TriPac Apu

The apu won't shut off until the battery voltage is greater than 13.56v for 15 minutes. Has it reached that point?

TA

 

Check the batteries....may need to replace old ones that may be unable to be fully charged.

 

Is it an evolution?

The setting for the shut off may be set too high.

Like above, it may be 1 or more bad batteries.

 

What's the outside temperature?

Mine doesn't shut down when colder than -10F. The coolant doesn't get warm enough to shut down.

Don't worry about overcharging. The regulator in the alternator will handle that.

 

There can be two reasons for it.
-Faulty temp signal
-Faulty voltage

In the return coolant line close to the APU, you should find a tube style double T with a sensor in each port.
One of them is the cold temp sensor. It failed on mine and the APU went crazy. Restarting right away after shutting down. Unfortunately, I don't know how to check on them.

For the battery signal, you need to remove the cover of the black box under your bunk. All the ports are marked. Search for the port marked with 'SEN'. Check if it's loose. If you have voltmeter, check and compare the voltage to your inverter. The wire might have a bad contact on the other end.
The SEN port is the first one in the corner. I can't tell which corner, since I don't know which way your unit is installed in the truck.

Good luck.

 

With the current set up the Tripac should be keeping water temp adjusted for two things, engine and bunk heater. In the winter the values to the cooling system should be open, in the summer, the valves may be closed. Remember a small APU is trying to maintain hot water in a enclosed system according to design specs. The only other reason the unit fails to auto shut down could be faulty system controllers ie, sensors and or the PLC.

I would rather have a APU running than a 14 liter diesel engine! At some point you need to take it in for PM scheduled Sevice and they can isolate and repair the faulty unit if needed.

 

Mine isn't set up that way. The system is not looped when either of the valves are closed. The hoses go straight out to the main motor and straight back. Closing a valve would completely stop circulation of coolant in the APU.

I'd have to add an additional hose between the inlet and outlet plus another valve.

I second the motion to check the voltage at the sense terminal in the control box. It could be wildly different than what the inverter is seeing.