Guide - How to wire up thermofans

[CrUZida]

wrong wedding...

[Herus]

Dont worry, I just read what was written on page 4, which I had done a good job of missing so far.

Thanks guys,

Herus

[Cressid@]

+ reps for you all!

but i dont think you guys care.

wired all up and it works first go.

Now I dont have to top up water every times it cools down anymore! yay

[Cuzzo]

Hi,

Thread Dig,

Im going to wire two EL thermo fans using this diagram


But how will i wire the second fan without drawing excessive amperage through either of these two relays. ( i plan on using two relays only)
edit: Also the thermo switch i have is NC

[CrUZida]

To answer your question, you can't the way you've wired it up.

That first relay is pointless.

[Cuzzo]

Well i havent wired it that way currently.

Can you suggest or point to a diagram on how i should wire two thermos?

Use the second relay diagram twice?

[CrUZida]

Use the 2nd diagram twice.

The first relay there has no benefit, just do the 30 and 85 connections straight to two '87A enabled' relays directly.

[CrUZida]

Actually, I can see why you've done it that way.

Ditch the NC sensor and get a NO.

[Cuzzo]

OK i think i understand.....

Like this?

[Cuzzo]

Actually, I can see why you've done it that way.

Ditch the NC sensor and get a NO.

I dont really want to ditch the NC sensor.(just got it today at $50 )

[CrUZida]

If you want to keep the NC switch, then you'll need to wire that first relay in, otherwise your thermo's will run when you turn the key off, or run 3 relays.

You can get a 40A relay to replace the 2nd relay (and consequently the 3rd), but some don't recommend it.

[87lux]

edit i stuff up

[Cuzzo]

So umm i dont wanna use three relays cause that would be gay.

Can i get two relays in one thats weather proof?

[Sciflyer]

Hi

chaserbuddy.

You can always do what I used to do and use one of these to drive you thermo fan relay:
http://www.altronics.com.au/index.as...=item&id=S5595

I used to just bolt em on to the thermostat housing with an ally tab.
Good for a quick & cheep solution
Just make sure to get the 'Normally Open' type.

-A

I tried these and they work better than i thought they would (so far)

I used a N/O 80deg as above and just stuck it to the top of the radiator with a mix of superglue and heatsink compound

Setup is a 78deg thermostat, JAR alloy radiator and AU Falcon twin thermo fans



At the moment the fans are just wired in series (ie, half speed) through a single 30A relay and this seems to be fine for normal driving - they only come on if idling for a period of time (ie long set of traffic lights) and surprisingly the hysteresis isnt too great - on switch off the fans will run for maybe a minute or two which is good.

Will try wiring in an additional thermal breaker of a higher temp and relay which will switch the fans to full speed

+rep for this thread!

[RA35GT]

Measured the startup current and running current on the AU twin thermos in the Cressida today.

Startup: Peak current was like 75+amps (limit of this ammeter is 80A but only a very short time obviously), running current was around 19.2A. (This is the combined current draw, i.e. both fans which are currently connected in parallel)

Video of ammeter during startup and running here.
http://www.youtube.com/watch?v=9_0xgmAff0U

Ammeter set up as below. (Cressida is now wired with a single 60A relay, single 40A fuse and wiring sized for 50A). (The 40A fuse was what peewee used originally and has survived this long so I left it)


And a pic of the tridon thermo switch installed in the thermostat housing (As installed by peewee) Works very well and ends up quite neat.