Thermo King apu has no heat

Peterbilt. Thermo king with airtronic diesel fired bunk heater.
APU has a heater core and coolent lines inside the engine compartment and the lines are staying hot. I am guessing that is just for cooling the apu engine.
The bunk heater is wired into the apu control panel
When set on heat the apu starts up and blows air just like the Ac is on with the ac blower but not cold air.
Sometimes then bunk heater blower comes on but does not fire up nor put out much air.
The bunk heater is wired into a fuse box to the HVAC fuse but it has no power to it at least when the truck is not running.
I tried putting power to the wire to the bunk heater but that did nothing.
All fuses are good.

I thought perhaps glow plug or clogged fuel screens.

 

The ac runs fine. It does not put out heat. Sometimes when set to heat the ac blower comes on and the apu starts up. Sometimes it just turns on the fan in the bunk heater on a low speed.

 

That is what I have. Mine no longer just comes on by it's self . also took up running ac even if I start the truck

 

I have never got it to run. Only thing it ever does if I select heat is sometimes the fan in the bunk heater will come on slow speed. Most times either nothing or the AC blower comes on.
It did come on high speed fan once and did not shut off even after I turned off . It shut off a few minutes later. No heat in any case. Does not ignite.
I read something about starting one of these. It said the key needs to be in the ACC position . Is this right ?