P1XU - Flashing Code 6

York Gas Furnace: P1XU

Re: Flashing Code 6

The P1XUD gas furnace has a 2-stage gas valve and 2-speed inducer fan motor. There are two, dual-port pressure switches which monitor both low and high speed operation of the inducer motor.

The low pressure port of the switches goes to the inducer motor and the high pressure goes to the burner compartment.

Code 6 = Pressure switch opened 4 times during a run cycle.

► This is a "Soft Lockout" which will automatically reset after 1 hour.

CHECKOUT:

1. Check Inducer Motor Operation

• Start the furnace with a call for heat from the thermostat.
• Observe and listen to the inducer motor operation.
  • Inducer motor starts → Step 2. Check Pressure Switch
  • Inducer motor hums but does not start:
    • Bad Inducer Motor or Capacitor
    • Item in Inducer (Remove inducer & check)
  • Sound of water "slurshing" = Water in Inducer --> Remove Inducer, pour out water, re-install inducer --> Step 3. Check Condensate Drainage
• Listen for sounds of water in vent piping.
  • If water is gurgling in vent, look for low spots that will hold water.
    • Pipe must have constant slope back toward furnace.

2. Check Pressure Switch

• Use a pressure meter to check the pressure at the switch.
  • Watch for water in the pressure switch hoses.
  • On a two-hose switch, be sure to check both sides at the same time (differential pressure)
• Compare actual pressure to pressure rating on the switch.
  • Pressure near or below rating = Blocked or Restricted Vent / Intake
    • Try removing the burner box cover & re-checking.
      • Drastic improvement = Restricted Intake
      • Little or no improvement = Restricted Vent
  • Pressure well above rating, switch should be closed.
    • Switch does not close = Bad Switch or Water in Switch
      • Water in Switch is usually caused by a mis-run pressure switch hose.

3. Check Condensate Drainage

• Check the drain coupling on the inducer outlet.
  • On horizontal runs, make sure the drains outlets are pointed slightly down-hill.
  • Remove drain hoses.
    • Water running out of coupling = Clogged Drainage
• Check drain hoses from inducer and collector box.
  • Make sure all drain hoses are clear and have a downward slope.
• ! Make sure there is an "Air-Gap" in the PVC drain immediately upon exiting the furnace !
  • Any trap after the collector box before the air gap will cause drainage issues.