engine cooling fan inop when a/c empty?
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Joined: Apr 2019
Posts: 10
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Model: Cherokee (XJ)
engine cooling fan inop when a/c empty?
I've got a 1998 4.0 automatic Cherokee anyway wiring problems all fixed except no cooling fan I'm going to recharge the ac tomorrow ...everything checks good ive got power everywhere and the relays etc... hot wired the fan works great im really wondering about the computer sense....or out put ill find out more tomorrow.and ill keep you guys posted and gals....
CF Veteran
Joined: May 2012
Posts: 7,965
Likes: 964
From: Lost in the wilds of Virginia
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
Is there a question somewhere in that word salad? 
https://duckduckgo.com/?q=why+punctu...=v171-1&ia=web
https://duckduckgo.com/?q=why+punctu...=v171-1&ia=web
CF Veteran
Joined: Oct 2018
Posts: 1,096
Likes: 166
From: Hunt County Texas
Year: 1995
Model: Cherokee (XJ)
Engine: 4.0L
When the AC clutch engages it activates the E-fan. If there is not enough pressure or too much pressure in the AC system the clutch won't engage and the fan won't activate in that fashion.
The other way the fan comes on is though data from the Coolant Temp sensor. Once coolant temperature hits something like 217 degrees it activates the E-fan. Many folks wire up an e-fan bypass so they can manually engage the fan when they want. The dash gauge isn't exact so 217 can look pretty hot on some gauges making people think the e-fan isn't working right.
The two factory ways the fan operates are independent of each other. In other words even if you ripped the AC system completely out, the coolant temp would still cause fan activation.
The other way the fan comes on is though data from the Coolant Temp sensor. Once coolant temperature hits something like 217 degrees it activates the E-fan. Many folks wire up an e-fan bypass so they can manually engage the fan when they want. The dash gauge isn't exact so 217 can look pretty hot on some gauges making people think the e-fan isn't working right.
The two factory ways the fan operates are independent of each other. In other words even if you ripped the AC system completely out, the coolant temp would still cause fan activation.
Last edited by downs; May 9, 2020 at 11:05 AM.
CF Veteran
Joined: Oct 2015
Posts: 7,517
Likes: 1,626
Year: 2000
Model: Cherokee (XJ)
When the AC clutch engages it activates the E-fan. If there is not enough pressure or too much pressure in the AC system the clutch won't engage and the fan won't activate in that fashion.
The other way the fan comes on is though data from the Coolant Temp sensor. Once coolant temperature hits something like 217 degrees it activates the E-fan. Many folks wire up an e-fan bypass so they can manually engage the fan when they want. The dash gauge isn't exact so 217 can look pretty hot on some gauges making people think the e-fan isn't working right.
The two factory ways the fan operates are independent of each other. In other words even if you ripped the AC system completely out, the coolant temp would still cause fan activation.
The other way the fan comes on is though data from the Coolant Temp sensor. Once coolant temperature hits something like 217 degrees it activates the E-fan. Many folks wire up an e-fan bypass so they can manually engage the fan when they want. The dash gauge isn't exact so 217 can look pretty hot on some gauges making people think the e-fan isn't working right.
The two factory ways the fan operates are independent of each other. In other words even if you ripped the AC system completely out, the coolant temp would still cause fan activation.
My '00 does not. But the high pressure switch will activate the electric fan when the PSI in the AC system rises to a certain level.
But I think that is just an '00 or '01 thing.
CF Veteran
Joined: Dec 2016
Posts: 1,736
Likes: 407
From: Long Island, New York
Year: 2001
Model: Cherokee (XJ)
Engine: 98 stroked 4.7
My friend has a 99 and the a/c will turn on the cooling fan when the clutch engages as prev stated...in my 01 its only based on temp...they took the a/c control out of the picture except for an overpressure of the freon...Mine trips at 221-225 deg coolant temp...that's pretty high on the gauge
CF Veteran
Joined: Jan 2014
Posts: 1,533
Likes: 349
From: District of Columbia
Year: 1998
Model: Cherokee (XJ)
Engine: 4.0
Yup, the 00 and 01 years have a different fan wiring/programming setup than previous years. The coolant temp has to be hotter (+5°?) and the fan follows refrigerant pressure and not A/C clutch engagement, IIRC.
Last edited by IJM; Sep 8, 2021 at 02:53 PM.
CF Veteran
Joined: Oct 2018
Posts: 1,096
Likes: 166
From: Hunt County Texas
Year: 1995
Model: Cherokee (XJ)
Engine: 4.0L
I don't think that is entirely true. I think at some point the they made it so the electric fan does not come on when you turn on the AC.
My '00 does not. But the high pressure switch will activate the electric fan when the PSI in the AC system rises to a certain level.
But I think that is just an '00 or '01 thing.
My '00 does not. But the high pressure switch will activate the electric fan when the PSI in the AC system rises to a certain level.
But I think that is just an '00 or '01 thing.
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