A/C PROBLEMS

[FIREWERKS]

I have a 2002 F350 4dr duelly 4x4 with 216k on it. The truck has never had a bit of major problems. All of a sudden the a/c wants to cycle on and off for no apparent reason. It some times will run for 10 miles or 100 miles before it starts acting up. When it does it just shuts down like its freezing up, you turn it off and let it set a minute and it will work again. I am an ase master truck mech. and very familiar with a/c units. But this one has me stumped. Ii've checked the low and high side pressures and they are good at idle and 2000 rpm. I've changed the low and high pressure cut out switches. I've even wired around them to see if it would change. It still does the same thing. Does any one have a clue to this mystery???

 

[powerboatr]

i dont want to insult your intellignece, i see you have gauged it and all, has the orifice tube been cleaned or replaced,??

 

[bushpilot]

I would have said it was pressure switches...or the pressure itself (only time
ive seen one STOP cyclin' or cycle more frequently...

anything in the compressor that would cause it to lock up ? clutch ?
doesnt seem to me that there is but...

 

[bartman]

I have a similar issue with mine. I have found that when I romp the throttle, it will kick back on. There are two theories as to what is causing the problem:

1) There is a piece of debris floating around my refrigerant, occasionally blocking off flow. The solution is to flush the system.

2) I have heard that TBAR had a similar issue with his, and that he found that his compressor clutch needed to be shimmed (or a shim removed) as it wasn't fully engaging.

I see both as realistic, I just haven't spent the time looking into it. Keep us posted, please.

Bart

 

[Tbar]

My a/c clutch wasn't always engaging so I took it to my mechanic. He said I was getting end play in the shaft due to wear which was causing the air gap to be too great. When the magnet came on it would not always engage.

He pulled the front plate off the clutch loose(one screw) off the front of the compresser, removed a shim and them put it back together. Mine works fine now.

Don't know if this is your problem or not but it fixed mine.


Tbar

 

[bartman]

Lance, if you come on Saturday, is this something you could look at on my truck? I wonder how to tell whether that is my problem.

 

[JLDickmon]

next time it quits, stick a screwdriver against the clutch plate and see if it's magnetized..

if it is, then I'd do like Tbar did and check the air gap...

if'n it aint, then ya'lls need to replace the clutch...

 

[bartman]

The only problem is that it does it mostly while driving which is why it never had gauges on it when it failed to see if it was spiking due to a clog. I will try to pull over and check it out next time with the screw driver.