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.
AC Blows Hot not the belt
- Thread starter 03_GMC
- Start date
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swathdiver
Full Access Member
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
Full Access Member
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.
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.
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
Full Access Member
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.
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.
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swathdiver
Full Access Member
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.
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)
Alternate Method (w/o Scan Tool)
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.
- Place the ignition switch to the OFF position.
- Disconnect the scan tool.
- Install the HVAC control module.
- Connect all previously disconnected components.
- Start the vehicle.
- Wait 40 seconds for the HVAC control module to self-calibrate.
- 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.
Preferred Method (w/Scan Tool)
- Clear all DTCs.
- Place the ignition switch in the OFF position.
- Install the HVAC actuator.
- Connect all previously disconnected components.
- Start the vehicle.
- With the scan tool, initiate the Motor Re-calibration feature of the Heating and Air Conditioning Special Functions menu.
- Verify that no DTCs have set as current DTCs.
Alternate Method (w/o Scan Tool)
- Clear all DTCs.
- Place the ignition switch to the OFF position.
- Install the HVAC actuator.
- Connect all previously disconnected components.
- Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
- Install the HVAC/ECAS fuse.
- Start the vehicle.
- Wait 40 seconds for the HVAC control module to self-calibrate.
- Verify that no DTCs have set as current DTCs.
swathdiver
Full Access Member
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
Full Access Member
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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.
kbuskill
***CAUTION*** I do my own stunts!
Can you see the different sensors and what not for the HVAC show up on the Tech 2?
I would also check the interior air temperature aspirators to see if they are clean.
When I recently replaced mine the grills were full of dust/lint.
There are two in the headliner...
One above the drivers seat, looks like a speaker grill about 1" in diameter.
The other is in the rear between the 2nd and 3rd row on drivers side... looks the same.
Perhaps just pull the grills and make sure they are clean and clear.
Yes I can see the temperature of all the inlets and outlets and such. I’ll check the screens for those and see.
swathdiver
Full Access Member
Did you check the commanded and actual state of the doors? Did you check the line pressures and such too? There's so much the Tech2 can do with regards to the HVAC system.
Honestly I looked at so much stuff I’m not sure. I spent a lot of time in the HVAC system and I’m sure I saw them but don’t remember what they read. What should I expect to see for those things? Thanks.
swathdiver
Full Access Member
The doors should be within a few counts of commanded and actual. But then you can also see the temperatures, commanded and actual as well. I'm a novice too, but I think it's worth another look at the system with the Tech2. There's another guy here who this AC stuff really well, pressures and all. Let's see if he chimes in. @Doubeleive too!
I don't know about the pressures, that would probably be @sumo but I can say if the accumalator is getting cold and sweating then at least you know that part is working or not and then proceed from there.
Definitely sweating going on. Like I said it apparently just randomly happens. It has yet to do it to me but has done it multiple times over the past year for my wife. I’ll check the commanded and actual sod everything and see if stuff is close or way off.
I'd say if it's def getting cold and the doors and actuators are working then the control is probably gone goofy
