Dodge Ram Truck Heater Not Working?

I have a 1998 Ford Ranger Truck that the Heater Module Switch went bad. A/C works fine but it doesn't do much good as a defroster. The 12 volt Defroster that are sold are about 12 Watts and don't do anything, don't waste your money.
What I did was buy a 400/800 Peak Watt Inverter, an extension cord and a 200 Watt Lashko Heater, total cost $60. I place the heater on the dash on a rubber mat so it doesn't slide and turn on the heat and use the blower on low to distribute the heat. It dried up the moisture and defrosted my windshield just fine.

My girl friend placed it on the floor boards and heated up the cab in no time. It was made to handle a office cubicle so a truck cab is no problem. There is no tip over switch on the heater so care must be used. It's only 200 Watts and the Inverter handled it with no problem. When I shut down, I shut off the Inverter so it doesn't drain my battery. Only problem it scrambles the AM radio signals but not FM, I can live with that when its C-O-L-D.