Apu starts fine but no fan no heat and no air conditioning and no 120 volt.

NO MODEL APU told at all,
not a car at all is is a (HVAC BOX) add on. and POWER supply APU.
well it needs service, why not call maker for service manual and read the no start page.(trouble shooting )
did you do the 2000 hour service points yet???????
my guess glow plugs dead, in it.? cranks but will not start.

ComfortPro® diesel auxiliary power units (APUs) from Carrier Transicold are the trucking industry's all-around performance leaders. No other APU offers the combination of air conditioning, heating, cab power, engine warming, truck battery charging, optional shore power connectivity and a 2,000-hour maintenance service interval found in the ComfortPro diesel units.
some are
Tier 4 final 2 cylinder diesel engine.
air cleaner good, fuel good, battery power to it good.
glow plugs good, fuel filter good.

Have you tried rebooting the system? Just turn off the breaker for a few minutes.If you need more questions for your Air Conditioning Repair needs, check us out online.

What's the problem car running or not?

Maybe the compressor rotor is frozen (terminal) - that is why fuse blew.

Tripped breaker, no HIGH voltage.

If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

thermostat, heat sequencer, heat elements, fusible link no 240 volts. fan works on 120 volts.

do you have the lower door in place tight ?? because there is a door button switch. so if its not pushed in all the way you would have no power at furnace. also make sure nobody turned off the on off service switch usually above furnace or sometimes one at top of stairs and one down by the furnace .if those suggestions don't work you might want to turn each breaker off then back on incase one is tripped. if that don't work check for 120 volt at your fan timer board also it may have a automotive style fuse on the board which if blown it wont do anything. if there is 120 volt at board and the 24 volt circuit fuse is good its probably the fan timer board.

Are you getting 120 vac or 220 vac at the unit? Check the voltage at the first terminals inside the unit as well as the breaker. You should have 220 vac at the elements and you are dropping a leg some where.

be sure the fan setting on the stat is set for auto, not on. in this mode the fan should only run when there is a call for cool or heat.if the fan continues to run check at the control board to see if you are getting 24 volts low voltage between green and common. if you are then the stat is bad. if youaren't then your electric control board is possibly bad. a lot of gas furnaces fall into a failsafe mode when a sensor or function fails and the blowers stay on 24 7. you may well have several problems from what you are saying. if you turn everthing off and start a new cycle for heat the first thing that should fire up is the induced draft motor , then the ignotor, then the gas valve. you can check each item with a meter , generally 120 volts to the induced draft motor, then 120 volts to the ignitior, the 24 volts to the gas valve. then ignition and 120 volts to the motor. most furnaces have a heat terminal and a cool terminal on the board. common to heat should get 120 volts on a call for heat after the sequence of operationb has taken place. 120 volts should be sent to cool terminal on a call for cool. a continueous blower is a sign of a failed safety. perhaps the motor failed and the safety opened and the motor was replaced but the safety never reset?. look at all the little micro temp sensors around the burner. they are like little breakers and need to be pushed in to reset . usually like a little stem that pops out from a metal or plastic dic. some are size of a quarter, some the size of a dime.