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2000 Cherokee A/C

poppyseed

poppyseed

NAXJA Forum User
Location
Ferndale, WA
So I dropped the jeep off at an A/C specialist today for my compressor constantly cycling on and off. He pulled a shim and after diagnosing determined that the Mechanical Fan Clutch needs replaced. He says when the jeep is idling the compressor is running but the system is exceeding 300psi, causing the high pressure switch to shut the compressor off. Once the system cools down and drops in pressure the compressor clicks back on and this cycle starts all over again. He believes the fan clutch isnt engaging enough to pull enough airflow over the condensor at idle.

What are your guys' opinion of this? Sounds pretty legit to me, but im hesitant to think its something that simple. (he checked refigerant levels, and believes it to be properly filled.)
 
How well is it cooling? Is the cycling your only A/C problem? How frequently does it cycle?
 
Last edited:
I think my cooling is fine when I'm in traffic on an 80 degrees day with the a.c. on I'm sitting a couple millimeters above the middle of the temp gauge. When moving a millimeter below it. And the compressor cycles several times a minute in traffic. Hardly at all on the highway.
 
Sorry I wasn't clear: I meant how well does the A/C cool the cabin now, and if pertinent, before it started cycling so often?
 
Sorry its been cycling since I bought it two years ago. I've had the clutch unplugged so I could still use defrost. And now it cools fine air blows out nice and cool. Just keeps cycling when its in traffic
 
Being its a 2000 the electric fan comes on when it cycles correct? I think mine 'cycles' like that too. I'm no a/c expert but aren't they supposed to do that?

Also, the guy sounds trustworthy, otherwise he might try and sell you on adding freon and everything else instead of just a fan clutch.
 
If the AC cools well going down the highway, but not at slow speeds, it could be the fan clutch. When it's all hot and you turn the motor off, does the fan clutch grab hard when you try to turn it by hand?
 
Yeah cycling is normal but in traffic its so frequent it stops cooling the Freon. Ill check the fan today. They are only 40 bucks so I will probably pop a new one in anyways.
 
Tony_SS said:
Being its a 2000 the electric fan comes on when it cycles correct? I think mine 'cycles' like that too. I'm no a/c expert but aren't they supposed to do that?

Also, the guy sounds trustworthy, otherwise he might try and sell you on adding freon and everything else instead of just a fan clutch.
Click to expand...
Yes the E Fan will cycle on when the A/C is running, and you are driving at low speeds/idling.
 
Well I replaced the fan clut ch with a stock replacement Hayden clutch and it appears to have fixed the cycling issue. The real test will be the next hot day.
 
Well after a highway drive to Kmart to buy a grill it still cycles at slow speeds.... on the bright side my grill is sweet! Bbq at my place tonight!
 
Had this same problem on my 2001. After lengthy diagnosis and trial and error it was the pressure sensor on top of the collector that was bad. $4 from junk yard and it quit cycling on and off instantly. There are 2 sensors that tell the clutch to engage, one on top of collector and one on the hose right behind the compressor. Try this and see if it solves your issue.
 
according to my a/c guy, my high/low pressure switches are working fine. Its the fact my system is building too much pressure in the first place thats the problem. It shouldnt be climbing to 300+psi at idle.
 
the late models cycle the e fan on and off based on the pressure switches. If your pressure is getting that high the efan should be running.

if it is, and it still cycles because high pressure, it may very well be the fan clutch. A made in the usa hayes one is not expensive, and if your junk has the factory one it's probably not working like it should.
 
My 2000 never cycled the Fan with AC on unless the temperature got to 220. With the ZJ fan clutch, it would never turn the E-Fan on with AC because it never got above 210.
 
Miller88 said:
My 2000 never cycled the Fan with AC on unless the temperature got to 220. With the ZJ fan clutch, it would never turn the E-Fan on with AC because it never got above 210.
Click to expand...

that was turning on because of engine temp. The PCM controls the fan based on engine temp and AC system pressure.

If the pressure gets too high in the system it will turn on the fan regardless of temp. This is different than the earlier models that just ran the fan whenever the AC was on.

We just discussed this, somewhere on here is floating a picture of the page from the FSM that details the temps and pressures at which the E-fan will come on.
 
Here's a functional schematic of the 2K & 2K1 AC switches that shows the system pressures at which the Fan and Compressor activate/deactivate.


Copyofjpg20002001SwitchDiagram.jpg
 
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