Another APU question

If you were just issued the truck, I would suggest asking the shop about it. If that’s not an option, drive it. Get a good full charge on the batteries, then recheck.

 

My Mack was tripping the low volt breaker under the bunk every time I started it last week. It shut down most of the sleeper lights and all of the 12v outlets, but my APU would start, run and charge the batteries. There is probably a fuse or a bad relay. They replaced the breaker and mine hasn't had an issue since. If it's a normal APU like a Thermo King tripac or Carrier, it shouldn't be connected to anything but the inverter and the batteries, and a wire to the ignition so it knows to shut down when you start your truck.

 

I've been running my own truck with an APU now for the last 8 years. Done all the repairs myself when the warranty ran out. The APU is a completely separate unit from the tractor, except for the truck engines coolant, also fuel from the trucks fuel tanks which runs through both the APU and to Truck engine. Without the coolant and fuel from from the truck engine it will shut down the APU within a few minutes. The APU should charge the truck batteries, provide power to the Inverter, also has it's own ac unit completely separate from the trucks ac. Also if a bunk heater was installed with the APU it is also separate from the trucks heater. When the batteries on the truck get too loe to start. Just fire up the APU & presto the batteries with charge right up. Yeah! Saved me countless numbers of times. It's a beautiful thing.

 

Hi. I don't have a reply to your comment other than to say, Good job! But you seem knowledgeable, so I'm asking for advice. I have a Thermo King Tripac APU. The inverter stopped working, off & on. The APU quits, on occasion. I jiggled the wires under the APU, and it started back, but for 3 hours or so. Not sure if it is bad wiring, bad inverter, APU issue...

Suggestions?? TIA