York TM9T HVAC System Error Codes

High-Efficiency HVAC System. 10 error codes documented.

Severity breakdown: 6 critical , 4 warning

Error Codes

Code	Description	Severity
AF	Low Flame Current	Critical
R1	Flame Without Call	Critical
R5	Rollout Switch Open	Critical
R6	Gas Valve Failure	Critical
R7	Ignition Lockout	Critical
R9	Reversed Polarity	Critical
A4	Improper Thermostat Wiring	Warning
R2	Pressure Switch Stuck Closed	Warning
R3	Pressure Switch Stuck Open	Warning
R4	High Limit Switch Open	Warning

Cross-Reference: Shared Codes with Other York Models

Model	Type	Shared Codes	Unique to That Model
YXV	—	10 / 10	—
YXT	—	10 / 10	—
YCS	—	10 / 10	—
YZV	—	10 / 10	—
YZT	—	10 / 10	—
YZB	—	10 / 10	—
TM9V	—	10 / 10	—
TM8Y	—	10 / 10	—
LX Series	—	10 / 10	—
AHE	—	10 / 10	—
Packaged	—	10 / 10	—