Working on propane and not AC tells me that you have not lost the charge and the cooling circuit still works fine. First you have to verify that you have 120 at the frige, open the back panel and check where its plugged up. If you have 120 there, move on to the back of the unit. There is a black plastic cover there, remove it and check all the fuses under it. If you have 120, and good fuses, my next bet would be the electric heating elements located at the bottom of the stack. Should have two yellow wires coming out; follow them back to the control board and ohm them out to check for resistance. If its none of the above, take it to an expert.
Good luck
Dave