Weird AC problem. 2010 Yukon *SOLVED*

[Sir_Hiro]

When I bought the truck it was winter. My Brother works in Hvac so we checked the Freon and it was empty. We filled it and the air worked wonderful for a while.
Now that its been hitting 70-80Fs here its stopped working. Compressor isnt short cycling and according to my Cheapo Gauge the pressures are within spec. I did hit the valve on the high side and it had freon.
What else is there to check?

TLDR: Compressor is running but no cold air, Pressures good

 

[Doubeleive]

When I bought the truck it was winter. My Brother works in Hvac so we checked the Freon and it was empty. We filled it and the air worked wonderful for a while.
Now that its been hitting 70-80Fs here its stopped working. Compressor isnt short cycling and according to my Cheapo Gauge the pressures are within spec. I did hit the valve on the high side and it had freon.
What else is there to check?

TLDR: Compressor is running but no cold air, Pressures good

are the hvac lines under the hood cold after it has been running for a bit? if so then the issue is likely a blend door actuator.

 

[Sir_Hiro]

are the hvac lines under the hood cold after it has been running for a bit? if so then the issue is likely a blend door actuator.

Ice cold. I do have the Auto Climate control I should have mentioned. But if I go to max hot..It'll melt your face off.

 

[Doubeleive]

Ice cold. I do have the Auto Climate control I should have mentioned. But if I go to max hot..It'll melt your face off.

the hot/cold blend door is the one under the glove box, you have to pull the kickpanel under the glove box (3) 7mm, you can remove the 2 farthest ones and then just push it down out of the way the 3rd one is hard to get to. then the actuator is bottom dead center uses (2 or 3) 5.5mm bolts, when you adjust hot/cold you should see that actuator rotate, if it's not moving that would explain why you have heat only. if you pull the actuator you can move the door manually and then see if you have cold air.

 

[rdezs]

Also if you have the rear AC, see if it's blowing cold while the front is warm. That will verify it's the blend doors up front.... Or the signals they are receiving from the HVAC module. (Which often is traced to a bad cabin temperature sensor)

I miss the vehicles with cable operated controls. Was so much more reliable.

 

[Sir_Hiro]

Update* front ac lines are ice cold however rear ac lines are ambient temps. Im starting to suspect that its just low on charge and my cheapo low pressure guages isnt right.

 

[Sir_Hiro]

the hot/cold blend door is the one under the glove box, you have to pull the kickpanel under the glove box (3) 7mm, you can remove the 2 farthest ones and then just push it down out of the way the 3rd one is hard to get to. then the actuator is bottom dead center uses (2 or 3) 5.5mm bolts, when you adjust hot/cold you should see that actuator rotate, if it's not moving that would explain why you have heat only. if you pull the actuator you can move the door manually and then see if you have cold air.

I will try that later. Working on the C10 till its cooler out

 

[Doubeleive]

Update* front ac lines are ice cold however rear ac lines are ambient temps. Im starting to suspect that its just low on charge and my cheapo low pressure guages isnt right.

the rear lines won't be very cool no matter what, not externally anyway that is normal, the lines are just too far away from the compressor to be cold to the touch
maybe.... after it has been running for a good while they might feel slightly cool, they may even sweat condensation, but not like the lines up front.

 

[Sir_Hiro]

the rear lines won't be very cool no matter what, not externally anyway that is normal, the lines are just too far away from the compressor to be cold to the touch
maybe.... after it has been running for a good while they might feel slightly cool, they may even sweat condensation, but not like the lines up front.

Interesting. I've never really messed with HVAC systems. If it wasnt for the Little one I wouldnt bother fixing it. But we need the AC for the long family roadtrips. I'll verify the Actuators today.

 

[Sir_Hiro]

Ordered some proper 3 Way AC Gauges, Should arrive today. Will be able to hopefully verify pressures and go from there. Compressor started short cycling yesterday when I was running it.