Bunk heaters

Mine did that when i had APU problems and couldn't keep the batteries charged. It would shut off abruptly and never enter the cool down mode.

You could lift the battery cover and see if the batteries are swelling, if they are it's time for new ones.

 

Is it an Espar or Webasto?

 

Yeah probably not. mine would tank right around the time the warranty expired, 250k maybe.

 

If it's an Espar, Airtronic or Webasco which are all pretty much the same it can be a few things. These units will shut down when voltage falls below a certain level. Also, these units are programmable and by default will only run for I think 8 hours and will shut off and you need to start it again. You can download the manual and program it to stay on until you shut it off.

The one thing these units will do also is shut off abruptly with no error codes. That is usually a bad fan.

These units also will only work below 5,000 feet altitude and unless you have a high altitude pump will shut off after a while.

 

In addition to what's been mentioned, make sure that you don't have any clothes or anything blocking the intake port of the unit, located under your bunk. I had a unit doing this once and when I moved clothes away from the intake it corrected the problem and the heater did in fact restart when it was supposed to.

 

These type heaters can be affected by a couple things;
Fuel filter restriction.
Atomizer clogged.
Igniter dirty.


https://www.youtube.com/watch?v=T-YHv3DTueY