milmat1

The A/C compressor clutch on my 2000 XJ-4.0 Cycles on/off on/off Constantly. Does not matter if I have the heater selected or the Air selected it still does this.
Really annoying when setting in traffic because the idle speed changes.

What controls the clutch on/off ? And why would it be doing this??


Any Idea??

mike37

do you have climate control
I don't know a lot about the newer jeeps but a lot of newer cars use the
AC in combination with the heater for climate control

my f250 is like that

Carl

As long as you have the switch in any A/C position or defrost it will kick on.

milmat1

But it should stay engaged right ? At least for some amount of time, This thing cycles on and off at about one second on then one second off, Over and over again. And the A/C is not very cold. It was very cold last summer.
I don't know if theres a problem with the compressor control not allowing it to cool, Or if the constant cycling of the compressor is a seperate issue or what??

Carl

Sounds like low freon, charge the charge of refrigerant.

Uncletruck

Yes, if the refrigerant is low the clutch starts cycling on and off rapidly, and it will eventually not come on at all once it gets too low.

Had this problem with my '00, had to keep recharging it. Has a leak in the evaporator core that is not fun to fix.

-UT-

milmat1

Thanks Guys !!

I done some research on this usin g the manual I found here :http://www.greatlakesxj.com/tech.html
And it seems your correct, The first thing is to check the Refrigant level/Pressure..

Thanks !!

milmat1

FYI everyone:

The Clutch Relay is operated by the PCM (Powertrain Control Module). However there are inputs from The Low Pressure Switch (located on the Accumulator) And a High Pressure Cuttoff Switch(located on the discharge line near the compressor) that control whether or not the PCM turns on the Clutch relay as well.
If the Refridgeant level is low, The PCM / Low pressure switch will cause the clutch to cycle as mine was doing!..

The PCM turns on the relay by grounding the negative side of the relay coil...

The Low Pressure switch should Turn on (Close) At approx 34 PSI.And will Turn off (Open) at 20 PSI...
Very low Ambient temps ( > 30*F) will also cause the switch to open and turn off the clutch relay.

Just some info I found while researching this problem, Feel free to copy or paiste it whever it's needed..

Matt

manxman25

My a/c clutch is not activating - despite the fact that the wire going to the clutch has 12V it will still not turn on. This problem only occurs when the engine is HOT. if the engine is cold the clutch will work just fine. Eventually when running the keep for several miles it will kick off and not come back on until the engine cools down. Is the clutch shot? As i said there is power to the clutch so all the relays/switchs are working correctly and the air blows cold

98 JeepJeep

mine wouldnt turn on at all...i had a can of the 134a laying around...a couple of shots of that and it came right on. however it isnt very cold at all. Im going to have it all the old 134 taken out and all fresh put in.

JeepingDan

Means it needs a recharge