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Cooling fan turns off and on when ac is on

F

FlexJ17

NAXJA Forum User
Location
rancho cucamonga CA
2001 jeep Cherokee, I notice engine temps creeping up to 220 with ac on, I checked cooling fan when ac is on and it turns on but only stays on for 7 seconds then turns off again, then turns on for 7 seconds then turns off again over and over ONLY with the AC on, when the AC is off the cooling fan turns on when the temp gets to where it's supposed to for it to turn on
 
Sounds like a problem with the pressure switches or even the PCM, have you looked at the FSM?
 
Is your AC properly charged? If so you could have switch issues but it would point to the PCM.
 
I just got it recharged at a shop last week, when it's running with the AC on the compressor clutch stays going, the fan is the only thing doing the off on off on, however I just touched one of my ac hard lines and it was cold from the freon going through it, I touched the other ac line and it was really hot
 
High pressure switch and the low pressure switch!
 
Start simple and check all connections and wires you can trace. Then swap out the Low and high pressure switches with known goods to see if that changes anything. After that, I hate to say PCM swap but maybe that is the culprit.

Someone else can verify. One line will be cold (but not frozen) and one will be not due to the pressure differences. If one is hot or frozen over, then it could indicate the flow of refrigerant is not regulated correctly. I am not sure if Cherokees have an office tube or expansion valve (its been awhile), regardless they control high and low pressure regulation/flow.
 
Have you tested the Coolant Temperature Sensor to confirm it is within specifications and the sensor wire plug and wire harness are in good condition ? The 2000-01 only runs the e-fan when called upon by the PCM based on the refrigerate pressures or the coolant temperatures.

There was a Technical Service Bulletin about reprogramming the 2000-01 e-fan parameters. IIRC the TSB was to make the e-fan run like 99 and older with the A/C on, the e-fan runs ON/OFF/ON/OFF/ON as long as A/C is engaged.




Below is an A/C diagram put together by CCKen.

.
 
Last edited:
Tim_MN said:
Have you tested the Coolant Temperature Sensor to confirm it is within specifications and the sensor wire plug and wire harness are in good condition ? The 2000-01 only runs the e-fan when called upon by the PCM based on the refrigerate pressures or the coolant temperatures.

There was a Technical Service Bulletin about reprogramming the 2000-01 e-fan parameters. IIRC the TSB was to make the e-fan run like 99 and older with the A/C on, the e-fan runs ON/OFF/ON/OFF/ON as long as A/C is engaged.

...
Click to expand...

Do you know the TSB number? I looked and couldn't find it.
 
I don't know of a TSB# but when I built my stroker (2000 XJ) I had my PCM reprogrammed so the e-fan came on at a cooler temperature.
 
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