Aux Fan issue

xjoffroad · Oct 15, 2010

What would cause the aux fan cycle every 20 seconds or so on a jeep cherokee? low freon? Need help and suggestions......

JOOP · Oct 15, 2010

aux fan or AC compressor kicking on?

GaryTJ · Oct 19, 2010

either top off the a/c or take the dark blue/pink wire at the fan control relay and ground it so the fan stays on when the key is on.

JOOP · Oct 19, 2010

If your going to "try" and top off your AC you need to evac the entire system and fill it with the proper quantity , ounces. People usually make the biggest and most costly mistake when they "top off" their AC system. Over charging the system can cause the pump to take a ****, blow metal chunks in your system, then you need damn near everything in the AC system. . CHA CHING$$$$$

Lead Foot · Oct 21, 2010

xjoffroad said:
What would cause the aux fan cycle every 20 seconds or so on a jeep cherokee? low freon? Need help and suggestions......

The aux fan kicks on when, (A) you have the AC on or (B) the engine temp is above 210. Your engine could be teetering up and down around that temp so the fan will kick on, cool the engine back down then turn off once lowered. It heats back up, turns on again then cools down and kicks back off. So on, you get the point.

Happens all the time to me while im wheelin. If its doing it on the freeway or even everyday driving your probably running a little warm. Need a new thermostat or low on coolant or need the radiator flushed. If you get muddy alot make sure the radiator fins are clean.

xjoffroad · Oct 21, 2010

Lead Foot said:
The aux fan kicks on when, (A) you have the AC on or (B) the engine temp is above 210. Your engine could be teetering up and down around that temp so the fan will kick on, cool the engine back down then turn off once lowered. It heats back up, turns on again then cools down and kicks back off. So on, you get the point.

Happens all the time to me while im wheelin. If its doing it on the freeway or even everyday driving your probably running a little warm. Need a new thermostat or low on coolant or need the radiator flushed. If you get muddy alot make sure the radiator fins are clean.

none of this is true in my situation. the fan goes on every 20 sec or so. the engine temp doesnt even hit 200 before it kicks on

Lead Foot · Oct 21, 2010

Does it only start cycling only once its warmed up? Maybe its 190 or 200 that it kicks on at. I honestly cant remember. Could also be different after renix.

i noticed that you started mentioning the AC as well. Is that turning on and off? I now own my first XJ with the AC hooked up (not converted for OBA) I thought I heard the aux fan kicking on and off the other morning for no reason as well. But then I noticed it was actually the ac pump. Messed around a little bit and noticed if my defrost is on it will kick the ac pump on and back off in a cycle. Which COULD also cause the aux fan to kick on while the ac is on. Just a guess. But possible.

GaryTJ · Oct 21, 2010

JOOP said:
If your going to "try" and top off your AC you need to evac the entire system and fill it with the proper quantity , ounces. People usually make the biggest and most costly mistake when they "top off" their AC system. Over charging the system can cause the pump to take a ****, blow metal chunks in your system, then you need damn near everything in the AC system. . CHA CHING$$$$$

That's OK. It will fix his fan cycling problem.

zukkev · Oct 21, 2010

xjoffroad said:
none of this is true in my situation. the fan goes on every 20 sec or so. the engine temp doesnt even hit 200 before it kicks on

Hmmmm...I thought I posted in here last night, or early this am...guess not. If it does it very shortly after you fire it up, and you have the defroster (or any mode which uses the windshield vents, your A/C comressor will cycle on & off, which will turn on & off the aux fan with it...normal condition...