Issue #1: Furnace does not start.

  1. Check the power line if power comes to the furnace, check the On-Off switch
  2. Check the incoming voltage make sure is 120-128 volt range
  3. 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.

  1. Check power goes to the vent motor, if receive 120 volt
  2. If power there, then put external power to the vent motor see if start
  3. If vent motor does not work, then the vent motor is out of order. Replace the vent motor.
  4. If vent motor turn on, you have faulty code of pressure switch. Replace the pressure switch.
  5. 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.

  1. Check the filter, dirty filter must be replace ride away
  2. Check the high limit switches, just tripped then just need reset.
  3. Faulty high limit switch, need to be replace the bad switch
  4. 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.
  5. 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.

  1. Dirty flame sensor, clean the flame sensor
  2. If still do have same symptom or similar, replace the flame sensor

Issue #5: Furnace turns on, the vent motor starts running.

  1. 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
  2. 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.
  3. 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.

  1. See if the blower motor turns on, if not, then blower motor needs to replaces
  2. 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.
Categories: Heating

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