too.

If you plan to keep the Denali for a time, consider getting your own. If you want something that can diagnose both the Yukon and Cruze, get the MDI with GDS2 software and a laptop.

 

[Doubeleive]

my guess would be low Freon or a bad a/c controller (the one in the dash), that is a symptom of either. in my experience anyway.

 

[03_GMC]

Apparently this happened last year as well and she never said anything to me about it lol so I’m guessing it’s not a Freon issue. But I may give it a little recharge anyway. Hopefully he has the right kind of tech 2 tool. From what I’ve seen they are like $2K? Unless you get one off amazon? I’d love to be able to do my own regens on my Cruze when it screws up until I get it deleted.

 

[Scottydoggs]

give this a shot, system reset.

edit, wrong year. but there might be a re set like this still. even my 98 regal, if i pull the cluster fuse it kills the climate control. and resets the actuators. what i do when it starts blowing warm on one side. fixes it every time.

 

[swathdiver]

For GMT900 with Auto HVAC:

Actuator Recalibration

When replacing the HVAC control module it will be necessary to allow the HVAC control module to perform a calibration process. When installing the HVAC control module be sure to perform the following:

Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

1. Place the ignition switch to the OFF position.
2. Disconnect the scan tool.
3. Install the HVAC control module.
4. Connect all previously disconnected components.
5. Start the vehicle.
6. Wait 40 seconds for the HVAC control module to self-calibrate.
7. Verify that no DTCs have set as current DTCs.

When replacing the HVAC actuator it will be necessary to allow the HVAC control module to perform a calibration process. When installing the HVAC actuator be sure to perform one of the following:

Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Preferred Method (w/Scan Tool)

1. Clear all DTCs.
2. Place the ignition switch in the OFF position.
3. Install the HVAC actuator.
4. Connect all previously disconnected components.
5. Start the vehicle.
6. With the scan tool, initiate the Motor Re-calibration feature of the Heating and Air Conditioning Special Functions menu.
7. Verify that no DTCs have set as current DTCs.

Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.

Alternate Method (w/o Scan Tool)

1. Clear all DTCs.
2. Place the ignition switch to the OFF position.
3. Install the HVAC actuator.
4. Connect all previously disconnected components.
5. Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
6. Install the HVAC/ECAS fuse.
7. Start the vehicle.
8. Wait 40 seconds for the HVAC control module to self-calibrate.
9. Verify that no DTCs have set as current DTCs.

 

[swathdiver]

Apparently this happened last year as well and she never said anything to me about it lol so I’m guessing it’s not a Freon issue. But I may give it a little recharge anyway. Hopefully he has the right kind of tech 2 tool. From what I’ve seen they are like $2K? Unless you get one off amazon? I’d love to be able to do my own regens on my Cruze when it screws up until I get it deleted.

You can get a Tech2 for less than $400 these days. The MDI are about $275 but so is the GDS2 software and you'll need a laptop for the Cruz. While its a chunk of change to lay out, they will certainly pay for themselves in short order.

 

[nadthomas]

I recently ran into this issue, and initially thought the system just wasn't blowing cold air at times. After looking into it further, and having a passenger in the car I was able to confirm I was just getting hot air out of the driver side vent, but passenger side was nice and cold. It was the blend door actuator that was going bad. Its basically just a small motor that turns a flap in the HVAC ducts to route hot vs cold air. Replacement was simple, but in kind of a tight place under the dash, and all is good now.