Guide - How to wire up thermofans

[Grega]

very timely. wiring thermos on the ta22 at the moment.

as per cuzzo' last diagram ; if you want to run a NC thermoswitch and one SPDT or 'changeover' relay as they are called, you could substitute a switched ignition source to 85 on the relay with a constant fused source from battery....

not sure how the relay will like this ; over time i suspect your battery will go flat too ;

ps; these type relays are in VN Commodores as the lmp check relay (the metal one) OR Narva part number 68044 (resistor protected) or 68048 (diode)

[Hengsta]

Bumping this back up!

Anyone can do a diagram for me with one fan running on ignition switch and one running off a manual switch inside the car.

I got no idea how to do it.

Any help much appreciated.

Cheers, Heng

[RA35GT]

Bumping this back up!

Anyone can do a diagram for me with one fan running on ignition switch and one running off a manual switch inside the car.

I got no idea how to do it.

Any help much appreciated.

Cheers, Heng

Any reason you dont want to use a temp switch to switch them dood?

[ballpencil]

read the whole thread from the beginning and failed to find anyone mentioning the possibility of running NC thermoswitch with just 1 (one) relay..

this can be done depending on one problem which will be explained/asked later.

basically it's the same as Witzl's two-relay diagram, only you omit the first ignition switch relay like this:

this way the fan will still turn on when the you unplug the thermoswitch. however, as stated earlier, there is a problem. the relay will still be activated (pulling current) even with the engine cold and off (alternator not charging). i have to emphasize that it's only the relay activated. the fan will still turn off. as such, this diagram will work only if the current drawn by the 85-86 electromagnet coil is small enough to not be parasitic load on the battery.

mind that you're already drawing current from audio tape and ECU.

then the question would be, how much is the current drawn from 85-86 relay coil? i.e how long can you keep the engine turned off before you finally lose cranking voltage from the battery? there's even the possibility of running a serial resistor with the fuse as to reduce the current drawn by 85-86 coil.

[TheStitt]

Pee Wee was there any solution to the 2 fan 3 relay NC switch???

I'l

[88MKIII 1G-GTE]

Re:Ballpencil

Could you not use ignition power instead of battery?

[ballpencil]

Re:Ballpencil

Could you not use ignition power instead of battery?

If you're confident that your ignition wires will hold some 5-10 Amps of current flowing through for the fan, then do it. Personally i don't. I believe it's not designed to power such high requirements. You need to check you car's wiring diagram, fuse rating, wire thickness etc before you can decide to use ignition power. That's why i believe Witzl opted for the two-relay method.

[TheStitt]

As ball pencil said above. Ignition wires don't like massive loads

don't worry about me after thinking about Rudi's post. I'm happy running the set up I've got written out.

[CrUZida]

Pee Wee was there any solution to the 2 fan 3 relay NC switch???

If you use changeover relays then you can get away with 2 (one for each fan, both switched by the same NC switch).

But I'm not aware of a changeover relay that would be large enough to handle 2 fans.

[TheStitt]

Im just going to use a single relay to run the ignition into two relays 1 for each fan

[Bananaman]

I did mine recently.. Using 4 relays wasn't *that* bad, obviously just bridged across the ignition trigger, and the NC switch inputs.. Did it all to fit in a jaycar plastic box, but haven't finished tidying it up yet

I might as well add, i used a 92 on 87 off switch. On my 1J, this translates to exactly how i want it - if i'm driving along, there is enough air to cool the car without the fans. When i stop, they kick in. They work well enough that with the car sitting still, they will cycle on and off. Do have thicker alloy rad, not sure how much of a difference this makes.

[Viper]

Im just going to use a single relay to run the ignition into two relays 1 for each fan

This is what I did too.

1 relay to trigger Ign for another 2 relays.
These then power each fan, with the temp. sensor pulling them both to Gnd.
This way you could also potentially move to a dual stage temp sensor and only use 2 fans when required.

[egamirrorim]

I've just finished installing an alloy radiator with a themofan setup on my RA28, all the wiring is done for the thermofan except for one: I have a wire that needs to go to 'ignition', all of the wiring diagrams I've looked at DO NOT specify where exactly in the ignition circuit I should be connecting this to. I was going to just attach this wire to the positve on either my igntion coil or ballast resistor but my engine builder said these are both wrong. Do I have to attach this wire into the 'run' circuit on the back of the ignition key barrel?! I have an oil pressure gauge wire that needs to go to this as well, so I'm really not sure how I'm going to attach all this to such a small contact!

Please help - this is the last thing holding up my 10 month rebuild!

[ballpencil]

i don't see why you can't hook it to the coil ballast resistor positive.. it's not a huge load anyway, just a single relay basically, just around maybe 500mA.

[egamirrorim]

i don't see why you can't hook it to the coil ballast resistor positive.. it's not a huge load anyway, just a single relay basically, just around maybe 500mA.

My thoughts exactly.
My engine builder said I should not have any unnesessary loads (thermo fan draws 11 amps) attached to the startup circuit but the thermofan switch is an 85-90C item - I dont imagine the coolant will be anywhere near that hot at startup, even sitting in the baking sun, therefore the fans should not kick in and there should be no draw on the circuit except for the relay which is negliglble...