Sorry for the double post but I couldn't find a way to edit the first one or delete it.

Woke up nice and warm last night, upstairs ac had stopped working. Compressor outside is running, but no blower. Tried manually setting the fan from Auto to ON, nothing. Doesn't matter if I have it set to heat or AC. Using a Honeywell programmable thermostat, swapped the upstairs one with the downstairs one, no difference. (Checked the fuses at the main fuse box, all good.) I have a Lennox Value Series model 80UHG3-75A-3. I checked the voltage at what I believe is the transformer, its on the right in the attached picture, it read at 25v, also according the diag lights the circuit board reports everything is normal. So I assume the issue is the blower fan? I was able to spin it with no resistance. Anything else I can do to troubleshoot this?

Thanks,

You can test the motor by applying the correct voltage directly to the motor if you have the skill to do that. Naturally you have to disconnect the power wires feeding the motor to prevent feed back. It could also be the blower motor relay causing this problem. Since the motor is not trying to start the capacitor for the motor is probably not at fault.

You can test the motor by applying the correct voltage directly to the motor if you have the skill to do that. Naturally you have to disconnect the power wires feeding the motor to prevent feed back. It could also be the blower motor relay causing this problem. Since the motor is not trying to start the capacitor for the motor is probably not at fault.

Thanks, as an update I removed the control panel to find a large burn mark on the back, odd, since the diag lights are blinking a normal status, but I am guessing this is a bad thing and the board will need to be replaced.

It is possible that burn mark does mean the circuit board is shot. That is usually the case. Post a PIC if you can.

Burn marks on back side of control board almost always indicate fried board. Im betting a new board will solve the problem.