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chudsy 10-21-2013 08:46 AM

Hydraulic Fan Behaviour
Hi All,
I've been reading around and just wanted to confirm a few things.
When I start the engine the fan spins for about 5-10 seconds then stops. The only other time it kicks in is when I hear it running when it gets up to temp. It never goes over halfway on the gauge.
It also doesn't spin up when I switch on the A/C.
It doesn't sound normal behavuiour from what I've read but the Jeep doesn't overheat.
Anything simple I could look at - I was thinking of the P/S fluid levels to start with?

Frango100 10-21-2013 10:29 AM

Re: Hydraulic Fan Behaviour
The hydraulic cooling fan should spin with approx 500 rpm as soon as you start the engine. Did you try to turn the fan by hand, to feel if its spinning freely? There is a bit of resistance, but not too much.
If you switch the AC on, then the fan not necessarily should spin faster, this depends on a pressure signal from the AC pressure sensor.
How is the power steering, does it feel normal?

chudsy 10-21-2013 11:05 AM

Re: Hydraulic Fan Behaviour
Hi Frank,
Steering seems fine - occasional noise when doing a tight slow turn in the parking lot but that's all.
I'll check the fan for free spinning before I start it to when I go home in an hour and report back - I'll have a quick look at the fluid level while I'm there as that will be cooled off as well.
I'll let you know a bit later. :thumbsup:

hoffmanestates 10-21-2013 06:45 PM

Mine runs the same. I disconnected the temp sensor behind alternator and after few seconds it goes full balls. So I know its working.

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chudsy 10-22-2013 04:16 AM

Re: Hydraulic Fan Behaviour
Plenty of fluid and spins freely.
I'll check the trick you did Hoffman - cheers!

Frango100 10-22-2013 08:54 AM

Re: Hydraulic Fan Behaviour
You already heard the fan ramping up when the engine gets hot, so removing the temperature sensor connector for sure will let the fan go to full speed. When the PCM looses the coolant temperature signal, it has no idea anymore what the coolant temperature is and as a failsafe it will send a full open signal to the control solenoid on the fan assy. You will only end up with a check engine light and a fault code related to the hydraulic cooling fan solenoid, which has to be reset afterward.
If you start the engine and accelerate it a bit, will the fan then start to run?

chudsy 10-23-2013 10:12 AM

Re: Hydraulic Fan Behaviour
I'll have a look after Frank - I've only checked at idle so far when it's cold.

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