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Discussion Starter · #1 ·
i sold my Jetta 6 months ago and hadnt been on vortex since. This new layout and search function is driving me crazy and i cant find what i need to read.

My sisters car, 3.5 cabby, started to randomly overheat one day. i got her to drive it home and the fans werent kicking on automatically. i can unplug the plug on the radiator and jump the pics and kick them on manually, also i can turn on the AC and recirc and have them come on LOW only when the AC is on.

What else can i check? Would this mean her coolant temp sensor is bad, or the relay box under the coolant bubble is bad. I just need to know what part to order so i can get it back on the road for her.

Thanks a lot!
 

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People don't seem to be posting much help anymore.. Vbulletin sucks. If only low speed works on the fan, I'd be willing to guess that it's the fan control module under the coolant ball. I'd grab one from a junkyard and try swapping a used one out before buying it new though.. Just my .02
 

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People don't seem to be posting much help anymore..
Agreed.

I had a similar issue on my '96 Jetta. Accept mine were turning on and off as they pleased at whatever speed they pleased with seemingly no relation to the cars temp, or the a/c function. It occured right after I replaced my thermostat and flushed the coolant. Turned out to be corrosion built up on the pins directly on the fan motor. Cleaned them up, no problem since.
 

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it should kick on high speed with the AC on.

maybe the 2nd (high) speed is burnt up on the fan itself.. i've seen that happen before.

but.. i'm not sure if a bad FCM could cause (seemingly) the same issue...?

Turned out to be corrosion built up on the pins directly on the fan motor. Cleaned them up, no problem since.
now do you mean on the plug-in pins or internal to the fan motor housing?
 

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The three wire plug into the rad controls when and what speed the fans turn on. All the fan control module is a relay box and a few fuses and fuseable link. So if you can jump pin one and two and the low speeds turn on, and if you jump pins one and three, the high speed should come on.

If you only get low speed and no high speed, two things could be wrong. To test the fan, just hook two wire up to the fan directly off the battery. One pi is ground, one is low speed, one is high speed. So if you can jump out the fan at both speeds, then it's most likely the fan control module. Or the wiring going to the FCM.

If all these check out, then it's most likely the temp switch in the rad (3 wire one)
 

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Discussion Starter · #11 ·
Sallad
The three wire plug into the rad controls when and what speed the fans turn on. All the fan control module is a relay box and a few fuses and fuseable link. So if you can jump pin one and two and the low speeds turn on, and if you jump pins one and three, the high speed should come on.

If you only get low speed and no high speed, two things could be wrong. To test the fan, just hook two wire up to the fan directly off the battery. One pi is ground, one is low speed, one is high speed. So if you can jump out the fan at both speeds, then it's most likely the fan control module. Or the wiring going to the FCM.

If all these check out, then it's most likely the temp switch in the rad (3 wire one)

im betting its the plug into the rad then cause i can jumop the fan via the wires into the plug and get it to go on both high and low, so the FMC must be good, correct?
 
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