Guide - How to wire up thermofans

[Cressid@]

hi, I am in the process of wiring up ford AU thermo fans on my cressida.
I have aircon working. If you could kinda draw a diagram to help me wire it up thanks?
I was going to copy the above diagrams. But I have 3 of them from previous pages and I dont know which one is correct to use for my application.

edited: what is HP switch?
I have got a temp switch Normally Open/

cheers

[RA35GT]

If you have a Normally open temp switch than any of the diagrams I posted up within the last few days, should work for you. (Latest diagram 101_7330r.jpg)

The only difference is how its wired into the ac system. (PS the HP switch is part of the AC system. its used to turn the condensor fans on factory systems when the a/c was becoming less efficient). You do not need to wire the HP as its not essential, but it would make the a/c work better in some cases.

[CrUZida]

HP switch is High Pressure switch (part of the aircon circuit)

Use the last diagram.

[Cressid@]

OH! Understood thanks.

[PlacentaJuan]

finished the wiring last night, and it works perfectly.

the hardest part was finding (and identifieing) the A/C LP switch. (which is just behind the RHS front strut tower down near the crossmember on mx83)

there is zero visibility on me mx83 and had to do it by feel, and its right next to the DUAL PRESSURE switch also.

after a few hours of mucking around i foudn that to confirm you have the right switch, when the DUAL PRESSURE switch is unplugged, the a/c magnetic clutch will NOT turn on (you can hear it quite clearly with the engine off and key in ACC mode)

the HP switch is only responsible for turning fans on/off, so if you have removed all your fans during the engine converion (like i did) then it wont do anything, and unplugging it then turning the a/c will have no effect on the mag clutch.

once i foudn the right switch i traced the wires back to behind the washer fluid bottle (for easy access) and spliced in a wire to hok it up in parallel with the THERMO SWITCH, and both of them switch to ground.

so now i dont have my twin fans running full time (it only takes 30second to cool the engine down to <90 at idle so it was a major waste of power and fan life) and the aircon has acess to the fans when required also.

btw now i notice how loud the fuel pump is!
thanks guuys for your help.

[takai]

Oh yeah, just FYI.
I know that Cruz has got away with running a pair of fans off a 40A relay, but if you are going to run the AU falchoon fans, then definately use two 30A relays.
Ive monitored a constant 21A draw from the fans, which is pretty damn excessive, but they do shift a lot of air.
I initially had mine running off a single 40A relay, which fried quite nicely. Now runs off 2x30A relays.

Also highly recommended is having neat wiring and relay locations like this:

Makes a world of difference when you are trying to find a fault.

[CrUZida]

Fair enough Takai, I was told they pulled 15A each, which is why I went for the 40A relay.

[The Witzl]

i would be using fully insulated female spades on your fused distribution block there chris.
You know you are going to short them out one day soon!

Re. using a 40A relay - if the relay still uses 1/4" spade terminals, then its realistically limited to 20A current anyway - above that and the temp rise at the terminal becomes quite high and you get excessive terminal resistance.
Also - remember that electric motors can draw SEVERAL times their normal current draw on startup and when under load. So i fyou were close to a relay's current limit, this would burn it out pretty quickly.

[CrUZida]

It was a Jaycar relay and harness...

[takai]

i would be using fully insulated female spades on your fused distribution block there chris.
You know you are going to short them out one day soon!

Re. using a 40A relay - if the relay still uses 1/4" spade terminals, then its realistically limited to 20A current anyway - above that and the temp rise at the terminal becomes quite high and you get excessive terminal resistance.
Also - remember that electric motors can draw SEVERAL times their normal current draw on startup and when under load. So i fyou were close to a relay's current limit, this would burn it out pretty quickly.

They have heatshrink over them now. That photo was taken quite early on.

[The Witzl]

It was a Jaycar relay and harness...

those are 30A continuous rated, and 40A burst.
just buy another one

[CrUZida]

Not my car anymore

[RA35GT]

LOL.

Will fix

[CrUZida]

Its been running for almost a year, including lots of hot summer days where it would have gotten a serious workout.
I'd be happy leaving it if it was still my car (would probably be worth buying a spare incase it stuck shut)

[RA35GT]

Yeah I'll just do that, get a spare and fix it when/if it breaks.