In the great timing department, yesterday was the coldest day of the year thus far and it seems my heater is now having some issue. I have a 2011 FFH. When the engine is running, the heater works just fine, but when the engine switches off and the car is running in EV mode, the air blows cold. Not TOO big a problem while driving on the highway, obviously, but when sitting at lights or in a parking lot waiting on someone, it gets a bit chilly.

Anyone know what the problem is and if it's an easy fix, or should I just expect a large repair bill and take it to the local dealership for repair?

 

The only source of heat is the engine. IIRC, if you engage dual-mode upper defrost and floor settings, it will force the engine to run.

Confirm that your engine coolant level is correct.