Cooling Fans Stay On ???????

[jgibson22]

I have a 01' New Beetle my cooling fans come on high speed when the ignition is turned on and stay on while the motor is running. Have already changed out the coolant temp sensor, control module, radiator switch, and two wire switch between the radiator and the motor, I think it is the thermal switch. I think I have narrowed it down to whatever controls the #10 relay in the thirteenfold auxiliary relay panel, ALLDATA calls it THIRD SPEED COOLANT FAN CONTROL (FC) (100). If I disconnect this relay with the ignition on, the fans shut off or if I unplug the two wire ?thermal switch? the fans go off. I need to know what controls the #10 relay, or can anyone help with why the fans would stay on high once the ignition is turned on and while the engine runs or not.

[woozyjon]

I am running into the same problem with my '00, i'am about the replace the 2 wire switch you are talking about, Dealer called it the AC Fan relay switch......

Jon

[jackfrost]

is it doing this with the ac on or off?

[simonsi]

3rd fan speed ONLY runs with the ignition on due to the high battery drain. It has its own thermal switch as you have found, that is what controls it.

With the ignition ON you have 12V to the thermal switch, with a cold rad you should NOT have 12V getting past the thermal switch to the relay.

The 3rd speed does not go via the Fan control module so that has no influence.

I´d say you have either:

• a shorted thermal switch or
• a stuck relay or
• a shorted 12V to the relay coil + side

there is nothing else in the circuit

[mvf209]

I have the same problem with my 2000 1.8T. Can anyone tell me where the thermal switch is? I've replaced everything else.

[persiano_dubai]

I had the exact same problem and I changed the CONTROL MODULE and THE FAN as well and issue was solved

[MyOtherRidesAVette]

Originally Posted by mvf209

I have the same problem with my 2000 1.8T. Can anyone tell me where the thermal switch is? I've replaced everything else.

I read your thread, I know you have already replaced the module and the "radiator fan switch". If someone can please put up a wiring schematic, and you have a multi-meter, I can help you track down the culprit.

MORAV

[mvf209]

Try unplugging the AC cutoff switch located in the upper radiator hose near the radiator. It looks similar to the coolant temp sensor.

[Bugg1n]

Originally Posted by mvf209

Try unplugging the AC cutoff switch located in the upper radiator hose near the radiator. It looks similar to the coolant temp sensor.

x2

Mine went bad 3 times during my 10-yrs of ownership. Unplugging that sensor/switch is a sure-fire way to tell.

[IndyTom]

Okay, now I have the same issue as everyone above mentioned.
My 2000 Beetle 1.8T just decided to run the fans at high speed at any time the ignition is on regardless if the engine is hot or cold or the AC is on or not.

I see a lot of people trying and suggesting but I don't see anyone that had the actual problem post back and let us know what finally solved the issue. It's great that they found a solution but it would be even greater if they would share and not keep it to themselves.

Thank you.



PS: Is this the switch you guys were talking about when you said the A/C cut off switch?? I could not find a so called "A/C cut off switch" but I did find a A/C Intake Duct Temperature Sensor.
Just wanted to see if that is what you guys were referring to.

Hella A/C Switch - Direct OE Replacement
1998-2006 Volkswagen Beetle
Fits: w/ Electronic Regulated A/C Intake Duct Temperature Sensor.
Type: Direct Oe Replacement

[IndyTom]

Originally Posted by Bugg1n

x2

Mine went bad 3 times during my 10-yrs of ownership. Unplugging that sensor/switch is a sure-fire way to tell.

Okay, I pulled the plug off this sensor and the fans did shut off. So I think this is the culprit. Now the only thing left to do is to order one and replace it. Question, what exactly is it called and does anyone have a part number. I could not find anything listed under an Airconditioning Cut off switch. If someone knows the proper term and perhaps even knows the part number for this sensor I would be forever grateful! Thank you!!

[IndyTom]

Did you ever find the actual cause and did you get it fixed? I am having the exact same problem and I did replace the regular green temp sensor and the 2wire AC/cut off switch. I also changed the fuses on top of the battery which were fine btw but Just in case I replaced them with new ones. If I unplug the AC/Cut off switch the fans stop but replacing it with a new one didn't fix the issue. Not sure what else to try. Please HELP!

Tom in INdy
2000 NB GLX 1.8T

Originally Posted by jgibson22

I have a 01' New Beetle my cooling fans come on high speed when the ignition is turned on and stay on while the motor is running. Have already changed out the coolant temp sensor, control module, radiator switch, and two wire switch between the radiator and the motor, I think it is the thermal switch. I think I have narrowed it down to whatever controls the #10 relay in the thirteenfold auxiliary relay panel, ALLDATA calls it THIRD SPEED COOLANT FAN CONTROL (FC) (100). If I disconnect this relay with the ignition on, the fans shut off or if I unplug the two wire ?thermal switch? the fans go off. I need to know what controls the #10 relay, or can anyone help with why the fans would stay on high once the ignition is turned on and while the engine runs or not.

[IndyTom]

Originally Posted by simonsi

3rd fan speed ONLY runs with the ignition on due to the high battery drain. It has its own thermal switch as you have found, that is what controls it.

With the ignition ON you have 12V to the thermal switch, with a cold rad you should NOT have 12V getting past the thermal switch to the relay.

The 3rd speed does not go via the Fan control module so that has no influence.

