Dash AC intermittently blowing cold air, then hot

#1
Dash AC intermittently blowing cold air, then hot
My Dash AC blows cold air when the engine is cold, but after it gets warmed up it blows hot air. I assume that it has a Evans Tempcon Electronic Coolant Valve that can shut off the coolant to the heater core when the dash AC is turned on. There is also a Vacuum Pot on the bottom of the AC shroud which I think operates a flapper blending door between the heater core and the AC. With the engine cold and idling, I get cold air. But going down a flat highway engine not under load I get hot air. Pulled into a rest area and with engine warm, and at idle I still get hot air. Is it the Evans Coolant Valve that is bad, or something in the controls. I have heard that some replaced the valve with a manually operated ball valve to use during the summer months. Can anyone shed some light on this and is there a way to check it out.
Mel
 

C Nash

Senior Member
#2
Have you checked to see if the clutch on the compressor was still engaged when not cooling? Probab;y a door not operating right allowing the heater to out do the cooling. Let us know what you find. What RV do you have?
 
#3
It has to be a Vacuum Leak or kinked line because now it is blowing through the defrosters no mater what position the mode switch is in. That is a safety feature when Vacum is lost.
Mel
 
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