Troubleshooting KV6 fan

Ps3000 · 22nd March 2020, 13:58

Hi Folks
I've done several searches but not found my exact issue yet.

I have changed my old fan for a Jules revotec one. The fan spins fine if I bridge the relay contacts in the control box.
The issue I have is that using the "demist test" the fan isn't energised at all.

My fan is a later negative switched resistor model. There are two relays in the control box and the pos supply to the fan is constant - so my understanding is that the larger relay is the main supply to the fan (on/off) and the smaller one switches the resistor in and out of circuit to make low speed work.

My issue appears to be that even with the ign on, and demist pressed, the large relay is getting no power from the ECU.*

I have checked all the fuses and relays - all seems good. If I bridge the main contacts of the large relay, the fan works OK.

*checked by putting a meter across the coil contacts of the relay.

What next?

(The car has been apart for some time for engine replacement so if something else being disconnected could cause this I'm all ears - I can't see anything but I may have missed something)

SD1too · 22nd March 2020, 15:30

Quote:

Originally Posted by Ps3000

My issue appears to be that even with the ign on, and demist pressed, the large relay is getting no power from the ECU.

Hi John,

On the petrol engined cars you need to have the engine running to successfully perform the demist test.

Simon

Ps3000 · 22nd March 2020, 16:24

Thanks Simon - I had forgotten that - it's been a while.

22nd March 2020, 13:58	#1
Ps3000 Gets stuck in None at moment Join Date: May 2013 Location: Loughborough Posts: 899 Thanks: 230 Thanked 125 Times in 113 Posts	Troubleshooting KV6 fan Hi Folks I've done several searches but not found my exact issue yet. I have changed my old fan for a Jules revotec one. The fan spins fine if I bridge the relay contacts in the control box. The issue I have is that using the "demist test" the fan isn't energised at all. My fan is a later negative switched resistor model. There are two relays in the control box and the pos supply to the fan is constant - so my understanding is that the larger relay is the main supply to the fan (on/off) and the smaller one switches the resistor in and out of circuit to make low speed work. My issue appears to be that even with the ign on, and demist pressed, the large relay is getting no power from the ECU.* I have checked all the fuses and relays - all seems good. If I bridge the main contacts of the large relay, the fan works OK. checked by putting a meter across the coil contacts of the relay. What next? (The car has been apart for some time for engine replacement so if something else being disconnected could cause this I'm all ears - I can't see anything but I may have missed something) Last edited by Ps3000; 22nd March 2020 at 14:11..*

22nd March 2020, 16:24	#3
Ps3000 Gets stuck in None at moment Join Date: May 2013 Location: Loughborough Posts: 899 Thanks: 230 Thanked 125 Times in 113 Posts	Thanks Simon - I had forgotten that - it's been a while.