A117_F: Detect RPM Motor Failure
Status
This is a critical fault. If this fault is active, the system is in a hard lockout and no operation will proceed.
Description
There is no RPM signal returned by the motor and the main limit has tripped.
Expected Operation
If the RPM signal is not detected and fault "T117_F Detect RPM Motor Failure" is active, and then the main limit trips, the control will go into a hard lockout. Fault will transition to an alarm "A117_F Detect RPM Motor Failure" and all operation will cease. Alarm "A093_F Internal Control Fault Detected" will also be logged. Hard lockout will only reset by cycling power to the control.
Cause
There could be multiple reasons causing this failure:
1. Broken RPM cable between the motor and the furnace control.
2. Bad blower motor.
3. Broken PWM cable between the furnace control and the motor.
4. Bad furnace control board.
5. No power to the blower motor control module.
6. No line voltage to the blower motor.
Solution
Depending on the cause of failure, you may need to:
1. Use new wire harness to ensure blower gets line voltage, blower control module gets power and the RPM/PWM cables are not broken.
2. Replace blower motor.
3. Replace furnace control.
