bunk heater

Does it blow warm air or only cold air? If it is only blowing cold, lift up the bottom bunk immediately after the heater stops working. Your bunk heater should be on the right side. There should be a green indicator light visible on the wiring harness. If the light is blinking, there is something wrong with the heater and the computer shut it down. If it is not blinking, then the heater should be functioning normally..... I don't remember what the heater control switch looks like in the volvo, so someone else will have to chime in and help ya with that.

 

Must have 1/4 tank of fuel mininum for it to blow hot.
That's the most common issue (that doesn't seem widely known)
But your issue sounds different, as in the case above, it will blow cold for
a minute or 2 then shut off.

 

I know this sounds stupid, but you are turning the temp control knob clockwise towards the hot side, right?

 

Make sure the intake is clear. Mine had a plastic bag in the way. It would over heat and shut off.

The wide bar on the controls in the sleeper keep hitting it until it comes to heat. Turn it on.