MCI Electric Water Valve Troubleshooting

[Doug1968]

Fellows,

I am trying to troubleshoot the electric water valve located in the front bay of my 102A3. The PO had removed the electric valve and replaced it with a manual valve. Trouble with this is there is no way to control the cabin heat?

I purchased a used valve and thought that I would check to make sure it operates prior to installing. I've attached the ground wire and the wire from the rheostat with no response. In checking further I found that there is no power coming through the wire. I checked the back of the rheostat for output and found that it has no power going to it? Both tests are with the main power on and the battery connected.

Does anyone know if the bus needs to be running to get power to this circuit? There is a relay in the electrical panel that is labeled Main Heat. It appear to be new? Could still be bad?

I have no information on either the water valve or the rheostat. I took the numbers off of each and tried finding info on the internet but no luck. Not sure if this is a 12v or 24v circuit?

Water Valve - RH 1663-1 Vapor
Rheostat - 16620239 Vapor Corp.

Any assistance someone might give me would be greatly appreciated. Possibly the engine needs to be running prior to this circuit being operable?

Also, if I close the water valve under the AC compressor will this keep the water from draining when I change to the new water valve?

Thanks,

Doug

[buswarrior]

Hello Doug.

In my MC8 manual, the coach heat/AC system will not be properly energized until the Penn Air Switch has sufficient air pressure applied to it.

In an MC8, the Penn Air Switch prevented the alternator from charging, the coach heat/AC from working, and showed the low air pressure light on the dash, until sufficient air pressure was reached.

You need both the maintenance and parts books for your coach!!! All the junction studs and wire numbers are there to make tracing the problem a breeze.

I would expect that the valve will be on the 24 volt side.

And, you need to close 2 water valves, the one you know under the AC compressor, and the other one is on the top of the engine, above the transmission, just before the pipes head up through the tunnel to the front, perhaps more easily reached through the access hole in the floor in front of where the washroom door is/was, or in the bottom of the back seat.

You'll most probably have to bleed air from the defroster core once you are done. There's a fitting at the top to do this. The heater core will be fine, as it doesn't trap air.

happy coaching!
buswarrior

[Tony LEE]

The valve is a normally OPEN valve so regardless of whether you need engine running and alternator fired up, if the coach is cold inside, the valve will be de-energised to allow water to flow through the heating coils. At the preset temperature the valve will be energised to stop the flow of water.