2nd Gen Non-Engine/Transmission a/c compressor on/off/on/off

[JustinLee]

A/C was working great, then I went on a trip for 18 days and now it won't work. The compressor turns on for about 5 seconds then kicks off for 5 seconds on off on off at about 5 second intervals. I felt one of the coolant lines after running it like that for a couple minutes and it was cold. So there should be refrigerant in the lines, right?



Where to start??



Thanx

Justin

 

[B.G. Smith]

Need to hook up a gage to the suction line, the clutch cycling switch opens at about 23# and closes at about 43#. Could be low on refrigerant, cycling switch bad or orifice tube plugged. If the switch checks out ok, try adding a little refrigerant, it the compressor starts to run longer and the suction pressure starts to rise then you are probably just low, it only holds about 28-32 oz. I believe. bg

 

[DieselDoghouse]

As was said you may be low on gas. Best to check with low pressure and high pressure gauges. Low pressure should be ROUGHLY half (in psi) the ambient temp (in °F). High pressure should be at least 3X the low pressure (about) ALL WHEN COMPRESSOR ON. If you're short-cycling use a jumper wire on the pressure switch (snaps into the accumulator tank) to demand constant compressor. Think you have a leak? start at the coils - check the water drain from the evaporator (comes out of cab at firewall) for an oily residue (baad news), check the front and rear faces of the condensor (behind grille) for same. These would indicate a leak that carried refrigerant oil out of the system. You can have a bad pressure switch but this seems less common from other posts. Good luck!!