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I don’t know your coach specifics. You checked the 120VAC breakers and I assume all other AC systems are working on shore and generator except for the A/C system? Since the call for heat from the thermostat is working OK you say, but no A/C fans or compressor action, possibly there is a common problem in the thermostat wiring or plenum control relays specifically related to the A/C unit. The thermostat must be getting +12vdc for the call for heat to work. Check to see if there is a connection strap between RH and RC terminals (if your thermo has them). It may only have one terminal marked R which would connect to the +12vdc supply......usually through a fuse. This should supply +12vdc to the A/C portion of the thermostat.
Usually the thermostat terminals are labelled B for ground; Y for A/C compressor control relay; and GL and GH for the A/C fan low and high speed relays. Typically these 120vac control relays are up in the ceiling A/C plenum (probably in a metal junction box). When you call for A/C fans or cooling the appropriate mini relay in the thermostat should close (you should hear it if you listen very carefully) and supply +12vdc to operate the appropriate 120vac ceiling control relay and that relay would then connect the 120vac through to the fan or compressor in the roof top A/C unit. Since neither compressor or fans work then maybe the common ground B terminal has a problem connection or the +12vdc RC (if provided as a separate terminal) is not providing +12vdc for the cooling portion of the thermostat.
You might also have a 120VAC connection problem somewhere at A/C breaker and ceiling plenum control relays. Attaching an old connection diagram that may help. Note that your coach may be wired differently though and take care on live 120VAC circuits if you access them.
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