I have a 1997 F150, 4.2 liter. Two weeks ago the AC stopped working. The only thing I have noticed is the AC clutch will only engage for a couple of seconds then disengage for a couple, reengage for a couple and so on. I have checked the pressure and it is fine. No apprent leaks in the system. I have jumped the low pressure switch and the same thing happens. I have removed the blend door actuator and made sure the door is open for AC which it is. One of the tubes coming off dryer is very cold and drips condensation. Any ideas?

Is the clutch supposed to stay engaged the entire time the AC is on?

 

It sounds like you are low on Freon.
You say you checked the pressure and it's fine.....did you use a refrigeration guage set or one of those quick tester you get at the parts store?
Proper diagnosis REQUIRES looking at both high & low side pressures with the system in operation.

Refrigeration systems are complicated and dangerous to work on without the proper tools and knowledge.

The AC clutch can cycle on and off under some conditions in a properly functioning system. Based on your description, I guess that it's low on freon. The system should not lose any freon unless there is a leak somewhere. These systems have rubber hoses, fittings with O-rings, many places that can and usually will leak eventually.

Bottom line, if you don't have the proper tools and knowledge, don't mess with it. Take it to someone who knows what they are doing.

 

Been a long time for me with AC related items. Are you sure you jumpered the cycling switch? That should drive the compressor all the time freon low or not. Perhaps these newer systems have a second switch. I would go for help at an AC shop and ask some questions, if it is low on freon, the leak needs to be found and corrected anyway.

 

It has Low and High pressure switches. If you are lo on refrigerant it will cycle on and off like you describe. Time for a leak test and fix then fill.

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