Fans......mind of their own ??

[S4CJO]

Not sure if anyone has had similar but thought I'd ask.
Occasionally even when the car had not been run, if I turn on the ignition to say open the boot then switch off the fans come on?
Switch back on and off the fans go off.

[s p a c e m a n]

Weird. Have they been modified in any way, do the fans continue to run with the ignition off when the engine is hot?

[S4CJO]

Yes, work fine when driving usually off unless in standing traffic then on until temp drops usually less than a minute.

[Penelope Stopit]

What fan control are you using

[Steve_D]

Not sure if this is true of all cars but the earth wire from the otter switch goes across the front of the engine and earths on the casing of the alternator. As there is no logical reason for a random black wire to be connected to the alternator it sometimes gets connected to the wrong place on the alternator when a change is made.

Steve

[Penelope Stopit]

Steve_D said:

Not sure if this is true of all cars but the earth wire from the otter switch goes across the front of the engine and earths on the casing of the alternator. As there is no logical reason for a random black wire to be connected to the alternator it sometimes gets connected to the wrong place on the alternator when a change is made.

Steve

If this was the case the fans wouldn't work as normal with engine running

[S4CJO]

Setup is std otter switch no additional overrides.

issue with the fan relay?

I'd be in the garage today to check but do renovation work on house i've put my back out, so will take your thoughts and look when i get chance.

[Penelope Stopit]

S4CJO said:

Setup is std otter switch no additional overrides.

issue with the fan relay?

I'd be in the garage today to check but do renovation work on house i've put my back out, so will take your thoughts and look when i get chance.

Yes the relay could be at fault. A more worrying scenario would be a short in the wiring harness

[Loubaruch]

I had a problem a while back and it was the Fan Relay. In my case the relay contacts were welded to the relay base through arcing and took a fair bit of careful sorting to avoid damaging the relay base in the fuse/relay unit.

Worth checking the Earthing as well. From memory the fans are earthed on the front cross piece.

Edited by Loubaruch on Sunday 9th July 22:29

[S4CJO]

Thanks all, comments gratefully accepted so will get checking once this bad back sorted.....

[WOO5IE]

Depending on the age I think the Latish ones had two relays , one for each fan. So unless it is just one fan only it could be the otter switch or has a previous owner wired in a fan override switch. I have one under the dash right next to the boot opening switch.