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GMC Savana air conditioning drops off while idling

We have a sled dog team and purchased a 2012 GMC Savana, pulled out the seats then added wire dog kennels to transport them. This question involves air-conditioning since we don’t want hotdogs. Traveling on the highway during the summer in 90 degree plus weather the air conditioning works fine and cools to 35 degrees plus or minus out the vents (We have a thermometer on a vent). When we stop at a rest stop to potty the dogs we leave the engine running and the air conditioning on to keep them cool. Almost immediately the air blowing from the vents starts rising to 70 degrees. My 2012 Ford Explorer does not have this issue and holds a steady cool temperature while at idle. Our dealer added dye found a leak and it was repaired so the system is topped off and the problem has persisted. Any ideas where to look next such as failed switches or compressor problems and what a dealer needs to do to make a repair. They feel the air conditioning is preforming well.

If the A/C works fine rolling down the road but gets warm idling, I would suspect a bad fan clutch. When you get back to when the air is warm, duplicate the complaint then put a fan in front blowing through the radiator and condenser. If the A/C gets cold when doing this, then I would suspect the fan clutch.

Our car would heat up at stop lights, it turned out for me that the blower motor resistor was blown, and the fan was not actually running on speeds 1 and 2, try it at a higher fan speed you can be sure i working by the sound.

+1 for @“pete peters” Sounds like a bad fan clutch.

Can’t be the fan clutch.

Because if it were, not only would the AC stop working, but the engine would also start to overheat.

Is that happening?


Yes, that’s true. But if the clutch is in partial failure mode whereby the fan is turning slower the air flow might be enough to keep the engine from overheating but not enough to cool the condenser efficiently. Just a thought.

I’d want to to know what the system pressures are. While it’s not often done, my opinion is that certain things like this should be notated on the repair order for the customer. This could greatly help if questions arise later.

Point being that at low RPMs the pressures change as compared to elevated RPMs and the compressor could be short cycling on and off.

Did the dealer tell you where this leak was at? That should also be notated on your copy of the repair order.
The point on this is that sometimes if someone does not know they may manufacture something so that it appears “they tried”. Trust me on this; it happens. A lot.

Thanks for the comment’s. I will stop by the dealer and see if their records note any pressures and where the leak was. The information is not on my customer copy. I also did not observe if the engine temperature also began to rise when idling but I will watch for it.