A/C Blows Warmer at Highway Speeds

[pinfante]

When idling, A/C works fine. Vent temp gets about 50 or below. At highway speeds, especially on hotter sunny days, vent temp doesn't go below 60. However, if at idle, it could be sunny and 100 degrees outside, the vent temp goes to 50 or below, and vehicle cools nicely.

Thoughts on this?

Thanks.

 

[rickybobby]

check your pressures with the engine off. they should be about 10 psi higher than ambient air temp in ferenhieght. if thats ok, check pressures running @ 1500 rpm. the low side should be between 30 and 40, and the high side should be between 200 and 250. if high side is low, it needs more charge, but that usually works better at high speeds. if high side is high and low side is low, it means there is a restriction in the system, and will usually do what you are describing. if thats the case, check all of the lines and hoses for kinks. if they are ok, you most likely need a compressor and an oriface tube