IF that extension cord is not loose and removable and is wired on one end to something, odds are the previous owner wired THAT cord for the rear AC so he could run the rear AC. You have a 30 amp RV. That means you cannot run BOTH AC units on 30 amp power. The Rear and Front AC switch is for when on 30 amp shore power you can select the front or rear to run on shore power. To run BOTH on Genset, you put the switch in Front AC and the genset will run both AC units
MAKE SURE THAT THAT EXTRA EXTENSION CORD IS NOT HOT ON THE MALE END WHEN THE GENSET IS RUNNING. I HAVE SEEN IDIOTS WIRE AN EXTRA CORD FOR THE REAR AC AND THEY WIRE IT DIRECT TO THE AC THRU THE GENST WIRING AND WHEN THE GENSET IS ON THAT END HAS 120 VOLTS. Doug
