[Brad Townsend]

Ok so I guess it's on to the next challenge. I lost my dash heat last season. Might have to do with me pulling out the control board stretching the boden cable. The blowers work just no heat. I remember the previous owner telling me not to move the lever to far to the right otherwise I would be in for a ..... Wondering if somehow this could be cable related. 
Also noticed a micro switch on top of the controls that is activated by the temp slide knob. It has 3 wires, I checked for voltage and found voltage on the wire closest to the controller when the control knob was away from the switch in the cold position and no voltage on the wire on the opposite side in either position of the slide knob. I assume the mid wire is ground. Always wondered about the AC system which never worked and was told by Newell it's not worth fixing. Wouldn't it be something if the AC could be fixed with a new micro switch! Anyway more concerned about the heat for now.

[HoosierDaddy]

I think that micro switch runs the pump mounted in the engine compartment that pushed coolant from the engine to the heater coil in the front. On my 8V92 the pump is mounted on the frame rail on driver side of engine.

[77newell]

On my 93 coach that micros witch controls the boost pump noted in the previous post. However, whether it works or not will only determine the max amount of heat you can get up front. With the fans running if there is no heat at all, then you have at least one valve in the coolant flow circuit to the heater closed. The only valves I know of are the shutoff valves at the engine and the modulating valve up front controlled by the dash heat lever on the dashboard.

[Brad Townsend]

Just discovered my micro switch is bad. Will replace and hopefully all will be ok. Will report back later today.

[Brad Townsend]

Update: New micro switch did the job, I now have heat. $11 later.
Life is good!
There is 3 wires on the switch, I am wondering if it also has anything to do with the AC unit.
Ran it for a few minutes on AC but did not get cold.

[77newell]

Great. There is one valve I had forgotten about and if the microswitch isn't putting out power on request there will be no heat. On my 93 coach that switch turns on the pump at the same time it energizes a solenoid valve on the pump inlet.

[encantotom]

i do not believe the microswitch has anything to do with the ac. your vintage of coach has a dismal dash air con

tom

[Brad Townsend]

I am wondering what the weak link is on my vintage coach. Is there anyone with such a vintage that has a working AC system?

[encantotom]

that is an interesting question. i spent a ton of money on the system in my 90 (which is the same as yours) and at its best it was 1/3 as good as the one in my 02.

tom

[folivier]

Brad, part of the problem is yours is probably R12 if not converted. Expensive to convert to R134. A possibility is to use one of the propane/butane refrigerants. Google it, people have had success with these.