Thermostate not accurate switches on and off but
I had the same problem, with a brand new unit. I wrote to the distributor, who said that I needed a new control board. They asked me a couple of questions about the unit (to figure out which control board I needed), and sent me a control board at no charge. (Your mileage may vary.) Installation took about 40 minutes with my 6yo helping me (20 minutes without the assistance), and fixed the problem.
FYI, the control board comes with the thermostat permanently attached -- I suspect that it was just the thermostat that needed replacing, but the entire control board goes with it as a single unit.
Final note: The instructions that we were provided for replacing the control board were incomplete in a couple of areas. Again, YMMV. You need to 'figure out' the information that isn't in the instructions in a couple of spots. Not rocket science, but not obvious if you're expecting the instructions to be well written and serve as an effective guide in completing the replacement.
RTO Comfort Zone...
on Dec 23, 2010