Tripac Apu wont charge with AC on, charges fine without AC

It is probably running correctly,just managing the loads on it.If you have a laptop with Windows,you can find the USB cord coming out of the APU panel and plug it in.A little program will come up for your APU,and show any codes,if there's a problem.

 

Tripacs normally switch between the alternator and the compressor. Most likely your compressor is running constantly.

Do you have the 120 amp alternator? Is it the one with the orange voltage regulator?

 

If you have the heavy duty alternator, the one with the orange voltage regulator, you can disconnect the load control circuit and run a jumper from the alternator ground to the negative post on the voltage regulator. That will make the alternator run whether the compressor is running or not. The load control circuit is a California thing and you don't need it.

Those two little cylinders on the back panel of the APU enclosure are resistors. One is two ohms and one is four ohms. Both lead down to the voltage regulator and come together at the negative post. When the four ohm circuit is active you get about a third of the alternator's max output. When the two ohm is active you get two thirds. When both are active you get the full charge. And when both are inactive the alternator isn't charging. Just disconnect them and run the jumper. Mine's been running that way for about a year now.

Use a heavy wire. Ten gauge at least.

 

20250327_145830 by Antinomian posted May 25, 2026 at 8:32 PM

You can see the model number and the two wires that need to be removed.