4200 High speed fan not coming on

M

metorical

Junior Member
Messages
31
Hi everyone,

I've been lurking around these parts for a few years now, but something has made me come out of the shadows.

My 2nd speed radiator fan isn't turning on. To set the scene, a while ago the fan would stay stuck on even with the car turned off. I could get it to turn off by knocking on the relay in the engine bay. I replaced the relay and all seemed well. Now though, the 2nd fan isn't turning on at all. I've checked and replaced the resistor. Checked the fuse in the engine bay on the firewall. and swapped the relays for the 1st and 2nd speed with the problem staying with the 2nd speed fan. I have also bridged the connection across the relay and can confirm that the fan does indeed operate.

What doesn't seem to be happening is the control voltage to the 2nd speed relay to turn it on. Is there a fuse upstream or another relay? My attempts at finding a wiring diagram have turned up empty handed.

Any help would be gretly appreciated.
 
GeoffCapes

GeoffCapes

Member
Messages
14,000
Are you getting a CEL on the dash?
Do you have a code reader to plug in (if not, it's worth spending a tenner on one).

It sounds like what I had which was the air temperature sensor (£14 part but an absolute nightmare to fit unless you have three elbows on one arm).
 
conaero

conaero

Forum Owner
Messages
34,674
GeoffCapes said:
Are you getting a CEL on the dash?
Do you have a code reader to plug in (if not, it's worth spending a tenner on one).

It sounds like what I had which was the air temperature sensor (£14 part but an absolute nightmare to fit unless you have three elbows on one arm).
Click to expand...

It could be indeed this. The way to fit it is to remove the offside (drivers) front wheel arch liner and go in from there with a deep 19mm socket from memory.

Its like a small spark plus and easy to change going in via the OSF wheel arch.
 
GeoffCapes

GeoffCapes

Member
Messages
14,000
Conaero said:
It could be indeed this. The way to fit it is to remove the offside (drivers) front wheel arch liner and go in from there with a deep 19mm socket from memory.

Its like a small spark plus and easy to change going in via the OSF wheel arch.
Click to expand...

I've a pic somewhere. The 19mm socket is no good as the sensor is larger than the bolt! Had to get a set of crows feet.
 
conaero

conaero

Forum Owner
Messages
34,674
GeoffCapes said:
I've a pic somewhere. The 19mm socket is no good as the sensor is larger than the bolt! Had to get a set of crows feet.
Click to expand...

I had a deep 19mm that I borrowed from the local MOT garage that did it. You can also just lever/smash the plug off with a hammer then get a normal socket on it to remove.
 
alfatwo

alfatwo

Member
Messages
5,517
metorical said:
Hi everyone,

I've been lurking around these parts for a few years now, but something has made me come out of the shadows.

My 2nd speed radiator fan isn't turning on. To set the scene, a while ago the fan would stay stuck on even with the car turned off. I could get it to turn off by knocking on the relay in the engine bay. I replaced the relay and all seemed well. Now though, the 2nd fan isn't turning on at all. I've checked and replaced the resistor. Checked the fuse in the engine bay on the firewall. and swapped the relays for the 1st and 2nd speed with the problem staying with the 2nd speed fan. I have also bridged the connection across the relay and can confirm that the fan does indeed operate.

What doesn't seem to be happening is the control voltage to the 2nd speed relay to turn it on. Is there a fuse upstream or another relay? My attempts at finding a wiring diagram have turned up empty handed.

Any help would be gretly appreciated.
Click to expand...

The second speed rad fan only kicks in if you have the air con switched full on...ie on a really hot day!

Dave
 
M

metorical

Junior Member
Messages
31
Thanks for the replies.

I don't have a CEL up, but really should get a code ready anyway.

So the second fan won't kick in even if the temp gets up past halfway?
 
GeoffCapes

GeoffCapes

Member
Messages
14,000
metorical said:
Thanks for the replies.

I don't have a CEL up, but really should get a code ready anyway.

So the second fan won't kick in even if the temp gets up past halfway?
Click to expand...

Where are you based? I'm sure someone with a code reader could help you out.
 
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