Re: heat loss in part of mobile home
When you installed the new unit, did you also install new ductwork? The ductwork on trailers is often full of gaps and holes that allow most of your heating and cooling efforts to be lost and not distributed to the desired locations.
My girlfriend also lives in a "manufactured home" and has similar heating and cooling issues. It doesn't help that there is no return air system, I suspect yours is lacking the same. This reduces the efficiency. Here, installers put a register directly under the thermostat, giving the thermostat false temp readings in relation to the actual temp in the house. The fix for that was to block off that register which has been a great help. Other things that help is to run fans and ceiling fans to help circulate cool air. Warm air is fairly well trapped behind closed doors.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!