In cab switch for GU a/c thermo fans

[mudski]

Im thinking of utilising a spare switch on my dash to manully turn on the two A/C thermos to help cool the kettle when need be. I havent pulled out the wirning diagram yet. But would it be just a matter or finding the switch wire to the oem relay and bridging into this via the switch on the dash? Or would there be more to it?

Cheers.

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[the evil twin]

Pretty much exactly what I did, Cobber.

I spliced into the plug wot connects to the factory sensor at the bottom of the Rad.

The Factory Thermo Fan Relay is in with the other Relays next to the battery if you want to go that way but the Sensor wires were the easiest to get at IMHO... labelled A/C Fan or somesuch IIRC

It also means the A/C portion of the operation is unaffected

[lucus30]

I've thought about doing the same so I can keep em running with the ignition off while stopped on tracks for short stints

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[the evil twin]

I've thought about doing the same so I can keep em running with the ignition off while stopped on tracks for short stints

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Not much point as the coolant won't be circulating.

On that issue I never turn my engine off for 'short stints' if by that you mean 10 minutes or so and the engine temp is above average IE been working hard.
When you turn the engine off the temp of the engine components skyrocket as the dynamic transfer of heat from the hot mass of the engine to the cooler mass of the coolant effectively ceases.

[lucus30]

Not much point as the coolant won't be circulating.

On that issue I never turn my engine off for 'short stints' if by that you mean 10 minutes or so and the engine temp is above average IE been working hard.
When you turn the engine off the temp of the engine components skyrocket as the dynamic transfer of heat from the hot mass of the engine to the cooler mass of the coolant effectively ceases.
Yeah the problem is sometime I could walk up a hill climb and it be 30 mins and other times like 10. Depending on the amount of winching required to get cars up.

I don't like wasting 30 mins of petrol at a time

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[mudski]

Pretty much exactly what I did, Cobber.

I spliced into the plug wot connects to the factory sensor at the bottom of the Rad.

The Factory Thermo Fan Relay is in with the other Relays next to the battery if you want to go that way but the Sensor wires were the easiest to get at IMHO... labelled A/C Fan or somesuch IIRC

It also means the A/C portion of the operation is unaffected
Cheers...
Im not running the sensors in the rad. Being a zd to td conversion its using the ecu and chopped engine bay loom. I think i have to go via the factory relay.
So. I assume i just need to find the wire to the relay that is live when i turn the a/c on and just simply run the switch to this wire. And then from the switch ignition power...

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[the evil twin]

Cheers...
Im not running the sensors in the rad. Being a zd to td conversion its using the ecu and chopped engine bay loom. I think i have to go via the factory relay.
So. I assume i just need to find the wire to the relay that is live when i turn the a/c on and just simply run the switch to this wire. And then from the switch ignition power...

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Fair 'nuf... in that case, yeah, pick up the factory wire... or... put a changeover relay (87, 87a jobbie) inline with fan power.

[mudski]

Fair 'nuf... in that case, yeah, pick up the factory wire... or... put a changeover relay (87, 87a jobbie) inline with fan power.

I realised I had a spare relay to a switch on my dash that I no longer was using, its already wired in and the wire needed for the fan was there. I spliced into the fan loom. same spot where I spliced into when I added the second thermo. It worked, but it keeps blowing a 20A fuse. This fuse is on the +ive wire to the relay. To pin 30... Its not a c/o relay too. Does it need to be a c/o relay?
I'm assuming its blowing the fuse as the amps from the two fans are drawing are pretty high maybe? When it ( The relay )was being used to power some lights, it never blew a fuse once.

[the evil twin]

Two thermo fans will almost def pull more than 20 on start up, try a bigger rating on the fuse... and make sure you aren't feeding 12 volts back IE if your manually switching in 12 volts to the fans after the factory Fan relay it should be OK (but not best practice).

[mudski]

Two thermo fans will almost def pull more than 20 on start up, try a bigger rating on the fuse... and make sure you aren't feeding 12 volts back IE if your manually switching in 12 volts to the fans after the factory Fan relay it should be OK (but not best practice).

Thanks ill try a bigger fuse. As for the last bit. How do i check? Or where? I am using a relay after the factory fan relay.
What will happen when the a/c id turned on? Should i run a blocking diode, i think that's what its called, on the wire from the new relay?

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[jff45]

Mark, I would simply run the original power to the fans via 87a to 30 so you're getting your normal circuit with the A/C.
When you manually switch, the power would then go via 87 to 30 so you isolate the original relay and no need for diodes, etc.