[ewbeye]

2000 F350 7.3L 6spd 4x2 crewcab, 263,000 miles. The AC has always worked great up until now. Local mechanic tried to add some freon, but it took little or none. After he added it, it blew cold for maybe 2-3 miles, then none. Took it back to mechanic today & he had ordered a good used selector switch cluster (blower, thermostat, & selector control) thinking the selector control had gone bad. Mechanic was busy, so my son & I swapped the good used switch cluster in and it did not help. Here are few quirks that we did noticed:
1. Blower is fine - low, mid, & high speeds work good. However it only blows in the defrost vented position. Whats with that? All other vent selection do nothing but blow in the defrost vents.
2. Thermostat seems to be working? It gets hotter when turning in the hot direction.
3. Checked all fuses on the drivers side panel in the engine compartment. All fuses were good, none blown.
4. The AC compressor is not engaging when the cab selector switch is set on AC, AC Max, or Defrost.

Any help is appreciated! It is too hot & humid in Illinois now for no AC!!!!

 

[ewbeye]

After I posted my thread, I read earlier posts about this subject. Many others have had same problems. So, I went to work fixing it. Found my electric vacuum pump was unplugged. Plugged it in and that took care of the defrost vent only thing. Next, I pulled the compressor electric clutch shim out since it was over 0.050 clearance. This put the clearance around 0.025, so it was good to go. The compressor clutch still did not engage, so I started moving some wiring around near the cold tubing electrical switch?? located on the outlet side of the compressor. The wires had some sort of a short circuit in them. I found that taping them closely to the switch connected the circuit. Low and behold, the compressor came on and is working normal. AC is now blowing cold again and everything is functional. Thanks everyone for earlier posted information!! It was extremely helpful. I am looking forward to a cooler day tomorrow in my truck.