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F250 intermittent compressor cut out

Drake57 on Tue June 17, 2008 10:28 AM User is offline

Year: 2000
Make: Ford
Model: F250 Diesel
Engine Size: 7.3
Refrigerant Type: F134a
Ambient Temp: 100
Pressure Low: 40
Pressure High: 250

AC is cold, but occasionally compressor cuts out, and vent air warms up. Turn AC off or vehicle engine off for a few minutes, or just wait five minutes then it works again. Problem is intermittent, did not duplicate with gauges on the system.
1) Does anyone have basic information about control system such as would help troubleshoot? I see a pressure switch on both the high and and low pressure coolant lines.
2) Do diesel vehicles such as this one have an auxiliary vacuum source, and can anyone say if loss of vacuum could cause intermittent loss of cooling?
Thanks for any help, Drake.

GM Tech on Tue June 17, 2008 10:47 AM User is offline

Next time you catch it not cooling- pop the hood- look at compressor if clutch is not turning- VERY carefully tap on it with something solid- like a wooden hammer handle- and see it if engages and takes off running-- if so - then your air gap is too wide (from wear) and it needs to be closed up some- this is done by removing the clutch driver and removing an appropriate spacing shim to yield an air gap of approx .020" then all will be lovely--

If above test does not work-or clutch IS turning- then you may have other electrical problems- or perhaps even freeze-up- look for frost on any low side lines...

The number one A/C diagnostic tool there is- is to know how much refrigerant is in the system- this can only be done by recovering and weighing the refrigerant!!
Just a thought.... 65% of A/C failures in my 3200 car diagnostic database (GM vehicles) are due to loss of refrigerant due to a leak......

Drake57 on Tue June 17, 2008 10:53 AM User is offline

Oops I guess I forgot to mention, that the owner checked compressor during a cut out occurrence, and reports that compressor is not engaged during cut out, and after a time compressor re engages, and vent air is cool again.
Thanks, Drake.

bohica2xo on Tue June 17, 2008 1:16 PM User is offline

Check the clutch gap, or as GM Tech suggested, tap on the face of the clutch to see if it will engage.


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~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Dougflas on Tue June 17, 2008 1:34 PM User is offline

Fords had defective low pressure cycling switches. Just change it; if it's not the problem now, it will be later on.

Drake57 on Tue June 17, 2008 4:46 PM User is offline

Thanks for all the assistance. I hope this doesn't sound dumb, but can the low pressure switch be changed without discharging the system?

Thanks again.

Chick on Tue June 17, 2008 6:32 PM User is offlineView users profile

Yes the cycling switch can be changed without discharging the system, but my best guess is the clutch gap also..I'd check that first... Hope this helps.

Email: Chick


Freedoms just another word for nothing left to lose

Drake57 on Mon July 07, 2008 10:31 AM User is offline

Thanks guys, it was the gap. The clutch surfaces had worn, the gap was about 0.035. Engagement by nudging the hub with a hammer handle was a very strong indicator. Changing the shim acheives constant cooling.

Again, thanks, Drake.

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