Air Conditioning won't work above 2,000 RPM?

BARTLETT_LAW

MEMBER
2006 FORD F-350
V8
4WD
AUTOMATIC
75,000 MILES

I have a 2006 Ford F350 that Ii haul a 4 horse living quarters trailer with (about 14,000 lbs). The Air Conditioner cools fine when you first start the vehicle and for about the first 30 minutes of operation. However, after that, if you operate at above 2,000 RPM under load, it will start blowing warm air and will not start to cool again until you have either come to a stop or operated that fan for 10 minutes (after which it will typically only work for about 10 more minutes). I had the dealership check the refrigerant pressure and they say everything is fine. Because they couldn't drive around with my trailer for an hour, they also could not replicate the problem. Any ideas?

2 Replies

2CARPRO JACK

MECHANIC
11,533 POSTS

The only reason I could think that the trailer would matter if it is creating more heat in the radiator that is causing the pressures to increase to the point where the system is either shutting down or it just has too high of pressure to work properly. Would have to know the high and low side pressures while engine is hot to make any other guesses as to what it could be. Next time when it isnt getting cold, try letting thetruck idle adn running water over /through th ea/c condensor (in front of radiator) to see if it starts blowing cold, also verify the compressor is engaged when it isnt working