RV Repair: Duotherm Roof A/C Problem, ceiling assembly, interior ceiling

Question
Help! I fried my RV! lol I recently bought a used 1996 26' Dutchmen travel trailer with a Duotherm roof A/C with wall mounted thermostat.  Well, I wanted to use the trailer in my yard for occasional housing for my daughter when she visits, so I hired an Electrician to wire in a 30 AMP RV outlet on my house. He is a friend of a friend that is currently still in school and is an Apprentice and unlicensed...but he seemed knowledgeable and eager to get the work.  OK, here's where it gets ugly! He wired in 2-phase 30 AMP instead of single-phase 30 AMP.  When we plugged in the camper we heard a popping noise and that was it! He realized his mistake, but too late! He rewired it to single phase and we plugged it back in. He checked all of the circuits in the RV's electrical panel and they are all OK. It fried a portable microwave(no big deal!), but the big problem is that the Duotherm Roof A/C & Heat doesn't work now.  He said that he can't test anything in the unit because it's "low-voltage" and he has no experience or equipment for that. I can hear the thermostat "clicking" so I don't think it's the thermostat. Absolutely nothing happens in any setting, heat or A/C. Do you have any idea of what probably blew out and do you think I could get a replacement circuitboard/switch/relay/motor/whatever and do the repair myself? Any good advice would be greatly appreciated! :-)Thanks, Dave

Answer
Dave, When 220 is put to a coach bad things happen. First thing I would do is to check the compressor and make sure it is still good. You can do this by running continuity. After that in order for me to know  just what this ac has is for me to know a model number. But you can also pull down the interior ceiling assembly plate and look and see if there is a square box up in there. This is the control for the T-Stat to ac. If yours has this then I would check to see that there is voltage there as well as low voltage in the small wires that connect to it. You should be able to find 12 volt coming out of that box. If there is no box in there get the model number and we can go from there. I assume that you already looked at the neutral wire in the breaker box as this is the one that got 110 power to when it shouldn't. Look under the outer cover also and there you should be able to check for voltage to the start capacitor and relays if there are any up there. This is just general things to do but with a model number I can help you better. Thanks, Bill