P-30 Dash Air Conditioner and "H" valve
Originally Posted by padillab
I have a 2005 LY gas MH, 30 ft w/ slide and have noticed that the temp control knob on the dash does not really adjust the temperature up or down, but only turns the flow of radiator fluid to the heater core either on or off. There is no in between. Once the knob is turned up past a certain point, the temperature of the air that comes out into the cabin is just plain hot. I called AS and they said "yep, that's the way they made it." I'm not very happy with that
, but, does anyone know of a way to modify this system so that the heat temperature is truly adjustable?
While reading the archives I came across this post:
Any body with a P-30 chassis having problems getting the dash Air Conditioner to cool way down?
I noticed that my AC would be very cold at engine startup (about 58 degrees). But when the engine got up to temp (around 210 degrees) the air coming from the dash air was getting warmer, (about 70-80 degrees).
So the first thing I checked was the refrigerant pressures and they were perfect.
Then I checked vacuum lines to the heater control valve.
My system controls warm air with an in line water control valve that is vacuum operated. There is a second valve inside of the heater box that is mechanically operated with bowden wire and linkage. Both valves were working properly.
I got out my P-30 manual and it speaks specifically to a known problem with this setup.
The valve is not very proficient and allows hot water to enter the heater core on a constant basis. The heater core is placed directly adjacent to the AC evaporator.
Since the two devices are in very close proximity, the hot water that is in the core is raising the temperature in the evaporator and consequently effecting the temp of the refrigerant.
The corrective action is purchase an "H" valve from ACME heating and Air onditioning Inc. This valve is placed in line with the supply and return hoses the heater core. The valve is also bridged between the supply and return hose. This valve allows you to block all water from entering the heater core and re-route the water through the rest of the system.
This valve also allows you to better adjust the temperature to the heater. Cost is about 40 dollars.
You can search ACME Heatinig and Air Conditoner and read about the H valve.
Your problem is controlling heat and Ken solves it for a/c and heat.