Issue #1: Furnace does not start.
- Check the power line if power comes to the furnace, check the On-Off switch
- Check the incoming voltage make sure is 120-128 volt range
- Check if 24 volt comes out of the main transformer and the control board receive 24 volt.
Issue #2: If the Vent motor (inducer fan) does not start.
- Check power goes to the vent motor, if receive 120 volt
- If power there, then put external power to the vent motor see if start
- If vent motor does not work, then the vent motor is out of order. Replace the vent motor.
- If vent motor turn on, you have faulty code of pressure switch. Replace the pressure switch.
- If the power comes to the vent motor is not 120 volt, so the vent motor is not start. Replace the control board.
Issue #3: Furnace is running but no heat is being produced.
- Check the filter, dirty filter must be replace ride away
- Check the high limit switches, just tripped then just need reset.
- Faulty high limit switch, need to be replace the bad switch
- Note the temporary solution will be jump the switch. It will be very dangerous if leave it for overnight or longer term, the high limit switch is there for a reason.
- If no new filter there, also for temporary time, run it without filter; however for longer time dirt goes to the furnace and to the house as well.
Issue #4: Furnace starts running and turns on but after a few second turns off again.
- Dirty flame sensor, clean the flame sensor
- If still do have same symptom or similar, replace the flame sensor
Issue #5: Furnace turns on, the vent motor starts running.
- If you hear a click the gas valve turns on, but furnace not turning on, the Igniter not turning on. The igniter has to replace
- If igniter not turning on, connect it to external power of 120 volt, if turns on, then control board or pressure switch needs to replace.
- Check the voltage goes to igniter if it is 120 volt, if not it is control board if 120 volt is there then pressure switch needs to replace
Issue #6: Furnace is turning on, run for a 10 min or less then turning off.
- See if the blower motor turns on, if not, then blower motor needs to replaces
- If the blower motor is turning on, but still after a while furnace turns off, increase the motor speed and double check the high limit switch.