Originally Posted by twcallahan1
I had the same problem and the solution was to remove heater cover from outside of RV. Next to the fan is a black switch that is labeled off and reset. If it is in the off position the switch to reset. This should correct the problem. Apparently the heater fan is 12vdc and provides control voltage to the AC until thermometer. Once the switch is reset then the voltage is restored and the heater and AC should both work barring any additional problems.
Note you need to remove the 4 screws around the exhaust as there is a screw under the shroud that holds the panel onto the side of the RV, Six total screws on panel and four on heater exhaust shroud.
The OP's problem had nothing to do with the furnace, but welcome to the forum and thanks for trying to help.