Well, we got the relay board. Originally, I thought the board was bad in #1 AC as #2 & #3 were communicating and working, but #1 was dead. However, the relay board was bad in #3 AC unit. Once removed you could see the corrosion on the female communication terminal. Replaced the board, hooked up thermostat to the wall, and did a reset. All 3 units working now. Thought I'd pass it along to all.
2006 Travel Supreme Select