Re: After run fan & Pump

[Wallace White <wallace@remdesign.com>]

Jack -

Frequently one of the transistors in the after-run relay fails after the
pump stalls; open up its case and you'll quickly see which one it is, if
it has blown. You can replace it with a Radio Shack TIP31 NPN transistor
for about a dollar.

That transistor only affects the pump, however, so that can't be the
answer to all your problems. The fan is run by switching on the first
stage fan relay. The only other thing that turns on the first stage fan
relay is the climate control head; it does so any time you've got the A/C
on. Does the fan come on when the A/C is on? There's your test for the fan
relay--and the fan's resistor pack, actually.

I believe you can also swap the 1st and 2nd stage fan relays for debugging
purposes. I remember them both having the number "214" on top. 

Good luck!

- Wallace
  '87 5kcstq 155k

Jack Gagnon wrote:
> 
> I have been trying to track down why the after run circuit is not
> functioning in my 87 5kcsq off and on for the past few months.  When I got
> the car a few months ago, the after run water pump was bypassed due to a
> cracked housing.  I replaced the pump and it still does not run.  The low
> speed fan does not come on either.  I have tried connecting the wires at the
> temperature sensor to get the fan and pump to run but nothing happens.  The
> next place to check is the relays but I do not know how to test them.  Does
> anyone know how to test the relay for proper functioning?  It could also be
> a wiring problem but I do not know the proper voltage/function of the wire
> pinouts either.
> 
> Any ideas?
> 
> Jack