Fan Override

[Andi]

I would like the simplest way of fitting a fan override switch in my dash so I can switch the fan on

when i need to. I have a three post toggle switch, 25amp cable with inline fuse junction.

 

Thanks

[Big Jim]

The problem with override switches, is that it relies on the most unreliable piece of technology to operate it, ie. THE DRIVER!!

 

 

Do the job properly, get the required bits and wire it LIKE THIS

[geoff shep]

Unless of course he does actually mean an 'override' switch - to override an existing system. In which case you just need an alternative switched supply to the relay.

[Andi]

Unless of course he does actually mean an 'override' switch - to override an existing system. In which case you just need an alternative switched supply to the relay.

 

 

Yes Geoff,

Could I not run a live from the fan to the battery via the dash switch which would cut the fan on and off?

Electrickery.............. The devils own

[Guest robinj66]

If you already have a thermostatic switch in the system (and assuming no relay) then the easiest way is to connect a rocker switch across the thermo-switch. Downside is that you could be putting a lot of current through the rocker switch which may eventually burn out.

 

If you have a relay in the system, then do as suggested above.

 

Works OK for me but using a relay is the best way

[Andi]

If you already have a thermostatic switch in the system (and assuming no relay) then the easiest way is to connect a rocker switch across the thermo-switch. Downside is that you could be putting a lot of current through the rocker switch which may eventually burn out.

 

If you have a relay in the system, then do as suggested above.

 

Works OK for me but using a relay is the best way

 

 

Mmm

Think i`d better go from the relay when i suss what wire does what

Thanks all

[geoff shep]

It will depend on your current (ha ha ) system. Is it the sierra system and fuse/relay box?

 

My sierra manual shows direct wiring from battery to motor to switch for pre-'89 models and a relay for post '90 cars. Either way, the thermo switch is in the high current circuit. This is NOT the same set up as Jim's diagram, which would be obvious way to wire it if starting from scratch. The relay in the sierra setup (as shown in Haynes) acts to isolate the system with the ignition off. So, if you have the sierra setup, even with a relay, it's either a fat, high current, run through the switch OR you would need to add an additional relay, activated by a dash switch.

 

So first, find out what the existing setup does.