I´d say you have either:

• a shorted thermal switch or
• a stuck relay or
• a shorted 12V to the relay coil + side

there is nothing else in the circuit

Okay, I switched out the Temp Sensor and the Thermal Sensor/AC Cut off switch but my fans are still blowing at 70 mph. You say it isn't the fan control module but perhaps a stuck relay? Which relay is it and how do you get it unstuck? And I have no idea what that number 3 on you list means. shorted 12V to the relay coild + Side??? Either way I am stuck and getting sick of those fans blowing like crazy. It adds to the already high wind noise of this car. Plus it can't be good for the fans to run them constantly like that on full speed.

[IndyTom]

Originally Posted by persiano_dubai

I had the exact same problem and I changed the CONTROL MODULE and THE FAN as well and issue was solved

The Fans could very well be the problem. From other similar posts on other forums one person finally gave up trying to replace every single part that it could or could not be and took it to the dealer. They first changed out the fan control module but that didn't solve his problem. They couldn't find the cause so they got in touch with VW and they told the dealer that it more than likely the fans themselves are to blame. They have a resistor/thermostat built in which is prone to go bad. I have pretty much replaced everything I can think of but the damn fans are still running at Super High Speed every time I turn the ignition switch to the on position and don't switch off until I turn off the car. I finally couldn't stand it any longer and disconnected the Termal/A/C cut off switch. This stopped the fans but if I sit in traffic with or on a stoplight the temp does reach over 200 degrees which can't be good either. So, I will probably save up and replace those damn expensive fans to see if that will finally solve this mystery. The only other thing someone else suggested is to replace the AC High/Low Pressure Switch or Thurst Sensor. If it is busted it could give a high pressure reading on the AC system which in turn puts the fans into High Speed mode. It is amazing that even with all the computer diagnostic equiptment we still have to guess and replace all sorts of parts praying that one of them will actually fix the problem. Geesh! What a racket.

[IndyTom]

:thumbup: Well, after 2 weeks I finally fixed the issue with my '00 Beetle 1.8 The cooling fans started to run on Super High speed the moment you turned on the ignition (even without starting the car) and they remained on Super High Fan Speed the entire time until you shut off the ignition.
I swapped out the "Green" Temp Sensor and I also ordered a "AC Cut out/off switch from ECS tuning. When I replaced that switch I noticed the one that I pulled was "Black with a Green Stripe on the top rim" The one that ECS sent me was "White" in Color. I didn't think anything of it since they look totally identical besides the color. They both had 2 pins and the plug fit perfectly on the "White" Switch. Anyway, I turned the ignition on and there goes the fans again at Turbo Speed. Damn, I thought for sure that was it. Well, I came to think that perhaps there is more than just the different color to that switch. I cleaned off the old switch and was barely able to read the part number off. I plugged it in as a Search on ECS Tuning and BAMM there it was. Black Switch with Green stripe just like the one I took out of my 1.8T Beetle. I went ahead and ordered the part just to give it a try. It came in today, I swapped it out and guess what. Problem Solved. The fans remain off when turning the ignition to the 2nd On position and only come one when they are suppose to now. WOW, and I already ordered a Fan Control Module and a new Fan Assembly from Amazon which hasn't arrived yet. Now, I can send those things back and save me about 200 bucks. Amazing that that little part can cause so many headaches. Okay, so let me give you the part number of this switch. It's not an AC cut off switch but is called a 2 Pin Thermal Switch 112c
The OEM Part number is: 357919369F Here is the link to ECS for this part:
Home Page > Search > 357919369F > ES#248948 2-Pin Thermal Switch - 112C* - 357919369F
You can find that switch on the Drivers side towards the radiator/fan shroud where the upper radiator hose and two smaller hoses come together and where those 3 hoses meet. This is where the switch is located and it's and easy 2 minute swap. I didn't even loose any coolant since I had it sitting in the garage overnight and there was no pressure in the line. If you order the switch be sure to also order a new O-Ring they don't send you one with the switch and they really should.

Anyway, I just wanted to report back and let everyone know that my little big problem has been solved You all have a great weekend!

Tom in Indy
'00 Yellow Beetle 1.8L GLX

[LiftedBeetle]

Thank you Tom for coming back to let everyone know that the problem is fixed AND how you fixed it. It is so frustrating reading through pages of troubleshooting threads only to find no answer at the end. My NB has had this problem for about 2 weeks now (fan on full speed as soon as you turn on the ignition) and it's driving me crazy!

Will report back after I buy and install the switch you linked to.

[IndyTom]

Originally Posted by LiftedBeetle

Thank you Tom for coming back to let everyone know that the problem is fixed AND how you fixed it. It is so frustrating reading through pages of troubleshooting threads only to find no answer at the end. My NB has had this problem for about 2 weeks now (fan on full speed as soon as you turn on the ignition) and it's driving me crazy!

Will report back after I buy and install the switch you linked to.

It drove me crazy until I finally replaced that Thermal Switch. I am borrowing a pic from D2Beetle. The 2 pin switch is in the GREEN Circle.

[LiftedBeetle]

Great pic! Just went out and started the beetle, unplugged that switch and sure enough, the fans turned off. You've been a huge help Tom. The switch is ordered and I'll make sure to report back once it's installed

[IndyTom]

Originally Posted by LiftedBeetle

Great pic! Just went out and started the beetle, unplugged that switch and sure enough, the fans turned off. You've been a huge help Tom. The switch is ordered and I'll make sure to report back once it's installed

Keep us posted! I am sure it will be fine once you replace that troublesome Switch.