Diesel rad fan dead
 

Hi, any ideas please. I have just replaced my diesel rad fan with a brand new complete unit fitted with a silver resistor, the old unit was dead. Unfortunately the new one also fails to run. I know there is permanent current on the main feed. I have checked both the 15 and 80 amp fuses, both OK. Nothing when setting the demist... I know there is no gas in the aircon as I have also just replaced all of the radiators and intercooler. Are there any other fuses in the glovebox that might cause a problem, haven't had time to check them all? Have not tested the trinary switch, but this would only trigger the high speed anyway? Pretty miffed, spent a fortune on the car and still it plays silly buggers with me! Cheers, Phil

If all other connections are made correctly I would suggest the silver resistor is dead and needs replacing with the gold one.

Was it just the motor parts or the whole fan system? A diesel system is unique and has to be replaced with another diesel system. A petrol system won't work. If you fitted a diesel version, then the resistor has most likely blown.

The MGR resistor controller 2-speed fan inevitably fails because the resistor is underpowered. They originally used a 50 watt type, but fan failures forced them to uprate it to 75 watts. Those also failed, but there was no further development before MGR went bust. So, the 'silver' resistors have to be swapped out by owners for the necessary 100 watt alternatives. It's a simple enough job to exchange the blown unit for the 'gold' 100 watt versions. You can get the 100 watt resistors from electronics outlets like Farnell, from forum traders and from eBay. There are HowTos around the forums as well.

TC

I've had a fault with the control circuit board where the relays are mounted. Swapped it for a good used one and all was well again .

As TC mentioned, the diesels differ from the petrol versions in that they are controlled by a PWM signal which is decoded in the control box.

You can use a petrol fan, but you need to wire it into the original control circuit. Come to think of it, you can use pretty much any fan you want. I fitted a single speed fan from a Rover 214 as a temporary fix years ago, then forgot all about it, and it is still going strong. :}

Thanks all, sorry for delay in responding, have been away with work. The unit was a full housing / fan off ebay, brand new, sold as suitable for 1.8 and diesel! I think I will have to investigate the pcb / connections, I suspect there is a problem here. Thanks for the pointers, at least I still have the old unit if I need to swap PCB's....

Hi Phil,

Sorry, I'm still not clear what exactly it is that you have fitted.

Did you buy a brand new motor with two wires entering the motor housing and the rest of the wiring including control box and terminating in two chunky multi-pin connectors?

If so, what are the markings on the control box lid? Does it say M47R or PWM2?

Was it supplied in genuine packaging and/or with an MG Rover part number?

Simon

If they've supplied a petrol fan then you'll have to swap the wiring between the control box and the car from your old fan as well as using the PCB.
(Petrol fans don't have a PCB and are wired differently between the control box and the car.)

Artic did a post with photos on the differences which may prove useful to help with swapping things over.

Russ