An 87 with factory air has a 3 speed fan, not a 2. What you are calling
high speed may well be medium speed.

High speed is only turned on by the radiator temp switch when high
radiator temps are sensed.
Medium speed is only turned on by the A/C system when the pressure in
the hose gets too high.
Low speed is controlled by 2 things, either the radiator temp switch
lower section or the A/C relay when the A/C is on.

There is a relay for high speed, another relay for medium speed, and the
low speed is powered directly.

If you remove the medium speed relay and the fan still runs at what you
think is high, you must be right. If not, then you are really hearing
medium speed. The high speed relay is hidden and hard to reach while the
medium speed relay is right there in the main relay panel where you can
pull it in 2 seconds. Page 97.102 of the Bentley shows the middle speed
relay, speed 2, is in position 5.

Mark

Tom Salicos wrote:
> I have the A/C running after a couple of summers w/o.  Subie yes, but the
> van has always done this.  The high fan speed comes on when it shouldn't be
> required (as far as I understand).
>
> Sunday it was parked for about two hours on an 85 deg. Day.  When I started
> it the high rad fan came on immediately  and stayed on for at least ten
> minutes as I drove home.  Came on and off a few times.  The temp guage
> didn't show the H20 temp even to half way to the LED.
>
> Turn the A/C off and the hi fan stops.
>
> Other times it has just come on at high speed, even though it was no way
> near hot.  Stays on for a minute then shuts off.
>
> W/O the A/C the high speed fan never has to operate due to high temps.
>
> So, what controls the high speed fan when the A/C is on?
>
> Thanks for any tips.
>
> Tom Salicos
> '87 Syncro Westy EG-33
>