Hello Vicki & Ed,
I also have two 30A cables to my boat (one to the Air Conditioner and one for the house). This system was factory installed by Endeavour
using a rotary Onan manual transfer switch. I have had similar problems in the past ...... my recomendations (for what they are worth) are as follows:
1. After disconecting both power cables and the battery
cables to any inverters on board, bypass the manual transfer switch. You can do this removing both the black and white wires leading from the Air Conditoner breaker panel to the transfer swithch (remove them at the transfer switch) and reinstalling them on the same poles as(and along with) the white and black wires from the shore power to the transfer switch. by moving the white and black cables on the transfer switch (the black and white DO IT MIGHT BE A GOOD IDEA NOT TO START THE GENERATOR
WHILE IT IS WIRED THIS WAY! MAY NOT BE A GOOD IDEA TO TURN THE INVERTER
ON EITHER! After you have bypassed the transfer switch, reconnect the shore power cables try your air conditioner ....... If it works with no problems, then you probably have a bad transfer switch. REPLACE THE TRANSFER SWITCH! If you still have the same problem It's probably not the transfer switch however there is no guarentee that it's not the transfer switch along with some other problem.
2. If you still have the problem, you might try wiring
a power cable direct to the transfer switch (reinstalling them on the same poles as (and along with) the white and black wires from the shore power to the transfer switch). Now try the system again, If it works now, the problem is either in your boat's power inlet or the wires between your boat's power inlet and the transfer switch. If you still have the problem it's probably not the boats plug or the wire between the plug and the transfer switch. But again, there is no guarentee that it's not one part a larger problem!
3. If that doen't solve the problem just keep bypassing things (like the wires from the transfer switch to the Air Conditioner panel) ..... eventually, You'll find the problem.
is on the transfer switch itself or the power inlet!
If it turns out to be the boat's power inlet simply replace it ........ If it turns out to be a rotary type trasfer switch, you might consider replacing the rotary type with two blue seas AC power source selector breaker panels
(blue seas #8032). I did that on my boat and its works flawlessly. The rotary switches (at least the Onan type) are complicated and seem to go bad constantly (before changing over to the selector switches i replaced the rotary switch two or three times).... they are also expensive.
Good luck and I hope this is of some help