Cooling fan runs constantly
Thread Starter
8th Gear
Joined: Oct 2009
Posts: 8
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Cooling fan runs constantly
The cooling fan on my '85 runs from the time it is started til you shut the engine off. I replaced the temp sensor under the thermostat because it was throwing 2 codes(housing was cracked), but that didn't stop the fans from running(did cure the codes). Any idea on what the problem could be. I'd like to fix before the winter sets in, any ideas would be appreciated. Thanks.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
'85 only is supposed to have a seperate switch in the head for the fan that works as a over ride to the computer control.
If that was bad could run fan full time.
Also A/c pressure switch turns on fans ; if fault / bad connection same effect
If that was bad could run fan full time.
Also A/c pressure switch turns on fans ; if fault / bad connection same effect
Le Mans Master
Joined: Nov 2006
Posts: 5,032
Likes: 204
From: Greenwood Indiana
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Not sure, but I would imagine that the fan has a relay to send power to the fan. It could have burned contacts that are stuck in the "on" position.
I know there are 2 fan relays on my 94, (one for each fan). I don't have the 84 here to check how the old ones were wired.
A new fan relay at Autozone: Santech/Relay - Radiator Cooling Fan Motor
Part Number:
MT0498
Price:$16.99 .
I know there are 2 fan relays on my 94, (one for each fan). I don't have the 84 here to check how the old ones were wired.
A new fan relay at Autozone: Santech/Relay - Radiator Cooling Fan Motor
Part Number:
MT0498
Price:$16.99 .
Last edited by johnnymo63; Nov 30, 2010 at 02:38 AM.
Instructor
Joined: Mar 2010
Posts: 216
Likes: 4
From: Shrub Oak NY
My '84's fan runs whenever the ignition switch is on, too. the relay is good and is being energized. I have not looked into it yet, its the least of my problems. I did buy a new GM fan relay because my relay's power contacts failed. The new relay came in the box with black grease all over the terminals. I plugged it in and the fan did not run. Looked at the relay closely and found that the black grease had all dried up dead hard. Had to soak with solvent and chip it all out. The relay was made in China. Bet the inspectors never thought to check the grease composition. Stuff we used to take for granted with American made goods isn't so simple with foreign stuff, like those impropoerly heat treated Chinese brake rotors that warp so soon.
