2018 Yukon Denali Intermittent A/C

[Footankleg]

My AC works well and blows very cold, the majority of the time. Periodically, however, it does not blow cold air for a period of time, and then all of a sudden starts blowing cold air again. It seems to be most common when the vehicle has been parked and I first get in. After driving for a little while it’ll start to kick in.

I’ve been to the dealer countless times to keep being told that a part was defective and needed to be replaced only to have the same exact problem repeat itself. I would go back, have a different part replaced and a different story. I do not believe it is a major component as it works extremely well, the majority of the time.

After my fourth or fifth return service appointment at the dealer, I was informed that they had contacted GM. The story at that point was that the engineers advised them that this vehicle will turn the compressor off for power reasons from time to time. I thought that was the biggest Lie of them all. I cannot imagine that a 6.2 L V8 would need to conserve power and turn off the AC compressor. My old Toyota Corolla with a 1.6 L engine, blew ice, cold air 100% of the time.

After the dealer couldn’t fix it, I had a private mechanic replace the control module, which was very expensive of course. No change.

Does anyone else have a similar problem or heard of something like this?

 

[Blackcar]

Do you have a list of parts that dealer replaced on the four trips?

Have you had battery checked (Load tested)?

 

[Footankleg]

Do you have a list of parts that dealer replaced on the four trips?

Have you had battery checked (Load tested)?

I will paraphrase from my invoices:

They replaced high voltage cables for possible voltage drop.

Battery replaced unrelated to AC

Recover evacuated and charge: had proper charge, tested all sensors in hvac case. ,tested hvac pressures-in spec.

Checked battery voltage/load, voltage drop cables.

Replaced condenser (seals, atf, lube, refrigerant).

F-(s) Evaporator: “leaking rear evaporator, verified low/recovered, black lamp tested and found dye at rear drain).

“no faults, checked freon level, checked for codes, checked disengage history, (low voltage and stall prevention), battery passed test.

Private shop: replaced ac control module, cabin filter, evaporator temp sensor/air duct sensors. They showed me the cabin filter after 5 or 6 service visits to dealer for above ac work. It was so dirty and full of leaves and debris-definitely years old. They also questioned whether some of the parts were ever actually replaced due to air filter condition and that all clips and screws appeared factory new condition when they disassembled dash to install module. Tech stated that they would have tool marks etc if they were in there previously.

Thank you for helping!

 

[Blackcar]

The evaporator they replaced was in rear of vehicle not the one in dash.

I know on my 2017 Yukon the with HVAC in auto will act different at times.
How long would you say it takes for AC to turn on after start up?

Does outside temperature reading on your CUE match outside temperature at all times?

 

[Footankleg]

The evaporator they replaced was in rear of vehicle not the one in dash.

I know on my 2017 Yukon the with HVAC in auto will act different at times.
How long would you say it takes for AC to turn on after start up?

Does outside temperature reading on your CUE match outside temperature at all times?

I do not use Auto, just dial the temp and adjust fan myself.

Most of the time, the ac comes on right away. My most notable issues occur from start up and then 8-10 minutes of driving before the cold air starts.

I believe that the display temp always seems pretty accurate.

 

[Blackcar]

I don't know where you live but where my vehicle is there are times temperature in morning gets to 50 degrees telling ambient sensor that's in front of radiator will hold that temp on CUE until vehicle is driven 4 miles without stopping before temp will update on CUE to temp at present which might have increased so compressor will run.

I know this for a fact when I purchased vehicle new, they replaced 3 sensors before they called GM and answer was vehicle had to be driven 4 miles and no stops for CUE to update.

My question to them was did computer read that temp on CUE or sensor before the AC compressor would kick on for air conditioning but never received answer on that situation which I think sometimes why air compressor won't run because of sensor sending wrong temp to HVAC system.

Being outside temp is at where compressor isn't supposed to run causes times when air conditioning won't work correctly for inside of vehicle. Now if I'm driving on highway, I really don't notice this problem but driving in town stop and go when morning temps are low air sometimes isn't as responsive as if should be. This is my view of HVAC on my vehicle. Which was the reason for asking if your temp on CUE was always with current temp on outside of vehicle. It might be 75 degrees outside, and CUE will say 47 degrees because I haven't driven 4 miles without stopping.