furnace not working normal, Help!

[denny]

Few days ago, we have power outage in our area. After the power comes back, seems we have issue with the thermostat (model T8600c) or furnace. We setup the temperature at 22C, however even the room temperature is 18C, the thermostat seems does not want to work. I try manually to raise to 30C, no luck. One interesting thing is I follow the installer test procedure, when I release the WAKE key, it shows 6304 which does not match description on the manual. 6 - means 6 cycle per hour; 3-???(does not match any description); 0 - means heat/cool, system switch is OFF or auto; 4 - means heat/cool, manual changeover thermostat. And I have to manually disconnect the power to furnace, then power on it again. The thermostat will work normal for around 12 hours then becomes unusual again. And another problem is sometimes I am not able to force the fan on. I mean even I set fan to "on", no response. Any ideas? Should I go for any protection plan? If so, can you suggest one? I have to solve this problem ASAP cause I have a new born at home. Really appreciate any input and thanks for your time.

[HayZee518]

there may have been a spike in your system when the power came back on which could have "fried" a transistor in the thermostat. think of it as a power surge that electronic components don't like. try a standard thermostat instead of a programmable "stat"

[denny]

there may have been a spike in your system when the power came back on which could have "fried" a transistor in the thermostat. think of it as a power surge that electronic components don't like. try a standard thermostat instead of a programmable "stat"

seems it is not caused by thermostat. I replace the old with RTH7500. still no luck.
Thanks.