Prostar climate control issues

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What if there is heat coming from tube outside but not in bunk.

 

Here I go bumping an ancient post but, I'm bored so what the hell.

That tube that looks like a drain pipe is actually an exhaust. If you have hot air at the exhaust but no heat inside you probably have a problem with either the heat exchanger or the blender door in the bunk. I'll explain...
The ProStar bunk heater which is a product made by Bergstrom is a hydraulic heater. It burns diesel fuel to heat the coolant that is circulated through the same heater core that your truck uses while it's running.
If the heat exchanger is not working properly then it will not be passing that heat to the coolant - but this is unlikely.
It is also possible that the circulation pump that makes the coolant flow could be bad in which case the coolant could be getting heated, but it's not going through the heater core to deliver the heat to the inside of the truck.
The last option that I'm aware of is it the blender door, found underneath of the bunk, is not being actuated by the motor.
On prostars this is a cheap part that is prone to failure. On mine I used to hear a constant rattling noise until finally it wouldn't work. So I ordered the part for $15 and replaced it - problem solved.
A way to test for the problem being the blender door is to see if your bunks air conditioning will put out oh, and to see if the heater works when the truck is running. That is to say if you're getting hot air from the vents in the back of the truck. If you're getting hot air when the engine is running, it won't be the blender door.

 

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