Help With Changing Fan Temp Switch N291

[Vince]

Hi All,

 

I am asking if anyone has steps for changing the temp switch identified in TIS as N291, it's the two stage temp sensor for the two electric fans on our V6 giha 4x4 1999.

 

What I have done so far is establish the follwing (mainly by stumbling around in TIS).

 

1) The sensor is on the radiator surround.

2) The 'control module' is the odd box up by the battery and right at the front of the bonnet. This seems to me to actually contain a dual relay module.

 

I turned off the A/C to stop that from causing the demand for the fans to run. And note that fan 2 does not run when the engine is hot.

I applied power directly to the fans, and they both run fine, so there is a problem supplying power to fan 2.

I unplugged connector C320, the connector on the control module with the 4 low current wires, and found that one of the 'demand cooling' connections was a good 13.6 volt, the other only about 11v.

I worked out which wire (pin 2 red/black) would call for fan2 to run (this is the feed from the temp sensor) and pushed the meter probe into the insulation. Put the other end of the test lead to the battery and the control module clicked and fan 2 started running, so that's why I want to change the sensor. I am convinced that the sensor is not supplying a good enough output to fire the relay in the control module.

 

I am new to TIS and they obviously stick to the official methods, but does anyone know if I released the resistor pack bracket, will I be able to change the sensor from below?

 

Regards

Vince.

[Vince]

Any ideas people?

 

I am starting to wonder if the switch actually is there on the radiator, or if it's on the thermostat housing. Microcat shows three sensors on the stat housing, no1 is for the A/C to know the water temp, no2 is for the dashboard gauge, no3 seems to be the fan switch.

 

Would this make sence?

 

Vince.

[Ex-Galaxy person]

On my TDi, the 2nd fan only cuts in when the A/C is on, and I thought this was how it was supposed to work? Not sure if it's the same for a V6.

[Vince]

From the wiring diagram it suggests that fan2 should come on then the second temperature range of the sensor is reached. The air con can turn on fan1, and if I turn on the A/C fan1 runs with the engine cold.

 

I have changed the right hand (brown) sensor on the thermostat housing. But what worries me is that I unplugged the brown sensor when fan1 was running (A/C off) and it kept running, so my vehicle may have the sensor on the radiator too!

 

I tried my VIN in micro cat, and it didn't know it!

 

Vince.

[Coxsey]

Could you please explain what micro cat is?

 

thanks

[Vince]

Hi,

 

Micro Cat is the PC based car parts system used by the trade to locate part numbers and order parts for cars. It shows you blown up diagrams of all the parts of the car, what the bits cost etc.

 

It's what you see on the screen when you go to buy parts, and think 'that looks useful!' wonder if I can get that for home.

If it knew my VIN it should be able to filter out anything that's not on the car!

 

Vince.

Edited May 13, 2008 by Vince