York Gas Furnaces: TM9Y Re: Diagnostic Codes / Fault Codes These York gas furnaces have a control board inside the furnace blower compartment that will flash a diagnostic code that shows the operating status of the furnace. Diagnostic Codes: Slow Green Normal Operation - no...

York Gas Furnace: TM9Y Re: Flashing Code 1 Code 1 = Flame sensed with no call for heat. In a Code 1 situation, the furnace control board thinks that the gas valve is stuck on and the flame is still burning without a call for heat. Therefore, when a control board goes into a code 1, it will...

York Gas Furnace: TM9Y Re: Flashing Code 3 Code 3 = The normally open (PS1 or PS3) pressure switch contact did not close after the inducer was energized. ► This is a "Soft Lockout" which will automatically reset after 1 hour. ► There are 3 pressure switches on this furnace. PS1 (1st Stage...

York Gas Furnace: TM9Y Re: Flashing Code 4 Code 4 = Main limit switch has opened its normally closed contacts. The control will operate the supply air blower and inducer while the open limit condition exists. ► If the main limit switch opens five times within a single call for heat,...

York Gas Furnace: TM9Y Re: Flashing Code 5 Code 5 = Roll-out switch has opened its normally closed contacts or low voltage fuse blown. The control will operate the supply air blower and inducer while the open limit condition exists. ► The primary limit is wired in series with the roll-out...

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...

York Gas Furnace: TM9Y Re: Flashing Code 7 Code 7 = Failure to Sense Flame (3 Failed Ignition Attempts) Qty Possible Causes: 1 Dirty Flame Sensor Bad Glow Plug Clogged Burners No or Low Gas Pressure Bad Gas Valve Bad Ignition Control...

York Gas Furnace: TM9T/TM9Y Re: No Heat - Flashing Code 8 Code 8 = Flame was established but later lost - 5 times. ► This is a Soft-Lockout which will automatically reset after 1 hour. Qty Possible Causes: 4 Dirty Flame Sensor 1 Water in Inducer Clogged Burners...

York Gas Furnace: TM9Y Re: No Heat or Cool - Flashing Code 9 Code 9 = Indicates reversed line voltage polarity, reversed low voltage wiring, or Grounding problem Qty Possible Causes: 1 Loose Ground Missing Ground Reversed Line Voltage ("Hot" on white) ...