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TM9Y - Flashing Code 6

Article ID: 695
Last updated: 19 Feb, 2024

York Gas Furnace: TM9Y

Re: Flashing Code 6

Code 6 = Pressure switch opened (Code 3) 4 times during a run cycle.

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

► There are 3 pressure switches on this furnace. PS1 (1st Stage Switch usually .90") and PS3 (Condensate Switch usually .20") are wired in series to the pressure switch input.

The PS2 (2nd Stage Switch) wires in separately and will cause a Code 13.


Qty Possible Causes:
Bad Inducer Motor
Water in Vent
7 Water in Inducer/Clogged Drain
Improper Condensate Drainage
Bad .90 Pressure Switch
3 Bad .20 Pressure Switch
Water in Pressure Switch / Tubing


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.
  • 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 Switches

  • PS1 (1st Stage Switch)
  • Check for 24VAC between "C" on the terminal block and the Blk/Org wire on PS1.
  • Check for 24VAC between "C" on the terminal block and the Wht wire on PS1.
    • Power On Both Sides = Switch Closed ⇒ Check PS3 Switch
    • Power on One Side Only = Switch Open ⇒ Check PS1 Pressure
  • PS3 (Condensate Switch)
  • Check for 24VAC between "C" on the terminal block and the Wht wire on PS3.
  • Check for 24VAC between "C" on the terminal block and the Red/Grn wire on PS3.
    • Power On Both Sides = Switch Closed
    • Power on One Side Only = Switch Open ⇒ Check PS3 Pressure
  • Check PS1 Pressure
    • Use a pressure meter to check the pressure at the PS1 switch.
      • Watch for water in the pressure switch hoses.
    • Compare actual pressure to pressure rating on the switch.
      • Pressure near or below rating = Blocked or Restricted Vent
      • Pressure well above rating + Open Switch = Bad Switch or Water in Switch
        • Water in Switch is usually caused by a mis-run pressure switch hose.
  • Check PS3 Pressure
  • Use a pressure meter to check the pressure at the PS3 switch.
  • Compare actual pressure to pressure rating on the switch.
    • Pressure near or below rating = Blocked Drain
    • Pressure well above rating + Open Switch = Bad Switch

3. Check Condensate Drainage

  • Check the Robber Drain Coupling on the inducer outlet.
    • On horizontal runs, make sure the drain outlets are pointed slightly down-hill.
    • Remove drain hoses.
      • Water running out of coupling = Clogged Drainage
    • Make sure there is nothing inside the drain coupling clogging the drain outlet.
  • Check the drain hoses from the collector box.
    • Make sure all drain hoses are clear and have a downward slope.
    • ► Make sure the drain outlets are not clogged.
  • ! Make sure there is an "Air-Gap" in the PVC drain immediately upon exiting the furnace !
    • Any trap after the collector box before an air gap will cause drainage issues.
  • In extreme cold conditions, be cautious of Frozen Drains.
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Article ID: 695
Last updated: 19 Feb, 2024
Revision: 7
Access: Public
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