A different CDTi fan problem

[RayH]

In a nutshell 2 speed fan with neither speed working, fan runs if you apply 12v directly.

A bit of background, I bought the car recently and noticed no low speed fan, didn't try high speed at that point.

A couple of weeks ago I took of the silver resistor, found it to be open circuit and replaced it. Re-assembled, still not working, bridged trinary switch - nothing!

As the car isn't my daily I got around to having another look today.
Stripped it out and found if you apply 12v to fan it runs, so no motor issues.

I have 12v on the connector in the wing, so fuse okay and ground on the other connector. I have checked the relays in the fan control box, by removing them and testing with 12v to coil and continuity across switched contacts.

So what am I missing?
Am I right in thinking the trinary switch when bridged by-passes every other control, so I'm not looking at ECU or anything horrible?
The only thing left that I can think of is the PCB in the fan control box itself.

Your thoughts would be appreciated gents - thanks Ray

[RayH]

The other thing I forgot to mention, there is a relay in the fan control box with nothing connected to it.
I'm assuming they used the same box for the old 3 speed fan?

[FrenchMike]

What is marked on the resistor you have fitted ?

[RayH]

Originally Posted by FrenchMike

What is marked on the resistor you have fitted ?

Thanks for the response - it is
Arcol 11.41
HS100 R47 J

[bigbaldbloke]

Have you got 12V and ground at the control box itself? And while you're in the box, are the output wires to the fan and resistor showing closed circuit?

[FrenchMike]

Originally Posted by RayH

Thanks for the response - it is
Arcol 11.41
HS100 R47 J

looks Correct ;could be a faulty relay ? or wrong connection ?

[RayH]

Originally Posted by bigbaldbloke

Have you got 12V and ground at the control box itself? And while you're in the box, are the output wires to the fan and resistor showing closed circuit?

Yes, I should have made that clearer.

In fact if I bridge the relays in turn I get slow speed and fast speed.

While back in there I checked the voltages on each of the relay coils and I have approx 5v on all of the coil contacts.

I didn't notice when I had them out earlier but do they operate on 5v or should there be 12v there?

This voltage is present on all relay coil contacts when the ignition is on, regardless of AC position even with the ATC turned off.

[RayH]

Originally Posted by FrenchMike

looks Correct ;could be a faulty relay ? or wrong connection ?

The relays checked out earlier but they are not being energised.

[T-Cut]

Originally Posted by RayH

So what am I missing?

Fuse 4 in the engine fuse box?
RH row, second down.

TC

[RayH]

Originally Posted by T-Cut

Fuse 4 in the engine fuse box?
RH row, second down.

TC

Nope, just been to check it again in case I did miss it