Lincoln,
I'll describe the simple way to do it without an override switch or an in
car pilot.
You'll need some 15 amp wire, an inline 10 or 15 amp metal or bakelite fuse
(don't use a plastic one, they melt if used for anything that draws more
than a radio), a Mini Bosch relay (or similar) and some connectors,
soldering gear or crimper etc. There are some do's and don'ts with wiring a
thermo fan, the main don't is run the amperage draw for the fan through the
Mears control (thermo switch) as they sh*t themselves at the worst possible
time like nearly always half way up some huge hill.
A Mini Bosch 30 amp relay has 4 pins
Pin 87 - connect a wire to positive terminal on the fan motor and connect
the Earth connector on the fan motor to Earth on car body.
Pin 86 - connect a wire to a terminal on the Mears control. Connect +12v
ignition feed (from active side of the ballast resister is good, it wont rob
your coil of any power as it's only a sense wire which will have a very
small power draw) to the other terminal on the Mears control.
Pin 85 - connect a wire to Earth
Pin 30 - connect wire to +12v active supply (usually from battery) with
inline 10 or 15 amp fuse fitted.
Adjust your Mears control. (Note. With Ignition ON, the fan will start if
you turn the temp adjuster right down as long as it's not freezing cold
outside)
Make sure you check that the fan turns the correct way to either suck or
blow depending if you mount it behind or in front of the radiator. You
change the flow by the way the fan mounts to it's motor, never reverse the
polarity on the motor (also very bad).
How it works.
With the engine on and warming up the Mears control breaks the +12v sensor
power from the Ignition feed to the relay. When the Mears control kicks in
at the preset temp it feeds power to Pin 86 which triggers the relay and
connects Pin 30 (battery power) to Pin 87 (to fan) and the fans kicks in.
It's pretty easy to wire this way, it's basic and not flash, but it's the
way most factory thermo fans are wired. This is not the only way to wire a
thermo fan, you can get flash and have a light on the dash that tells you
when the fan is on combined with a manual override switch in the car. The
wiring is completely different for this setup and naturally a heap more
complicated as it's all earth side controlled to avoid running live juice
all around the engine bay and through the firewall etc which is very bad. If
you want to do it this way give me a shout and I'll write it up for you.
Have fun with it, take your time and do it right first time.
regards
Terry
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Lincoln Yeo
Sent: Thursday, 22 February 2001 4:32
To: OZDAT Mailing list
Subject: Thermostat wiring - HELP!
Hey all, ive just installed a thermofan off an old EH onto my
1200 ute, and when the thermostat was pulled off, my mate didnt
take note as to how it is wired up again -
i know the relay with it switches the neutral, and the
thermostat only has 2 terminals - so can someone help me???
Linc
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