Automotive Air Conditioning Information Forum

Hello all, new to the site and need some help. Have a 04 Ford F250 5.4l that the ac blows cold then hot. Over the winter I removed the condenser while doing some work. I put it back together with a new drier and orifice tube in the system and put in 42oz of 134A. It was nice and cold then drove it the next day and it started off cold then went hot. Came home looked for leak as I have dye in it. It looked like the high side valve might have a slow leak. Replaced it clean any dye up evacuated it again and recharged it. Still the same issue. No leaks found and my pressures are good. When the truck turns off and then go and use it again it start off cold again. It does sometime get warm and then back to cold. When it gets warm I novice the clutch disengaged so I replaced the pressure switch on the drier which I believe is the low pressure. I can not fing a high pressure switch to replace What might the issue be??? Any help would be greatly apricated. system pressure when running low 46psi / high 225psi @ 92 degrees.

woody367 wrote: ↑Sat Jul 13, 2024 5:27 pm When it gets warm I novice the clutch disengaged...

When the AC clutch is disengaged, CAREFULLY tap on the AC clutch drive plate (the center section) with a wooden broom handle or similar. See if that engages it, which might show a too-large clutch gap. I removed an AC clutch shim back in 2019 on my 1998 Frontier to fix a too-large air gap, still working.

If your AC clutch is still getting positive voltage when disengaged and not an air gap issue, then maybe the AC clutch coil is bad.

All this assumes that you have the correct amount of ounces of refrigerant in the system.

Do you mean it blows hot as in heated air, or air at ambient temperature?

Sure sounds like too wide a clutch gap from here. This is adjustable. Should be .020

I checked my air gap and .035 was just a little snug. I guess I should try taking a shim out? If that is the issue why would the clutch engage and produce cold air but after like 15-20 minutes the clutch disengage?

woody367 wrote: ↑Sun Jul 14, 2024 12:55 pm I checked my air gap and .035 was just a little snug. I guess I should try taking a shim out?

YES

woody367 wrote: ↑Sun Jul 14, 2024 12:55 pm If that is the issue why would the clutch engage and produce cold air but after like 15-20 minutes the clutch disengage?

Because it heats up ! That's what my 1998 Frontier did.

woody367 wrote: ↑Sun Jul 14, 2024 12:55 pm I checked my air gap and .035 was just a little snug. I guess I should try taking a shim out? If that is the issue why would the clutch engage and produce cold air but after like 15-20 minutes the clutch disengage?

Remove one shim (maybe the only shim) and then verify the air gap. As tbirdtbird said, it should be ~0.020", but double-check the specs for your truck.

The reason that the compressor disengages and cooling stops after 15-20 minutes has to do with clutch-cycling and limited magnetic force—and to a certain extent, heat, as Cusser mentioned. When the clutch cycles off during that time, the electromagnet inside the clutch doesn't have enough force to overcome the air gap, engage the clutch again, and drive the compressor.

Took the clutch apart, and only found one spacer. I removed it. Put it back together and now I have a air gap of .026. Not down to spec of .020 but I guess it's better then nothing we'll see what happens. Thank yoiu for the help.

Two ways to reduce the clearance when there are no more shims to remove:

—Grind off the end of the tube (the end that bears against the shim) using a bench-top disk sander or an appropriate Dremel tool. Use care to ensure the end of the tube remains square, and take off only a little at a time, rechecking the clearance after each grinding.

—Replace the compressor/clutch assembly with a new one. Usually, the entire assembly can be replaced at less cost than only the clutch.

I may try the idea of grinding the end of the tube.
As far as replacing the whole unit, I can't seem to find one made by Ford Motocraft Anymore for that truck.
Is there a good quality brand replacement compressor for the Ford?