Hi I have a 15 yr old carrier weathermaker gas forced air furnace model 58sxa080 the furnace works fine most of the time although every so often usually in the mourning and sometimes during the day ( after the thermostat sets itself back to 65 overnight) when the thermostat calls for the furnace to heat things up to 72, the furnace is in lockout mode. I tried cycling the thermostat down past the temp reading on the screen and then back up, but that does not help. What we have to do is go to the furnace, turn the power switch on and off 1-3 times to reset the circuit board then it goes through the start up procedure and everything is fine for days. Last year the heat exchanger was replaced under warranty ( except for a 400.00 labor tab)due to water leaking out of one of the cells I have checked the air intake and exhaust for blockages, cleaned the water trap, visually watched the spark igniter and pilot cycle ,replaced the filter . Any help would be greatly appreciated thanks GREG