Along with checking the start and run capacitors, and the motor starter device (PTCR), I would look at your controls (I am assuming that you have a direct blow unit with manual controls). Your problem could be in either the selector switch or the thermostat control. You should find a Dometic factory authorized repair facility, as your unit should be under warranty if it is less than 2 years old.
Lew Farber...RVIA Certified Master Tech...ABYC Certified Master Marine Electrician
SOLAR TECH ENERGY SYSTEMS, INC.
AM SOLAR ...MAGNUM…VICTRON ENERGY...LITHIUM & LIFELINE BATTERIES…MARINE REFRIGERATION