Re: After run fans & water pump

[Wallace White <wallace@remdesign.com>]

Hien Pham wrote:
> 
> Is there a thermostat for this fan ?

There's just the thermoswitch that Jack has already tried bypassing. The
thermoswitch closes at a certain temperature and is open below that.

Jack, it sounds like you've checked most of the obvious things. The fuel
pump relay doesn't have anything to do with this system (AFAIK). You
don't know if that after-run relay you substituted was in good working
condition, though, do you? It's common for these relays to blow the
transistor that runs the pump--but even if that happens, the fan should
still work, since the after-run relay merely triggers the 1st stage fan
relay.

One explanation would be if this transistor in the a.r. relay is dead
(take a look inside) and the 1st stage fan resistor is dead. If that
were the case, the 1st stage fan would never come on. You can check this
easily by seeing if the fan comes on when you put the climate control
head into an A/C mode, which turns on the 1st stage fan.

Other than that, you can always go through the Bentley and check the
wiring. Good luck!

- Wallace 
  '87 5kcstq 153k

> >I am not sure if the after run cooling system on my 87 5kcsq is working.  I
> >have not heard any fan, injector or radiator, come on after parking the car
> >since I got it about a month ago.  The turbo water pump is currently
> >bypassed and I would like to find out if it works at all. I suspect it is
> >bypassed because one of the pump fittings is cracked.  I have tried the
> >suggestions on Scott Mockry's page to no avail.  I crossed the temp sensor
> >wires to try and get something to run but all is quiet.  I swapped the
> >afterrun relay with another from a junk car, no fans or pump.  I tried
> >swapping the fuel pump relay, no fan or pump.  I even tried swapping a low
> >speed relay and still no pump.  The fuse is good and I do not know what to
> >try next.  Any ideas?
> >
> >Thanks
> >
> >Jack