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[Elite Pete]

I got a call off the wife on Tuesday night saying the Omegas battery is dead (which is strange because its new) so I told her how to use the jump leads over the phone. What I noticed was the aircon fans came on without the ignition being on as soon as she connected the leads. I was wondering if I have done something wrong when I took the radiator out to flush it a couple of weeks ago. So where do I go from here.

Thanks in advance

[Kevin Wood]

Hi Pete,

If it's just appeared but was fine since the rad. change I would think the most likely cause is that one of the relays driving the air con fans has stuck in the "on" position.

A temporary fix would be to remove the offending relay from the engine bay relay box. There's a diagram showing which one's which in the engine bay fuse box here: http://www.omegaowners.com/forum/YaBB.pl?num=1176560725.

Any of those relays which are marked as aircon only would be a good start. Just pull them out one at a time until you find the one that stops the fans then let us know which one it was.

I'll have a closer look at the wiring diagrams tonight and see if anything else occurs to me.

If you get desperate, just unplug the fan motors for now.

Cheers,

Kevin

[Elite Pete]

Cheers Kevin  

[Marks DTM Calib]

Pull the two 20A fuses, easier to take out than the relays....

[TheBoy]

Or the rad switch has gone short circuit....

[Kevin Wood]

Is it the auxiliary fans in front of the rad. or the engine fan behind the rad?

Are they running at full speed or half speed and are both running or just one?

Cheers,

Kevin

[Elite Pete]

Is it the auxiliary fans in front of the rad. or the engine fan behind the rad?

Are they running at full speed or half speed and are both running or just one?

Cheers,

Kevin

Hi Kevin

Its the auxiliary fans in front of the rad, both are running and at full speed, my wife was on the phone as I was explaining which jump lead goes where and as soon as she connected the negative I could hear the fans and I was in Slough

[Elite Pete]

Just had a thought, I pressure washed the condenser from inside the engine bay out and also the radiator but that was over 2 weeks ago, could it be water is in one of the switches and is causing a short. Are the switches on the right hand side of the rad looking from the front of the car?

TIA

[Matchless]

Just had a thought, I pressure washed the condenser from inside the engine bay out and also the radiator but that was over 2 weeks ago, could it be water is in one of the switches and is causing a short. Are the switches on the right hand side of the rad looking from the front of the car?

TIA

Yep.

[Kevin Wood]

Had a quick look at the wiring diagrams and there is a relay that drives the fans at slow speed when the air con is on. However, if they're both running at high speed my money's on one of the thermal switches on the radiator or there's an outside chance that it could be the pressure switch in the air con circuit.

Kevin

[TheBoy]

I'm fairly certain that the 'high speed' fans are connected to ign feed, low speed fans to permenent....

[Kevin Wood]

I'm fairly certain that the 'high speed' fans are connected to ign feed, low speed fans to permenent....

Could be. There were certainly two fused feeds to the fan circuit and both looked permanent from the quick glance I gave it last night. Certainly a single relay failure will cause them to run at low speed indefinately. for them both to run at high speed we're talking about multiple relay failures or a single switch, but only if the feed is permanently live. If it's not then back to the drawing board.

I didn't realise you were working remotely, Pete. Has she at least got it temporarily sorted?

Cheers,

Kevin

[Elite Pete]

I'm fairly certain that the 'high speed' fans are connected to ign feed, low speed fans to permenent....

Could be. There were certainly two fused feeds to the fan circuit and both looked permanent from the quick glance I gave it last night. Certainly a single relay failure will cause them to run at low speed indefinately. for them both to run at high speed we're talking about multiple relay failures or a single switch, but only if the feed is permanently live. If it's not then back to the drawing board.

I didn't realise you were working remotely, Pete. Has she at least got it temporarily sorted?

Cheers,

Kevin

Im back home now Kevin and will have a look tomorrow but I havent got a clue where im going with this. So am I right in thinking that with the fans running at full speed its not going to be a relay and more likely to be wiring

[Kevin Wood]

Hi Pete,

Let me have another look over the diagrams tonight and come up with a plan of attack. There was one set of relay contacts which would certainly cause them to run at slow speed in the event of failure. Both fans at high speed requires 2 relays to change over so unlikely unless a thermo switch is driving them - hence themo switch more likely in this case. If Theboy is correct and the high speed side is driven from an ignition switched feed that's even less likely.

Have a look tomorrow at what's running and what's not and I'll try and put together some things to try to narrow it down.

Kevin

[TheBoy]

it may be the feed to operate the high speed fan coils relies on ign 12v, rather than the direct power feed to relay contacts - would need to check.

EP - is it both fans, or just 1?