2003 F-150 5.4L

AC compressor was kicking on and off, indicating low refrigerant. Had AC recharged and it worked great for about 3 weeks. Turned on AC a few days ago and got nothing but HOT air. Worked fine the day before. AC compressor is NOT engaging. I'm not sure what next step to take. I don't fully understand the paper clip jumper. What exactly am I jumping? I've seen mention of a plug and also a relay? If someone has a good video, pics, or how-to, I will try that next unless someone has a better idea?

 

right off the bat, you may have a refrigerant leak going on, I had a leak in one of my shrader valves. it was not discovered as the gauges were on so we did not know that.
take it back to your shop, have it checked out.

 

Take to a shop,have system evacuated and they can tell you if you have a leak. or If you can get gauges and vacuum pump,vacuum down and see if it holds. ONLY DO THE SECOND IF YOU KNOW FOR CERTAIN IT IS EMPTY.

 

The paperclip method is done to bypass the low pressure switch and force the a/c to engage despite a low refrigerant charge. It can be used to get you by with some level of comfort until you can make it somewhere for a repair/recharge, or is otherwise done for quick testing purposes. I think it may be on the a/c accumulator on the passenger side firewall on your pickup. Just unplug the harness from the 2-prong switch and bend a paperclip (or use a piece of wire with the ends stripped) -- push 1 end of the paperclip into 1 side of the wiring harness plugin. And the other end of the paperclip into the other end of the wiring harness plugin. Voila. If the low pressure switch was tripped open before, this should 'force' your a/c on. Running like this risks damaging your compressor and I wouldn't advise it except for a quick troubleshooting. If you know your pressure was fine, then you just did a quick and dirty diagnosis of a bad low pressure switch (an ohm meter would be better, but you can only run what you brung). If you don't know your pressure at all and this turns on your a/c, it's most likely that you simply have leaked your refrigerant out again.

 

Thanks for the suggestions. I don't think it's a leak simply because it was working perfectly when I parked it, then less than 8 hours later there was absolutely nothing. No compressor cycling, no cool/warm air. I don't have manifold gauges and can't get back to a shop until Thursday so I'd just like to eliminate other possibilities in the meantime.

ColdKahuna, thanks for the info. I'll give that a try to see if the compressor engages and go from there.

 

Check fuse 5 under the dash and fuse 13 under the hood.

 

First thing I did. Thanks, though.

 

Jumped the switch and the compressor kicked on. Will get the pressure checked next week. If it's good, I'll replace the switch. Hopefully that's it.

 

95% chance you are low on freon from leak
Pressure switch is rare to malfunction

 

Had similar problem...front part of clutch where it flexes was so rusted it couldn't engage.