Rad Fan intermittant - killing the battery

[SJ]

----- Original Message ----- 
From: "Ben Swann" <benswann at comcast.net>

Thanks for responding.

Problem summary:
88 5k non-turbo
Battery goes dead because the radiator fan turns itself on intermittantly .
.with engine stone cold.


> Just a few thoughts:
>
> The wastegate heat shield wire could get accidently grounded causing the
> after-run circuitry to be enabled - low speed fan on.
**** I dont have turbo. Nix this as source of problem.

>
> The fad fan switch could be shorting out -2 - positions AFAIR and usually
> fails in the opposite way IME.
**** I unplugged the After-run thermoswitch(mounted on bracket on back end
of valve cover). Fan still runs, so its not this switch.
The other switch is the 3 prong switch located in the radiator. Manual calls
it the "Rad cool fan thermoswitches".
I just tested the voltages at this switch. Pin 3(BL/R wire) is a switched
power source. No 12 volts with no key in ignition. 12 volts with key in and
turned to ignition.
If this fan thermoswitch fails, the fan wont run with ignition key out
because there is no 12 volts available to activate either the 2nd stage
relay or the 3rd stage relay. So, this is not the likely source of the
problem.

>
> The fan relay - in this case 1 of 2 could be shorting open or wiring
causing
> effect of rad switch on enabling relay causing fan to switch on.
**** Yes, one or the other fan relays could short out - thats always
possible. But, once shorted out, the relay would stay shorted out. On the
other hand, I have never heard of normally open relay contacts shorting out
in an intermittant way. If there was some dirt between the contacts that
caused the short, the high current draw of the fan would burn out the
contacts or blow out the dirt.


> AC circuitry causes low speed fan mode with AC on Bi-level, Auto, or Def.
> when ignition on and temp set low.
**** This circuit only works with climate control in the A/C function AND
ignition switch on to provide power to the "after run control unit".
There is no power here with the ignition off.
The climate control is in "OFF" position and igition is off when the fan
runs intermittantly.

> Just a few possibilities and the wiring diagram will reveal the details
and
> test with VOM - you're already onto it.
**** Yeah, I'm working on it. But this is a weird problem. The fan only runs
when it wants to.

> Also, definately recommend fusing the fan - ground side.  Should be
details
> in archives.
****I got the fan fuse bracket from a junkyard. Will install this in next
couple of days.

Tomorrow, I will remove the three relays and take them apart to see if I can
find something odd inside.

I cant find these relays in the FA. Can someone guide me to the page where
these relays are listed? 88 5000k-nonturbo.

SJ