pledgercraft

2003 ford f150 crew cab v8. fan works, compressor kicks in but short cycles (about 2 seconds) on and off . Not staying engaged. relay clicks with compressor. freon seems good also. but no cold air. temp control works as well as the panel selector.

mbb

"Freon seems good...."

pray tell, how did you discertain this? gauges on system?

Its a classic sign of system empty of freon. You have ~35 psig pressure due to vapor pressure of freon in system, but as soon as compressor kicks on, due to not enough in system the suction pressure drops below the low pres switch cutoff ~28 psig and it stops the compressor.

Jump the low pressure switch and see if it stays running . You will need to do that to recharge anyway. But you ought to find the leak and fix it first....

pledgercraft

LOL! Yeah I just opened the valve for a squirt..lots of pressure definitely enough to keep compressor running. Got to get a refill kit tomorrow to test for sure.

mbb

Pressure in system is same in not running state, regardless of amt of freon in system. Its the freon vapor pressure at ambient temp . You realy need gauges attached when it cycles to see if its high or low pres making it cut out.

Less likely, but bad compressor clutch coil might heat and drop out after a couple sec if shorted internally.

You can apply battery12v straight to compressor with jumper wire to see clutch engage and stay in not running.

pledgercraft

Yep...Low Freon...has leak somewhere...

77Ranger460

Look for oily residue at one of the connections. Ford o rings often leak, but are easily replaced.