I have a weekender 2 thermostat. The battery light is flashing constantly. I have replaced the batteries, but the light continues to flash. With the new batteries, the thermostat will turn on the furnace but will not bring it up to temperarture and quickly turns the furnace on. The card that came with the thermostat states that if the flashing continues, you are supposed to replace the batteries, I have done that to no avail. Please someone advise.

It could be a bad thermostat. Do you still have your old thermostat? If you do put it back on and see if that cures the problem.