odd heat issues

Most bunk heaters are programmed to only run for so many hours then shut off like the Espar and Airtronic. Instead of turning the heat up try turning it off then back on again.

These units can be programmed to turn off at 6, 8, 10, 12 hours or stay on all the time.

 

Been thinking and can't think of anything obvious other then the electric valve that controls the bunk heat.

 

If the heater hoses going into the bunk are hot, I'd check the door flapper for hot/cold. I don't think you have a valve that shuts coolant flow off. They are pressure sensitive and we've had a few that were sticky and would get hung up sometimes. If it's too hard to move the flap, it stops trying. I can't remember if it set a code or not though. I'm thinking that it did set a code, but not a driver warning, we had to hook up ESA to find the code.

 

Sometimes on some trucks if the engine is at idle it dosent flow enough water to the bunk system. Try bumping the idle up a couple of hundred RPM.