Many of us complain about the repetitious opening and closing. Stagnant air around the thermo sensor in the fan kicks the unit on at a prescribed heat level, which is fine; but then the resulting moving air kinda acts like "wind chill" on that sensor, and it cools and activates the switch that closes the fan, sometimes within seconds of it fully opening. The thermo subsequently warms again because the interior of the coach never had time to vent, and the vicious cycle repeats. It would probably be more optimal to either have a sensor with a wider on/off range or one placed less exposed to the full and direct air flow.
That said, take Gerald's advice and contact the company. I understand that they've changed ownership over the years and I guess don't forthcome with free parts out of warranty like they used to, but are still customer conscious, have encountered this complaint before, and likely have created a resolution. They should be able to help.
-Joel