Strange radiator cooling fan behaviour

Geoff130 · 1st July 2019, 12:15

My ZT190 has recently had a new water pump as it was leaking a small amount of coolant ( approx. 1/4 litre every 150 miles) and the pink stains where quite obvious (once the cambelt cover was off). It still got hot in stationary traffic though (up to 105 degrees). I checked quite few threads on fan testing and all seem to agree that with demist selected the fan should run. TOAF could turn on full speed but med and low didn't work. I had the bumper off and found a two wire fan and a silver spacer between two wires. I replaced it with a gold resistor and by manually shorting the contacts in the relay box and both high and low speeds work fine, there is no provision for medium. Having put everything together again and checked the operation from the ECU plug by forcing the power on using pin7 and the high and low speeds both working fine. The strange thing is it still won't work on med or low from TOAF nor on demist (ign on). Am I doing this wrong.

SD1too · 1st July 2019, 12:58

Quote:

Originally Posted by Geoff130

... it still won't work ... on demist (ign on). Am I doing this wrong.

With the petrol engines you need the engine running Geoff. Try that and let us know what happens.

Simon

Arctic · 1st July 2019, 14:14

Hi Geoff.
As above start engine, make sure all the A/C is in the off position, press demist only then check through the front grill that the cooling fan is running continually, there is no medium speed on a two wire 2 speed fan with silver/gold resistor.

Geoff130 · 1st July 2019, 16:57

Thank-you both, with the engine running and de-mist selected the fan is behaving as it should.

1st July 2019, 12:15	#1
Geoff130 Loves to post MG ZT 190, Rover 75 CDTi, Honda VFR 750, Honda CB550F Join Date: Aug 2010 Location: Derby Posts: 393 Thanks: 75 Thanked 36 Times in 28 Posts	Strange radiator cooling fan behaviour My ZT190 has recently had a new water pump as it was leaking a small amount of coolant ( approx. 1/4 litre every 150 miles) and the pink stains where quite obvious (once the cambelt cover was off). It still got hot in stationary traffic though (up to 105 degrees). I checked quite few threads on fan testing and all seem to agree that with demist selected the fan should run. TOAF could turn on full speed but med and low didn't work. I had the bumper off and found a two wire fan and a silver spacer between two wires. I replaced it with a gold resistor and by manually shorting the contacts in the relay box and both high and low speeds work fine, there is no provision for medium. Having put everything together again and checked the operation from the ECU plug by forcing the power on using pin7 and the high and low speeds both working fine. The strange thing is it still won't work on med or low from TOAF nor on demist (ign on). Am I doing this wrong.

1st July 2019, 14:14	#3
Arctic Give to Learn Freelander 2 Join Date: Aug 2010 Location: West Midlands Posts: 18,696 Thanks: 1,155 Thanked 6,407 Times in 3,874 Posts	Hi Geoff. As above start engine, make sure all the A/C is in the off position, press demist only then check through the front grill that the cooling fan is running continually, there is no medium speed on a two wire 2 speed fan with silver/gold resistor. __________________ Arctic Givology Learn to Give Everything is Achievable ad altiora tendo. Check out our Nano meet dates http://www.midlandsnanomeets.co.uk/ http://www.the75andztclub.co.uk/index.php?thepage=howto " You do the work , we supply the expertise "

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1st July 2019, 16:57	#4
Geoff130 Loves to post MG ZT 190, Rover 75 CDTi, Honda VFR 750, Honda CB550F Join Date: Aug 2010 Location: Derby Posts: 393 Thanks: 75 Thanked 36 Times in 28 Posts	Thank-you both, with the engine running and de-mist selected the fan is behaving as it should.