I'm not much of a mechanic, so forgive me. Two summers ago, my AC stopped cooling. Fan still runs. Did bother to get it fixed. We had our first major cold snap here in Texas last week and the heater decided to stop heating. There is some warmth coming through, but not what it was before the cold snap (down-right HOT!!!). I read somewhere that if the thermostat is gone, my gas mileage will drop. I have noticed a drop in gas mileage. Use to get about 300 miles per tank. Now only about 230. Any thoughts? Many thanks.