no power to A/C Compressor

[dksob81]

I am working on a 2000 Jeep Cherokee 4.0L. Well the guy brought it in because the A/C didn't work, So I checked the pressure and it was low. I evacuated the system, vacuum it down and recharged it to the proper level (1.25lbs) and the compessor is not engaging. then, I jumped the Low Pressure Switch (Clutch Cycling Switch) and nothing, checked the relay and swapped relay with fuel pump and still nothing, checked Fuse = GOOD. I then jumped power from the battery straight to the compressor and nothing still will not engage. When I checked power, using a test light, at the comrpessor and nothing, I then switched it to check for ground and that wire is grounded for some reason, but I still get not power to the harness with it unplugged. So it seems like I have a couple things going on here. Any ideas, Wiring diagrams, which wire at the PCM is the A/C Clutch Wire and which pin at the Relay is for the Clutch Coil.

[fredjacksonsan]

You have power to it, and everything else works....bad compressor?

[dksob81]

No, there is no power at the compressor.

[Saudade]

You should have a low resistance reading fromthe clutch wire to ground. The clutch has a coil that energizes with 12v and engages a clutch just like a relay engages. However, it should not be Zero ohms. So ditch the test light and get a ohm meter and check again.

If you put 12v directly to the clutch and it's didn't engage, then your clutch likely is bad.

How did you fully charge the system without the compressor running?

[dksob81]

We have a robinair A/c Recharge/Recovery machine at work, it will pump in pretty much as much freon as you want and this jeep only takes 1.25lbs,which isn't very much,. so the compressor didn't need to be engaged for it to take it.

Well anyways I got it figured out.today I tested the Relay and the circuit and everything tested fine, I then recharged the system and disconnected the Ccompressor wire and I had battery voltage, but as soon as I reconnect th compressor wire it loses all power. After doing this a couple times the clutch started to spin but real slow and then I could smell it - so it needs a new compressor.

[AlohaBra]

I blew two on my 97....there was apparently debris in mine and it seized the compressor. Recommend replacing the reciever-dryer also ($41).

[dksob81]

yea we will replace the accumulator if the guy wants us to fix his A/C. Our part supplier won't warranty the compressor without the reciever/drier being replaced.