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Old 09-04-2018, 07:08 PM   #1
Join Date: Sep 2018
Location: Denver
Posts: 2
Mastership84 is cool... so far.
Radiator fan randomly comes on.

I'm new so hopefully I'm posting this in the right area!.

Anyway. I recently purchased my 1990 lx coupe. It my first time into car building.

So after i had the car parked for about 3 days after purchasing my radiator fan came on. The car hadn't been driven during those 3 days. It ran unntil my battery died. This has happened 2 other times and only once of those 2 times was the engine hot.
I've looked around and some people have said that's it's a "fan timer switch" but I can't find it on rock Auto or any manuals . Any help would be appreciated!
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Old 09-04-2018, 08:35 PM   #2
Join Date: Sep 2018
Location: Columbus, Ohio
Posts: 6
F20BturboCB9 is cool... so far.
The cooling fans are designed to run 2 minutes after the car is shut off IF the engine is above 226 degrees. If it's not they will just shut off normally. If they are coming on randomly it could be a number of things. It could be the fan timer unit, which is located under the left side of the dash. Or, it could also be the temperature switch which is I believe in the thermostat housing. (Or at least I think it's in the thermostat housing, been awhile since I have been around the f22.) Or it could also possibly be the ecu. I think the best way to figure it out is to kind of do process of elimination with it. When it starts to run randomly unplug the coolant temperature switch first. If it shut's off then it's the temperature switch. If it doesn't shut off unplug the biggest ecu connector (Connector A), if it turns off then the ecu is the likely culprit. If it stays on after both of those have been disconnected then it IS your fan timer unit. I guess technically if you had a shorted A/C diode and left both the fan switch and A/C switch on it could also make the fans run, but it should do it all the time and not randomly I would think. Hope this helped.
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Old 09-05-2018, 05:04 PM   #3
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Join Date: Mar 2007
Location: West Chester, Ohio
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fleetw00d is very helpful fleetw00d is very helpful
The lower temperature switch is on the thermostat housing. The higher temperature switch is on the water outlet at the right front corner of the cylinder head where the upper hose goes to the radiator.
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Old 09-20-2018, 03:43 PM   #4
Join Date: Dec 2017
Posts: 1
Siccmade719 is cool... so far.
I would replace both sensors and the thermo all at once. Do they come on at a red light or drive through?
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electrical , electrical problem , fan , radiator , radiator fan

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