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Discussion Starter #1
I really need some help. I have an 02 Jetta 1.8T. I hope someone on here can help me out. When I have the ac on my fans come on then go off about 30 seconds later. My car keeps running hot and I have no idea what is going. I have replaced the cooling fan control module. Right after I replaced it the fans were staying on while the ac was on but now they are back to coming on and going back off. I don't think that they are coming on at all when the ac is off. Does anyone have any idea what I need to do? I am thinking maybe replace the fan control switch but I would really don't just want to start replacing parts if I don't have to. Thanks.
 

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Reseat the small fuses on top of the battery and check the contacts are clean underneath them too. It is possible you have more than one issue - has the thermostat been changed recently.
 

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Discussion Starter #5 (Edited)
Bought the car about 6 months ago. Not sure whats been replaced. When I first got it, it never over heated on me and the fans while the ac was running would come on and go off. I thought this was normal, but I know in most cars when the ac is on the fan runs constant. But when I replaced the coolant fan control module the fans would come on and stay on.That only lasted about a day. Now they won't come on at all. I put back the old control module and now I am getten them to come on and off with the ac on, but only sometime now. The car runs hot in about 5 miles. I have also heard a couple people say when I turn my car off the fans should run for a few minutes after shut down.My car does not do this and has'nt done it since I have owned it.Is this true? I got a new coolant switch that goes in the radiator.I'm going to replace it and see what happens. Any help will be appreciated..

Got the new coolant switch in the radiator in. now my fans come on and stay on with the ac on. when i turn the ac off the fans come on when the gauge gets half way between half and red? That looks to be where the temp gauge is stayen now. Is it possiable that the thermostat got messed up when it got hot the first time..It did'nt get into the red but hot enough when the car starts beeping at me. Do i need to unhook the battary to reset the computer since i put a new electrical device on the car?
 

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You don't have to disconnect the battery. The switch is just a simple switch, it's either off or on. The ECU won't know any difference from the old switch.
You don't have a CEL do you?

Thinking about it doesn't that switch feed directly into the Fan control module and the ECU isn't even aware of it.
 

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If the thermostat is stuck shut the top hose on the radiator will stay cool because there is no hot water passing the thermostat. Engine wil overheat if the thermostat is stuck completely shut.
Have you had your timing belt and crappy OEM water pump changed yet. If you're driving an 02 and it hasn't been done yet then it's probably due. The OEM plastic impeller is notorious for detaching itself from the bearing.


Sorry, missed where you said you don't know what's been done. You probably need an inspection on your timing belt - get the timing belt,tensioner, water pump and any necessary seals replaced at the same time if necessary. It will get expensive in a hurry if your timing belt or tensioner dies.

As for your fans, a quick check is to turn on the ignition (engine off) AC on ,blower position #2 - then both fans should be running in slow speed mode.
 

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Discussion Starter #8
No check engine light is on at this time. How ever before I replace the coolant fan control module the light was on with a code that said something about the performance of the coolant system.

With the key on and engine not running. Ac button on blower motor switch on number 2, fans are not coming on?

I bought the new control module and put it on.but it stoped working so i put the old one back on. Do u think this module had a defect?

I don't know where to go from here. The water is pumping i can feel it through the hose and the top hose is getting hot. I don't think my problem lies in the flow of water just simply the coolant fans are not coming on and cooling like they should.. It seems like this coolant switch I put on is working right, its just like the setting on the thing is way to high? Should'nt the temp gauge stay half way? The fans are now kicking on without the ac but not untill it gets 3/4 of the way hot..very close to the red and I know red is bad..

I really do thank you guys for helping me out..
 

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Do you have the new green style coolant sensor fitted? I guess the next question here is if you are really overheating now or whether the gauge indication is wrong due to a bad coolant sensor.
Do you remember the code for the coolant performance?
 

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Discussion Starter #10
Do you have the new green style coolant sensor fitted? I guess the next question here is if you are really overheating now or whether the gauge indication is wrong due to a bad coolant sensor.

I bought my sensor from roy rogers in memphis,tn.. It is a meyle products part# 1j0959481a


The coolant sensor is the sensor going into the hose right beside the air box? I guess the best way to figure this one out is to go buy a new one and install it? I think that thing only runs about 10 to 15 bucks. Should I replace that and see what happens before I decide to swap this new non working module out or get a REFUND?
 

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Roy Rogers the cowboy guy?

Dunno about Meyle. I'd probably go with the OEM VW sensor , it's cheap enough.
Check Fuse 16 (and fuse 5) in the cabin fuse panel if your radiator fans are doing random things.

Try cleaning the contacts on the old FCM if they are corroded . I heard this cured some peoples problems with it. I also read someone who posted on here that their FCM lit up internally which wasn't good...lol.

Check out this thread and some of the links in it:
http://www.vwforum.com/forums/f15/cooling-fans-staying-40709/index3.html#post326673
 

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Dash temp light flashing, radiator fans cycle fast/off

My 2003 GLS 1.8T flashes the thermometer light when I first start it every morning during cooler months. It will continue to flash unless I restart it after it has been running several minutes and warmed up.

The heat and A/C work fine
Coolant level is fine
The engine temp gauge rises as expected and stays at center (190)
The car has never overheated
Both upper and lower radiator hoses get hot
Recently had timing belt, water pump and thermostat replaced
I recently replaced the secondary air injection (SAI) blower and it works fine
There is no CEL.

Both radiator fans work but are off most of the time and never spin "slow".
Every few minutes they spin up high, run for several seconds and shut down again. It dims the headlights when it does this. This seems to occur more in the summer when the A/C is on, and if I turn the A/C off when they are spinning fast they shut off immediately. I don't know if it ever happens when moving, I only notice when sitting at a stoplight or just idling in the garage. With A/C off, the fans still cycle on and off, but at a much lower frequency, about every 5 minutes (garage temp 50F).

I think the dash light on cold starts and the fan cycling are separate and possibly unrelated issues because the fans cycle whether the dash is flashing or not. From what I have seen, the fix for the dash light is a whole new $215 overflow ball (or a piece of black tape). I added about a half pint of distilled water and re-seated the connector and it seems to be better. Will see tomorrow morning.

Since both fans work, it would seem the control circuit is faulty. My research indicates it is likely:
The fuses or holder on top of the battery (they look fine)
The fan control module T14, located under the battery
The coolant temperature sensor (don't know if mine is green, where is it?)

I've read that shorting the pins 1&2 on the FCM while the ignition and A/C are on (car not running) will force the fans to run slow and jumper on pins 2&3 will run them fast. Not sure how to do this since I think I need to remove the battery in order to get at the FCM.

Any help is greatly appreciated.
 
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