Heater and A/C Dash Controls Not Working

I had a problem like yours where the dash heater/Air conditioner would work at times and then they would not. I brought it up to a friend of mine who is a mechanic and he said to check the ground wires. So on my diesel pusher all the fuses and ground wires are located in one compartment which makes it easy, so I started pulling on every white wire I could grab. Then I pulled on a wire that looked good on its connection, but as soon as I pulled on it, it slipped right out of the connector. I took the eye connector off and replaced it with a new one, and everything worked.

So you probably have a lose connection some where. If it started working while you were checking the battery compartment, it must be in there.