Hi, I have a Concord Gas Furnace with Carrier Central A/C. Today I found out that the blower is not starting whenever A/C kicks in. It doesn't auto start for heat either. Tried setting Fan in Always ON mode and still doesn't start. However if I turn off Heat/Cool and leave the Fan in Always ON mode and turn the power to the furnace off and back on, blower starts. While in this mode, if I turn on Cool or Heat, the fan turns off after a minute or two and never turns on again unless I repeat the procedure mentioned earlier. Thought it might be the Thermostat and replaced it. Problem didn't go away. The PC board on the furnace reads "Honeywell Smart Valve II Ignition System". It uses four wires for the Thermostat. Any help will be greatly appreciated.

Thanks,
-SC

Sounds like your unit is controlled by a circuit board in the furnace area. These can be expensive parts and before you replace I would have a on site service call to determine exactly what part is defective. It could also be the thermostat depending upon what model number you have since some of them can be set up for delay activation and many other options.

Yes, it does have Circuit board to which the wires from the thermostat get terminated and also the wires from blower and such. I attached a picture of the furnace which I copied from the Concord brochure. Is there anything I can do before requesting a service call?
3876

At this point in time I am going to take a guess that it is the board. They do fail quite often but are not cheap. It is your decission as to what to do next.