Fan comes on when car is hot
Our 2001 Jeep Cherokee Sport has 101K miles on it. Aside from a few squeaks when I go over a bumpy road it is running great. Finally the check engine light is not on anymore (turns out it was a tiny section of hose underneath the engine).
But - when the engine gets hot (particularly when we are stopped in traffic) there is a fan that comes on, and stays on, until I am once again going perhaps 40-50 mph again. I recently took the car to DMV for inspection and when I said to the guy - 'this is a great car' - he responded - 'but it seems soo hot'.
Any ideas what this fan is ? Any routine maintenance to keep it from going on ? It has maybe been 2 years since I changed the air filter...
Thank you.
But - when the engine gets hot (particularly when we are stopped in traffic) there is a fan that comes on, and stays on, until I am once again going perhaps 40-50 mph again. I recently took the car to DMV for inspection and when I said to the guy - 'this is a great car' - he responded - 'but it seems soo hot'.
Any ideas what this fan is ? Any routine maintenance to keep it from going on ? It has maybe been 2 years since I changed the air filter...
Thank you.
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
What you're describing is the auxilliary electric fan that comes on when your engine is hot.
Are you running the air conditioning? Defrost/windshield mode engages the A/C.
Are you running the air conditioning? Defrost/windshield mode engages the A/C.
CF Veteran
Joined: Nov 2009
Posts: 8,172
Likes: 17
From: The Republic of TEXAS
Year: 1998
Model: Cherokee
Engine: 4.0L HO
With regard to cooling system maintenance on a 13+ year old vehicle......which list is shorter?
Cooling system maintenance that HAS been done.......
Cooling system maintenance that HAS NOT been done.......
Is the DMV inspector looking at the temp gauge or is he smelling a too hot motor?
Cooling system maintenance that HAS been done.......
Cooling system maintenance that HAS NOT been done.......
Is the DMV inspector looking at the temp gauge or is he smelling a too hot motor?
Last edited by djb383; Jun 25, 2014 at 12:57 PM.
In the last 18 months I have run the A/C for perhaps 10 minutes total. And I have no need to defrost anything either.
Is there a thermostat which operates the 'auxilliary electric fan' that may need replacing ?
The temp gauge looks fine but the car does seem hot at idle.
Last edited by lhpdiver; Jun 25, 2014 at 01:13 PM.
Herp Derp Jerp

Joined: Nov 2011
Posts: 18,251
Likes: 17
From: Parham, ON
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
The fan is controlled by the computer's coolant temperature sensor. Why would you replace it? Do you have proof that your engine is not running hotter than 218 degrees?
Also see djb383's post about maintenance.
Also see djb383's post about maintenance.
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Let me show how naive I am - to diagnose a 'cracked head' you need to do a compression test ?
Also - before heading South in January 2013 we had the entire A/C system replaced by the dealership. (in answer to another post).
CF Veteran
Joined: Aug 2010
Posts: 8,357
Likes: 103
From: Canton, MI
Year: 1999
Model: Cherokee
Engine: 4.0
No - I'm not hearing any whispers. We bought this car new and it has been the most pampered car on the road.
Let me show how naive I am - to diagnose a 'cracked head' you need to do a compression test ?
Also - before heading South in January 2013 we had the entire A/C system replaced by the dealership. (in answer to another post).
Let me show how naive I am - to diagnose a 'cracked head' you need to do a compression test ?
Also - before heading South in January 2013 we had the entire A/C system replaced by the dealership. (in answer to another post).
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