Cooling Fans, no low speed

[joelmz]

I've been trying to get the two cooling fans on my 97 EVC to turn on a low speed when temp is about 183F (high speed work find with A/C on or over 203F without AC).

When I jump the connections at the Engine Cooling Fan Sensor the fans run on low speed, but when reconnected and warmed up nothing but high speed will turn on.

New parts installed: The (2) Fan Resistors, Engine Cooling Fan Sensor (84-95C/91-102C), Fan Relay, and the (2) 50A fuses for the fans next to the relay.

Logic would say the new Sensor is faulty... but does anyone have any other ideas?

Many thanks.

[mvaska]

you replaced your two 50 amp fuses. did you do that because they were blown? have you checked all your other fuses? specifically related to AC.


"Engine Cooling Fan Sensor" ?

do you mean coolant temp sensor? Or radiator fan switch?

I'd check all the coolant temp sensors & the radiator fan switch.

[Joshwa]

http://tech.bentleypublishers.com/thread.jspa?messageID=304096&#304096

skip down to #4
4 -- Cooling the engine down:
_________________
93 Weekender TDI conversion (AHU)
93 MV TDI conversion (1Z)
Weekender rear cot
Late model cabin air filter on 93
Euro spec bumper install on 93

[joelmz]

Thanks guys...
I thought the 4-wire coolant temp sensor would be OK since I don't have CEL codes stored, the temp gauge works and my scan gauge will read the coolant temp. But I'll check that. I'll also look at how the Engine Cool Down circuit works. The fans will stay on high for about 2-5 minutes after the car is off and the coolant temp is above 203F.

I just checked the AC fuses and they are fine and the system is working. Along with the high speed fans when the AC is on (regardless of coolant temp).

I replaces the 50A fuses because they were old and I was already working in
that area.

The Engine Cooling Fan Sensor: It's in the upper right of the radiator (VR6 motor). A 3-wire sensor. Its switch point for low temp 84-95C fan on/off and switch for high temp 91-102C fan on/off. If I bypass/jump this (take the sensor out of the equation) I can get both fans run on low speed and high speed. The switch is new so i don't think its that.

[nickewilliams]

So, did you ever figure this out?

I have essentially run into the same conundrum (including the same replaced parts) with my 01. I installed a salvaged Fan Control Module today and still have no low speed (except with A/C on or jumping the 3-wire sensor). Low pops on if I cut the ignition before high speed kicks on (but only in 1 fan!). Also interesting, I swear that the fan kicks on if I open and close the hood with the engine warm...