Our furnace is running, pumping warmish air. The thermostat is set at 68*, but our furnace doesn't seem to be able to heat our house over 61*. I've turned the thermostat and the furnace off and back on (the only troubleshooting I know!) with no results. It's a coleman evcon G FD024517A.

Watch to see if the flame is staying on, or if it goes out after a few seconds. Sounds like a dirty flame senser. You may be best off to have a pro into look at the system, as cleaning the flame senser on the colemans requires burner dissasembly.