AC cuts off in hot weather

chevrolet
tahoe
airconditioning

#1

Vehicle is the newer 2000 Tahoe bodystyle. If temps are above 80 degrees and if I am not traveling very fast or am parked, the ac will cut out. Fan will still blow warm air.



However, usually once I get up to highway speeds, 50+ mph, that ac will kick back on within 1-2 minutes. Problem is intermittent and does not always occur.



Took it to a dealer and would not duplicate problem, and dealer could not find anything wrong. According to dealer, system is fully charged. Got an answer?


#2

I suggest your having an electrical problem with the A/C control circuits. Some troubleshooting with a multimeter and a wiring diagram for this truck is required. The trick is to find out why the A/C controller is not sending 12V to the mag clutch on the compressor.


#3

It kind of sounds like what happens when the electric radiator fan goes out, except that this truck doesn’t have one! It might be worth checking the fan clutch. Have you noticed the coolant temperature running high lately?


#4

Your Tahoe has a compressor outlet high pressure cutout switch. If there is not enough air flowing through the condensor or for another reason the condensor cannot get rid of the heat, the cutout will disengage the compressor clutch. In the shop a floor fan is usually placed in front of the vehicle during testing so lack of air flow may not be noticed. You might visually inspect the compressor clutch when this lack of cooling is happening. If the face of the clutch pulley is not turning, the compressor is not engaged. As GreasyJack posted check to make sure the fan clutch is engaging. It is quite possible that the clutch has leaked its fluid or otherwise failed.

Something else that can cause high output pressure is air in the system. Even though the refrigerant will condense at the correct temperature, air will collect in the same space causing the total pressure to be higher than temperature would indicate. However, this would show up on the gauge set the mechanic attached to the system.

Hope this helps.


#5

coolent temp has been fine


#6

I have been trying to pay close attention to how the problem manifests. I noticed that the a/c will come back on at constant speed of as low as 25 mph. Also, this morning, it was a little cool out, so i went to put the heat on and got no heat unless i put the temp to the highest setting (it was in the mid 60’s outside). i tried this several times on my way to work to make sure that it wasn’t just that the engine had not had time warm up and it did it every time. I now am wondering if i have a problem with the climate control?? or maybe more than one issue going on.