WJ Grand Cherokee Radiator Fan stays on with A/C? Why?

TargetOz
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WJ Grand Cherokee Radiator Fan stays on with A/C? Why?

Unread post by TargetOz » June 22nd, 2015, 6:12 pm

Can someone help with info regarding my fan staying on after the A/C is switched on. This happens with the engine hot or cold but always goes off after engine is switched off and restarts. Is this normal. Is the fan relay or temp switch stuffed. Other than the fan staying on like this everything works well, but the car does vibrate a bit when the fan is on full song.
Thanks in advance. Steve.

4wd Hobbit
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Re: WJ Grand Cherokee Radiator Fan stays on with A/C? Why?

Unread post by 4wd Hobbit » June 22nd, 2015, 7:21 pm

Most A/c systems require a fan to be running when the A/C is on. In most cars with is a separate fan to the engine cooling fan but may just be a second engine cooling fan that stays on when the A/C is on.

TargetOz
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Re: WJ Grand Cherokee Radiator Fan stays on with A/C? Why?

Unread post by TargetOz » June 22nd, 2015, 8:42 pm

Thanks heaps for that, but why would they stay on after the a/c is switched off?

4wd Hobbit
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Re: WJ Grand Cherokee Radiator Fan stays on with A/C? Why?

Unread post by 4wd Hobbit » June 22nd, 2015, 9:03 pm

Dunno but you asked why the fan stays on after the A/c is switched on.

"Can someone help with info regarding my fan staying on after the A/C is switched on."

But maybe more relevant to the information you actually want - in my old Discovery V8, it had a engine driven fan and an aux cooling electric fan that also doubled as the A/c fan. If the engine was very hot on switching off (and A/c was turned off) the aux fan would stay on sucking cool air through the radiator - the logic was that this would cool the coolant when the engine was off and the natural thermal circulation processes in the coolant system would still circulate coolant and continue to cool the engine even though it is off. The fan would often run for up to 5 minutes before it turned off - all normal for a Disco but I dont know about a Jeep.

Clarkey16
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Re: WJ Grand Cherokee Radiator Fan stays on with A/C? Why?

Unread post by Clarkey16 » July 5th, 2015, 4:43 pm

Are we talking radiator fan?
If radiator has your WJ got the hydraulic fan or an electric one?
If it is the hydraulic one it varies the speed of the fan by adjusting the resistance to ground of the fan solenoid through the PCM (Power Control Module) according to engine temp. The fan will run at full speed when there is no resistance.
The solenoid on the fan assembly that physically controls the fan speed may be sticking open & only closes when the hydraulic pressure is released. If it is this solenoid it is not available as a spare part from Jeep, only the whole fan assembly. You may be able to pull the solenoid apart & clean it.
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TargetOz
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Re: WJ Grand Cherokee Radiator Fan stays on with A/C? Why?

Unread post by TargetOz » July 6th, 2015, 1:46 pm

Hi Clarkey16,

They're electric and not hydraulic fan. It just seems odd when it gets to 100 on the temp gauge the fan doesn't come on until I hit the a/c button, then it will stay on until I switch the engine off to restart. Maybe it's normal, the other day I pulled up somewhere and restarted, the gauge said it was just under 110 so the fan came on all by itself as it should, but it seemed to stay on. So it looks like maybe the relay is ok, but maybe the temp sender is playing up??? What do you think?

typhoeus
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Re: WJ Grand Cherokee Radiator Fan stays on with A/C? Why?

Unread post by typhoeus » July 6th, 2015, 9:04 pm

Son has a grand Cherokee, that 2nd fan comes one with a/c and goes off when its switched off. sounds like the relay isn't earthed until the fan is running. or similar

Clarkey16
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Re: WJ Grand Cherokee Radiator Fan stays on with A/C? Why?

Unread post by Clarkey16 » July 8th, 2015, 10:43 pm

Yours must be the straight six then :cool:
I'd swap over the relay, it wouldn't be the first relay I came across that would stick on.
You do know where the relay is? Under the DRIVERS side headlight, video is American.
https://www.youtube.com/watch?v=E5K1D1iEQO8
Service Manual http://www.ausjeepoffroad.com/FSM/WJ_Gr ... ee.pdf.zip
This site will be useful to you
http://wjjeeps.com/jmenu.htm
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