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Ron, ASE Certified Technician
Category: Buick
Satisfied Customers: 36039
Experience:  34 years as a Tech
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2011 Buick Enclave. AC cuts in and out. been back to dealer

Customer Question

2011 Buick Enclave. AC cuts in and out. been back to dealer twice. Actuator replaced but the compressor cuts in an out and seems to do it more when hotter. Turning it off for a few minutes then back on sometimes fixes it but maybe 2 out of 4 times. Compressor gases are correct and when last in the shop it ran in the garage just fine. We have tried alll the settings to see if one may solve the issue. When it fails you can't turn AUTO off. We had the temp set to 60 degrees and still it cuts in an out. Often it turns off (by this I mean the compressor light goes out or turns off and on before temp is reached.) With other issues deemed ok then does this mean a bad ATC processor maybe? IF this is a common issue then the techs at CARMAX aren't aware of it. MIne was a GM mechanic for 15 years.
Submitted: 1 year ago.
Category: Buick
Expert:  Ron replied 1 year ago.

Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

When the AC fails the system should detect it and set and store a fault code and or codes. Can you scan the system and see what the B code is that should be setting? Post back with the results and I will see if I can help you get this resolved.

Customer: replied 1 year ago.
following up on your answer to my Buick Enclave AC question. Its a 2011. No B codes identified by the mechanic, however I have been making observations to see if I could find the smoking gun or at least narrow things down a bit. Obviously the term intermittant is still operastive, however, it seems the ATC seems to be more troublesome as the temperature raises, with 90 being a rough threshold. Saturday it was 99 on the interstate an nothing we tried woulf get the compressor to come on an stay on. We jumped off the highway and took some back roads home and the temp dropped to below 99 and after several shutdowns and re-starts after 2-5 minutes it started cooling. Now to me it sounds like a pressure issue either in the system or the car. The car didn't overheat but I read there is a cutout to shut down the AC in that event. Also if the AC pressures are too low (low refrigerant) or too high (overcharge,blockage????) So this is a bit narrowser than before for I see it malfunction more when the temp rises outside and restarting the AC doesn't resolve the issue.
Account # ***** and Order ID# *****
Customer: replied 1 year ago.
Just belt and suspenders here since I wasn't sure my response got through. The Chat wasn't responding.
Expert:  Ron replied 1 year ago.

Well with no fault codes to go on I think I would start with checking the power in and out of the AC compressor clutch relay . I have enclosed the wiring diagram in the link below to do this. Copy and paste the link to your browser to open and view it.

Expert:  Ron replied 1 year ago.

Check this when the system fails and let me know what you find.

Customer: replied 1 year ago.
kind of a catch 22 here because I am not repairing the problem myself. Instead I am researching other smoking guns for the dealer tech who could not observe the problem with the car in the shop and on a test drive. Now unless the system (OBD) catches a fault, in this case a B code, and stores it in the computers memory there is no way anyone can define an issue, right? So I have been researching some probable causes including manufacturers defect to get to a possible solution including replacing some major component inside which a fault exist that otherwise is undectable with OBD diognostics. The car has a warranty on it and I have a deductable which I have paid to CARMAX to fix this issue. If I got to a separate dealer then I will have to pay another deductable without any assurance I will get the issue resolved. So the thing I have observed for sure is the hotter the outside temp the more the compressors fails to operate. Now since it was doing that before I took it in (twice) it would have a code set that he should have seen. right? Therefore there is some problem outside the OBD capabilities that is at play. Now this is a long shot I know but is it possible to overcharge an AC system and it not show up until hight temp place a load that causes the ac system to trigger high pressures and stop the compressor? When it is cooler out the system work fine. I understand that car ac's are not critically charged and have a receiver dryer on them so the charge is cariable somewhat and still function. Any chance that evacuating the system and then recharging would resolve high temp failures?
Expert:  Ron replied 1 year ago.

If the fault is an electronic control issue there there should be a fault code and yes it is possible to over charge the system and it can affect it once the system is operating and can cause the compressor to kick off if the pressure is excessive. I would also be something like the clutch field coil getting hot in warmer weather and causing it to kick out. Is there any chance you can get me your pressure reading with the system running?

Customer: replied 1 year ago.
They were normal according to the mechanic when I had it there last. But then the garage has AC and would not reflect pressures under a hot car load. I thought he said they were 35 L and 220/30 high. That was with the system running in a garage after about 30 minutes with the temp on theATC set for 60.
Expert:  Ron replied 1 year ago.

Normal pressure on a full system should be right at 35 to 40 PSI on the low side and right at 200 to 225 PSI on the high side.

Customer: replied 1 year ago.
Fyi nothing has changed. I sent your comments to Carmax service and as yet no al, ternate plan formulated.
Expert:  Ron replied 1 year ago.

Okay , Im here if you need me.