I appreciate everyone's suggestions. I will begin troubleshooting the
problem this weekend.

Ryan

On Thu, Feb 21, 2019 at 3:47 PM Ed <email99@nc.rr.com> wrote:

> These combination fan switches / thermostat controls also suffered from
> current overload failure from the current draw of the ac compressor and
> the evaporator fan, especially if the electrical connectors were not
> secure or if they otherwise didn't make secure connections.  Placing a
> load reduction relay in the rear for the compressor clutch helped
> protect the switch.
>
> I found the rather large current draw of the ac evaporator fan caused my
> fan switch to fail.  Because of the cost, when I replaced the switch I
> added 40 amp load reduction relays in the rear on the evaporator housing
> and had the original switch to control the relays while the power to the
> fan was drawn from the distribution box in the engine compartment.  I
> added an inline circuit breaker to protect this circuit.  Making this
> change resulted in protection of the fan control switch from overload.
> The switch has now lasted 20 years without a problem.
>
> I was amazed the speeds of the fan were much higher because there was
> much less voltage drop in the shorter circuit from the distribution box
> than in the much longer circuit from the dash switch.  I found the low
> speed of the fan was now about the same as the old medium speed; the new
> medium was about the same as the old high; and the new high speed was
> way stronger than needed for a bus with both the original rear ac unit
> and an added dash mounted ac unit.  I rewired the speed reduction
> resistors to reduce all the fan speeds so the new high speed was about
> the same as the old high speed.
>
> If I had done this before I added the dash ac unit I would probably not
> have felt the need for adding in-dash cooling because the high speed fan
> would have given enough air circulation for cooling.  Note this is a '86
> Westy with the old style ac unit.
>