This happened last week. The furnace itself was kicking on(which it always does for a half minute or so before blowing hot air) but wasn't blowing hot air. The thermostat on the wall read "replace batteries" so I did and after that the heater was working fine. I woke up this morning to find the temp inside was 64 and I had it set on 70. The furnace continues to click on but does not blow hot air. It just continues to click on and shut off. Help!
bad blower relay on control board / motor capicator/ bad motor. Will need vm to check. Have you checked to see if the blower motor will work on cooling speed ? Set thermostat to fan on. If blower starts blowing. Probably bad relay for at control board.
I took your post to mean that the blower wasn't comming on. If this isn't the issue disreguard my post
Besides checking flame sensor 'connection', try cleaning this sensor (by one of the burners; not the glow ignitor) with emery cloth, fine steel wool. Wear gloves. Search this forum to see pics of flame sensors.
Tell what point you are at:
1. Combustion fan/induction fan/ventor fan comes on
2. Air pressure switch closes
3. Ignitor glows
4. Gas valve opens, burners light
5. Blower motor starts
Note LED flashing on control board. Check decal on furnace door for what it means. If no detail, search internet for codes meaning.