Gas Furnace - Blowing SSU Fuse / Tripping Breaker

York Gas Furnace: YP9C

Re: Blowing SSU Fuse / Tripping Breaker

The furnace either blows the SSU high voltage fuse or trips the breaker when power is applied.

CHECKOUT:

1. Check Inlet Power Wires

• Turn off power to the furnace at the breaker.
• Remove the fuse from the SSU switch.
  • Test resistance of the fuse with a multi-meter.
• Remove the SSU switch from the junction box.
• Check for any burnt wires or arc spots.
  • Repair wiring if necessary.
  • Be sure to apply electrical tape around the bare wiring connections.

2. Check Control Board

• Open necessary control panels to access the furnace control board.
• Inspect the control board and wiring for indications of burning or electrical arcing.

3. Check Blower Motor

• Remove the high voltage plug from the ECM motor.
• Look for signs of electrical arcing around the motor terminals.
• Leave the high voltage plug un-plugged from the motor.
• Leave the SSU turned off and re-apply power by turning the breaker back on.
• Turn the SSU switch back on.
  • Fuse Blows or Breaker Trips = Bad Control Board or Shorted High Voltage Wires
  • Fuse & Breaker OK = Bad Blower Motor or Bad Breaker --> Confirm with the following:
    • Turn off power to the furnace.
    • Re-attach the high voltage plug to motor.
    • Re-apply power to the furnace.
      • Fuse Blows or Breaker Trips = Bad Blower Motor