[rogrover38]

Hello all ,
Now my mg tf is back on the road I have been driving it around Leeds and notice the engine bay fan has never come on . I have taken off the engine bay sensor connector with the car running and the fan starts up . Just wondered was there a way of testing the sensor to give me piece of mind it works ??? I thought of using a hairdryer on it would this be stupid ? I have a multimeter if this would help me ?

 

[98luke]

You can test the sensor with your multimeter. Select ohms on your meter and connect the meter leads to each of the sensor terminals. Does not matter which way round the leafs are. The sensor is most likely a negative temperature coefficient sensor so as the temp increases the resistance decreases. Try warming gently with a hair dryer although the you should notice a change just by holding the end of the sensor in your hand. Not sure what the resistance value is of the sensor so try different ranges on your meter start with johns as I suspect it is nominally a 1kohm device.

 

[98luke]

Damn autocorrect!!

Start with kohms not johns!!

 

[barkingdog]

Mine hasn't come on in the ten years I have had the car. Also the rad fan, to the best of my knowledge has only come on during an emissions test for the mot.

 

[Chris T]

Take a look at this thread Engine bay cooling fan and switch

I think your TF will have an engine bay sensor as another method was used in later cars.

However as said I wouldn't expect the engine bay fan come on at all at this time of year and don't be surprised that you will hear the fan much regardless of ambient temperature.

 

[AntonyM]

I think mine's come on twice in four years that I've noticed .....

 

[Julian Foulger]

The engine compartment has got to get very hot (VVC 75C) for it to come on - summer and at a standstill

 

[nocturneblue]

My rad fan (TF 2003) always comes on after about 20 minutes or so if I run the car up and leave it idling in my drive. Clearly it should only come on if the car is at a standstill.

Engine compartment fans - I can't recall details but have heard them operate before!

I do recall seeing rust on the engine compartment fan motor cases though when I had the access hatch off a few years ago so I hit them with a wire brush then a bit of primer spray and underseal. The rust wasn't too bad but I thought it was time to deal with it before it got to be a problem.

 

[Julian Foulger]

'My rad fan (TF 2003) always comes on after about 20 minutes'

The discussion above is about the engine bay fan, not the radiator fan which may well come on after 20 minutes.

 

[nocturneblue]

'My rad fan (TF 2003) always comes on after about 20 minutes'

The discussion above is about the engine bay fan, not the radiator fan which may well come on after 20 minutes.

Indeed, I was just responding to a point BarkingDog made about his rad fan apparently only coming on on in one situation that he knows of.