What's cause's the a/c compressor to stop?

[ddave]

Well, on a cold start, my a/c blows cold, I mean it works great. 20 minutes down the road, something is shutting down the compressor. If I gun it from a stop or throw it in neutral and rev it up a bit I can get it to come back on, for another 20 minutes.
If I start it up, I can let it idol for as long as 30 minutes with no ploblems at all, the cluth is engaged the whole time. Could it be the high pressure switch?

94 Ford Ranger 2.3

 

[4x4junkie]

If I was going to guess, I would say not enough airflow through the condenser, and the high-pressure switch is tripping.

A worn fan clutch can be a possible cause, as can missing air seals between the condenser & radiator (allowing air to bypass the condenser).

You'd need to get a set of gauges on there to verify for sure what's going on though.

 

[ddave]

Thanks for the responce. I'm going to run out a pick up some gauges tomorrow. I was thinking about the fan myself, but I'm not having any overheating issues. I mean my temp guage barely breaks into the "normal" zone. Can it still be the fan base on that info? Far as I can tell, the fan clutch is the original one.

 

[idriveafordranger94]

A compressor clutch that cycles on and off is normal. If the compressor cycles constantly, the evaporator will freeze up and block all airflow. There is a switch inside the compressor to tell it when to cycle on and off. Sounds to me like normal operation but sounds like you need to hook up some ac gauges to see the pressures and whatnot

 

[ddave]

Thanks guys for the responces. Using process of elimanation, turns out it was the low-side pressure switch. Went ahead a had the high-side switch and the relay replaced as well.

 

[Daniel C]

I don't wanna jack your thread or anything but I'm having this same problem. I replaced my cycle switch and it still blowes hot air out after 20 mins of driving.

 

[floridaoranges]

I don't wanna jack your thread or anything but I'm having this same problem. I replaced my cycle switch and it still blowes hot air out after 20 mins of driving.

Could be the a/c clutch. That what was wrong with mine.

 

[ddave]

Mine was apparently freezing up causing the high pressure switch to do it's job. Replacing low side switch has fixed it now for a week. Wondering if yours is either one of the other two? I,ve read that alot of folks have had similar problems and it turned out to be a stuck relay. I must admit, when I changed the high switch the small schrader valve was bad and I lost all the freon. That was the opportunity to replace all schrader valves. Once we did the vac and recharge, couldn't get the compressor to come back on. So jumped out the low side switch and replaced. Hadn't had a problem since.