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Gas Furnace - Blowing SSU Fuse / Tripping Breaker

Article ID: 238
Last updated: 19 Apr, 2018

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.


Qty Possible Causes:
2 Bad Blower Motor
Bad Control Board
Shorted High Voltage Wires
Bad Breaker

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 
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Article ID: 238
Last updated: 19 Apr, 2018
Revision: 8
Access: Public
Views: 393
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