vw cooling fan issue

[Jose Toro]

I’m looking to pick some minds as I’m having an issue that just doesn’t seem right. I’m working on an ’02 vw cabrio 2.0L, I bought the car cheap because it needed a head gasket. I had the head resurfaced and gone through, replaced the timing belt and put things back together. With 65K on it I was curious of the reasoning behind a head gasket so early. Turns out the cooling fans are not kicking on, so I assume it must have obviously overheated. There is a thermo fan switch on the radiator with 3 connections. One’s 12v and the others run to the low speed and high speed circuits. If I jump the 12v connection on the pigtail to low speed, the fan kicks on. If I jump to high speed connection, then that kicks on. This would lead me to believe I have a faulty thermo fan switch since I know its getting hot. I replaced the switch and same issue. I know I’m not the first to receive a bad new part so I picked up another. still the same. Knowing I was able to return them I figured I’d give it a 3rd go around. I looked up the specs on when the switch should activate low speed, ~196 and high speed ~207, then I did the boiling water test with a multi-meter to see if they were in fact closing the circuit between hot, low and high speed. None of them did anything, even with the water at almost 240F. Again I can see a faulty new item, 2 of them is odd, but 3??? Normally that’s the point where I tell someone that they are doing something wrong. There is no way I should have 3 switches that are stuck open. I guess its possible that there was a bad batch and maybe I should just hit another parts store. I’m just trying to save myself from spending $90 on an OE switch.

Topic

[Richard Kirshy]

Faulty batch lots is not uncommon.
Some years back, I went through 3 after market alternators in 2 days on a 1988 cougar.
All 3 had the drive pulley loosen up on the shaft and tear itself apart.
Final solution was to get another from FORD.
Sometimes trying to save a few bucks will cost you more.

[Jose Toro]

You’re right that saving a few bucks could cost you more in the long run, its just tough when an OE sensor costs about 10% of what you paid for the vehicle.

[Richard Kirshy]

I understand …
Then as a possible less expensive alternative, you might try looking for a different manufacturer of the after market sensor.
http://www.rockauto.com/en/catalog/volkswagen,2002,cabrio,2.0l+l4,1389067,electrical-switch+&+relay,radiator+fan+switch,4312
http://www.partsgeek.com/catalog/2002/volkswagen/cabrio/body_electrical/coolant_fan_temperature_switch.html

[skim3544]

I remember working on these cars, the manual says to put the car in service position but I was able to do it just by sliding the fan assembly out from the bottom. Fan and fan thermo switches are first to be checked/replaced. I did the same test by jumping the connections using paper clip to test the fans. If you are still having problem after, I would
1) check the fuse (dark brown color?) When fan burns out it is common for these fuse to burn out.
2) replace the fan control module.

It is really common for these 3 to burn out at the same time for VW. That is nature of the beast. Bad fan thermo switch (I believe this is connected A/C system) usually burn out the fan control module (this is usually located behind the bumper)

[skim3544]

Needless to say, you want to install quality fan thermo switch. A faulty fan thermo switch can burn out new fan control module after the installation. You can get into money pit loop of these three items (fan switch, fuse, fan control module) frying each other out. I normally use good name brand aftermarket thermo switch – this should run you least $20.

[Jose Toro]

[quote=”skim3544″ post=186692]I remember working on these cars, the manual says to put the car in service position but I was able to do it just by sliding the fan assembly out from the bottom. Fan and fan thermo switches are first to be checked/replaced. I did the same test by jumping the connections using paper clip to test the fans. If you are still having problem after, I would
1) check the fuse (dark brown color?) When fan burns out it is common for these fuse to burn out.
2) replace the fan control module.

It is really common for these 3 to burn out at the same time for VW. That is nature of the beast. Bad fan thermo switch (I believe this is connected A/C system) usually burn out the fan control module (this is usually located behind the bumper)[/quote]

[quote=”skim3544″ post=186694]Needless to say, you want to install quality fan thermo switch. A faulty fan thermo switch can burn out new fan control module after the installation. You can get into money pit loop of these three items (fan switch, fuse, fan control module) frying each other out. I normally use good name brand aftermarket thermo switch – this should run you least $20. [/quote]

The thermo fan switch is mounted right on the radiator, there is an a/c cutout switch that turns on the high speed fans when you turn on the a/c. I did pull 2 fan control modules from the salvage yard from supposed running engines, which is right below the coolant tank, bad location if you ask me. I understand that its a gamble, but at $10 for both I figured its worth it as I’ve wasted more money on less important things. My issue, well one of my issues was the switches I purchased from Advanced Auto. The first one seemed no different than my original one, as mentioned on my OP, I bought 3, I tested the others off the car in boiling water and non would close the low or high speed circuit. I went this route because I wanted to eliminate any other vehicle electrical issues that may be present. The 4th one I bought from Autozone, that one had temp specs on the bottom of the switch element unlike the others and it closed the circuit as it should. I installed it, but I was mistaken about which circuit worked when jumped from the terminal. High speed works, but low does not. I tested voltage on the fan harness looking for 12v when I jumped low speed. 12v was present, but the the fan did not run. My assumption is there is 2 circuits internally that operate independently of each other within the fan motor since high works and low does not. I’ll be looking into replacing the motor shortly. I ran the vehicle Fri, Sat and Sun all while keeping an eye on the temp (BT OBD2 adapter and Torque app is a beautiful thing). according to the app, temp would float between 197.6 and 201. From what I’ve found elsewhere on the interwebs, the low speed fan kicks on @198-207 and high speed @ 210-221. Since my temp is sitting at the temp where the low speed fan should kick on, I need to get that resolved to bring the temp down. 197.6 – 201 isnt bad but I’d like to stay lower as its not even hot out, I’m sure it will only get worse as ambient temps rise. Appreciate all the replies. Sometimes its nice just to get confirmation of a thought process.

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