9 red flashes Polarity reversed or bad ground

What the control is telling you

The board sees reversed 115 V polarity, a poor ground, or swapped transformer leads. Heating and cooling are both affected and ignition will not start.

Applies to: York/JCI residential gas furnaces: York UTEC IFC furnaces, York White-Rodgers IFC furnaces, York TM9V

Likely causes

• Hot and neutral swapped
• Missing or poor ground
• Transformer secondary leads reversed
• Flame probe shorted to chassis

Test and repair steps

1. Warning: Verify with a meter before touching wiring.
2. Check polarity at the furnace and at the panel.
3. Check furnace ground continuity.
4. Check transformer lead positions.
5. Make sure the flame sensor is not touching the chassis.

Settings for these units

Clearance to combustibles · York TM9V

Leave about 24 in. at the front and 18 in. at the side for service.

Approved for alcove and attic installs.

Filter size by return location · York TM9V

Sizes assume high velocity filters (600 FPM); throwaway filters must stay at or below 300 FPM.

Filters go outside the cabinet - never inside the furnace.

Models that show this code

7 models in York UTEC IFC furnaces, York White-Rodgers IFC furnaces, York TM9V

Other codes on the same units

• 5 red flashes Rollout switch open / limit circuit open over 15 min
• 6 red flashes Pressure switch cycling lockout
• 7 red flashes Ignition failure lockout (retries)
• 8 red flashes Flame lost repeatedly (recycles)
• 10 red flashes Gas valve powered with no heat call
• 11 red flashes Limit open 5-15 minutes - blower failure
• 12 red flashes Hot surface igniter open / igniter failure
• 13 red flashes High-fire pressure switch open