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JEREMY74 · Joined: 19 Oct 2012 Posts: 20 Location: Illinois

when i drove into the garage and parked the other day i noticed the radiator fan was still running. it was pretty hot outside and i know this is normal to run after you turn the car off to cool the motor down. i went inside the house for 60 minutes or so and came back out and it was still on. i disconnected the negative battery cable so it wouldnt drain my battery. the battery has full charge now. if i hook up the negative cable back to the battery the fan starts back up. do you think this could be a stuck temperature thermostat relay? i cant figure out witch relay this would be. i know where they are located. any help is greatly appreciated since this is my daily ride to work. just turned over 100k on the milage. thanks.
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1987 PORSCHE 924S

edredas · Joined: 09 Dec 2004 Posts: 861 Location: Charlotte, NC

Try pulling one of the wires off the the thermo temp switch on the radiator. If the fan turns off, then the switch is bad.

Here is a more in depth troubleshooting guide for the cooling fans.

http://www.clarks-garage.com/pdf-manual/cool-01.pdf
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'84 944 -White, Brown interior
'84 944 -Red, Automatic
'86 944 -Garnet, Fully loaded, Koni suspension
'87 924S -Red, 300hp 951 swap
'87 924S -Red, Project Car
'88 924S -Red, Daily Driver

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

if fan is running full tilt with key off "ac relay" is bad
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

JEREMY74 · Joined: 19 Oct 2012 Posts: 20 Location: Illinois

i pulled both wires off of the thermo temp switch on the radiator and the fan still runs. i also took out the ac relay and the fan still runs.
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1987 PORSCHE 924S

JEREMY74 · Joined: 19 Oct 2012 Posts: 20 Location: Illinois

only the passenger side fan runs
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1987 PORSCHE 924S

JEREMY74 · Joined: 19 Oct 2012 Posts: 20 Location: Illinois

i took out the cooling fan relay the first relay on the top left side and the fan stopped. the relay must be stuck on. ive got a new one on the way and will post if this does the trick. thanks you guys for the assistance and direction.
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1987 PORSCHE 924S

Paul · Posted: Sat Jun 28, 2014 12:16 pm Post subject:

Check the wires that go to the fan switch for shorts to ground. Only one should be 0 ohms to ground. If both are grounded, fans will run. Sometimes the spade connectors' insulation at the fan switch is damaged and causes a short to ground. Sometimes the insulation on the wiring is damaged.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

JEREMY74 · Joined: 19 Oct 2012 Posts: 20 Location: Illinois

ok. ill check that also. thank you paul. i was waiting on the new relay to arrive. ill let you know what i find.
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1987 PORSCHE 924S

JEREMY74 · Joined: 19 Oct 2012 Posts: 20 Location: Illinois

it was the relay. i put the new one in and its running fine now. thanks for the input guys.

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1987 PORSCHE 924S