While on shore power -
1. Battery doesn't charge correctly even with a battery charger
2. Air conditioner won't run.
3. Refrigerator doesn't run correctly.
All of those suggest your 12V DC system is not functioning correctly. You need 12V DC for the thermostat and relays that operate the air conditioning, and the refrigerator needs 12V DC for its circuit boards and lights.
Check your tank monitors, where one of the indicators is for battery/12V DC voltage. When on shore power, it should read 4 lights. If down to 1 or 2 lights, that might explain the Air Conditioner and Refrigerator symptoms. And it's probably an indication that the Power Converter is not working. The battery may also need to be replaced. You can have it tested by taking it to many auto parts stores or Walmarts that have auto bays. Trailers need deep-cycle batteries, not the standard auto battery.
It's also worth rechecking the monitor with the battery disconnect switch OFF. If the battery has an internal problem that's affecting the converter output, the monitor panel will jump up to 4 lights with the battery disconnected.
The Power Converter is usually located behind the rear wall of the pass through basement storage. It it powered from a dedicated circuit breaker in your main panel, which goes to a dedicated outlet near the Converter. Locate the breaker and flip it OFF and back ON. Recheck the monitor to see if you now have 4 lights. If not, open the basement and check the 3 on-board blade-type fuses located on the Power Converter. If the battery was installed with reverse polarity, or if the charger was connected with reverse polarity, those fuses will blow.
If you need to replace the Power Converter, on most Bighorns, it's a
Progressive Dynamics PD9280. It's typically mounted with 4 screws that need a square #2 bit. The power connections are simple and require an allen wrench of the correct size - sorry, I don't remember the size. There's also a ground wire connection that I think is another square #2 screw. You may find the ground wire connection takes a lot of force to loosen. Just make sure you get the power and ground wires back the same way and there's no need for an electrician. The tough part of the job is usually just squeezing into a small space and loosening screws. Be careful to avoid dropping the screws. Before working on the wiring, unplug the Converter's power cord and over by the battery, turn the battery disconnect switch to OFF. That will both turn off the Converter, and the 12V DC on the wires.
You may find our owner-written user guides and troubleshooting guides helpful. There's an Electrical user guide in
this folder, and a 12V DC Block Diagram and Diagnostic guide in
this folder.