2005 F250 6.0
A/c gets nice and cold while at low speeds (20 mph) and under or stopped at a red light or coasting from letting off the throttle.
A/C will be at a nice 53/55 degrees but will jump up to about 67 degrees once accelerating or at higher speeds. I don't believe my compressor is shutting off because its still staying cool just not cold, If i turn it off manually it will jump to the high 80's.
At Idle low side sitting at about 40ish high side is about 225-250ish.. outside temp 112, ambient temp under the hood roughly 130.
I checked my clearance on my clutch sitting at about .025.
Now I hooked my gauges up while driving and my high side will build to about 225 then fall to 100, will build to 250 then fall to 100, it will do this repeatedly until I'm at low speeds in the neighborhoods. My low side connector just so happen to break while doing this test so I only have high side readings while driving, waiting to replace the fitting.
Compressor and orfice tube(which was severely clogged) both replaced at the end summer last year. Did great for the few weeks i used it till fall.
Faulty compressor clutch already?? Slipping at higher rpms? But I do not hear any grinding noises.
Orfice clogged already?
Faulty electrical connection at the compressor? I did wiggly the connection while it was running, didn't effect anything.

 

Fan Clutch?

 

Fan clutch... what...is slipping? Cutting out under stress(rpms)? Is being turned off from high pressure switch?

 

You need to also see the low pressure side of the system. Fix that first so you have proper data to analyze.

Your high pressure readings suggest that the compressor clutch is cycling but, without the low pressure readings, it's not possible to be certain that the cycling is due to the cycling switch or to some other input to the PCM. You may also need to hook up an appropriate scan tool and monitor the low pressure input to the PCM and the AC Relay output command status to determine what's going on since this is a PCM-controlled system.

By the way, when the compressor was replaced, was the system charged properly by exact weight to specifications or was it a guesswork job with 12 ounce cans?

 

Ok low side gauge was fixed. When I am driving, cruising at higher speeds not neighborhood speeds, when the high side builds and suddenly drops off, builds and drops off( non stop till i slow down or stop)....the low side jumps from 35-40 to 60ish. Just vise versa form the high side, which makes sense to me. High and low side are trying to balance, correct? I replaced the compressor a year ago along with the orifice tube. Vacuumed the system and let it sit...no leaks. But yes filled it using 12oz cans.

 

Sounds like it's cycling via the low pressure switch although your low side gauge is reading 10-15 psi higher than expected. Typical low side switches on most Fords should open around 22-25 psi descending and close back up around 45 psi ascending.

Sounds to me like it's undercharged and is short-cycling once the compressor is turning faster.

Test system at 1500 RPMs, not at idle speed, when stationary. Doors open, system on Normal A/C, blower on highest setting, temp **** all the way to the cold side.