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Unread 03-24-2013, 02:10 PM   #1
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1998 XJ Cherokee 
Join Date: Mar 2013
Location: Warrenton, OR
Posts: 3
Radiator fan constantly running

Hello, I have a 1998 jeep cherokee 4.0L. Recently, it seems after I installed a RC 4.5" lift my radiator fan will run constantly only when the heater is on defrost. When it does that it is not letting the engine get up to operating temp. It will reach around 145-150 degrees.

When its not on defrost and is on another setting it works fine.

I have done a search and based on what I found I dont think it is the relay or coolant temp sensor. Could it be the control switch on the dash?


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Unread 03-24-2013, 02:19 PM   #2
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Location: Columbus, Ohio
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This is completely normal. Your defrost is tied into your AC (Your AC kicks on whenever defrost is selected). Your AC evaporator removes humidity from the air making the defrost function more effective. Your fan kicks on to draw air through the condenser mounted on the front of your radiator. It runs to help condense the high pressure high temp vapor into a high pressure high temp liquid to feed the metering device in your AC system.
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Unread 03-24-2013, 04:13 PM   #3
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1998 XJ Cherokee 
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I'd bet your t-stat is missing or is stuck open. If the stat is there and functioning correctly, actual coolant temp should be well above 145 even with the efan running.
Man Law - hoods should be raised at least once a week.....have a look see.
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Unread 03-24-2013, 05:44 PM   #4
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2000 XJ Cherokee 
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Location: out in the garage - Minneapolis, Minnesota
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Originally Posted by 1998NWcherokee View Post
....I have done a search and based on what I found I don't think it is the relay or coolant temp sensor.
Why not ?

Did you test the relay, coolant temp sensor, and thermostat for correct function ? What were the test results ?

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