Radiator fan speed question 05 jetta waggon 1.9 tdi BEW.

Winning

Well-known member
Joined
Aug 9, 2021
Location
Southern California
TDI
2005 Bora Wagon
Vheicle 2005 vw jetta wagon 1.9 tdi pd BEW.

So i noticed my coolant temps are climbing higher than they should using vcds. They climb as high as 99c on a long steep grade.

I went to test my radiator fans and the fan relay box.
First test ignition on engine not running ac button on and interrior fan on. Radiator fans turn on.

The next test i ran was jumping at the Radiator fan speed switch on radiator.

One of them runs the radiator fans and they will run untill i disconect the jumper. This one will run with the ignition off, with the ignition on but engine not running and with the ignition on and engine running.

The other wire when jumped with the engine off and the key off will do nothing. But with the ignition on and the engine running or the ignition on and the engine off it will start the fans for a few seconds then the fans will stop running and when the jumper is remove the fans will start again and then turn off again after a few seconds. So the other wire only temporarilay kicks on the radiator fan only if the ignition is on. I can hear the fan relay kick on and off temporarily running the fan on contact and when the wire is disconnected. Is this normal? Or should one be a high fan speed continuous when jumped and the other be a low speed continuous when jumped regardless of ignition position?
 

Vince Waldon

Top Post Dawg
Joined
Apr 25, 2009
Location
Edmonton AB Canada
TDI
2001 ALH Jetta, 2003 ALH Wagon, 2005 BEW Wagon
My own personal experience:

- every t-stat I've ever installed (6 ALHs / BEWs) was stamped with "87C"
- every ALH/BEW I've driven runs at 88C - 90C normally, pushing to 91C-92 if facing headwinds down the highway, mild to moderate hills etc.
- exception to those temperatures being a hot summer Edmonton day in traffic, where when temps edge up to 98C the cooling fans come on and the engine cools back to about 93C before the fans shut off. Lather/rinse/repeat.
- same temperature climb if pushing hard on a long grade, say up to a ski/mountain biking hill, except that the temps will stay up around 98-99 'cause the car is already moving and so the rad fans don't add much joy. Likewise summer traffic if the A/C is on, as the fans are already running.

Have never seen past 99C, have never worried about it as the system is pressurized to handle temps way beyond 100C *and* there's a warning light on the dash that will tell me to pull over if need be. :)

Just my personal experience.
 

Winning

Well-known member
Joined
Aug 9, 2021
Location
Southern California
TDI
2005 Bora Wagon
Sure, if your thermostat is stuck open. Nominal thermostat opening temperature is 90C.

Follow this guide to test your fans:

I will go through all the fan tests in the order of that trouble shooting guide and get back to you. I did them all yesterday thoug a bit diffrent order. I suspect something is up with ether the high or low fan setting through the fan realy when the fan heat switch plug at the radiator is jumped.
 
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