Service Manual

Troubleshooting by Error Codes SiUS281811E
198 Part 6 Service Diagnosis
Reference
4.12 Low Indoor Airflow
Error Code A6-21
Applicable
Models
FTQ-TA
Outline Error is issued if the indoor unit determines that the indoor fan motor rotation is insufficient,
regardless of the rotation command from indoor unit.
Error Decision
Conditions
 Determining successive abnormalities
Checks the rotation speed at 5-second intervals using the feedback of the fan motor.
If that figure exceeds 50 rpm and falls below 150 rpm 10 times successively, it is deemed
abnormal operation.
If, during operation, the rotation command is stopped, the 5-second interval check is halted and
the counted number will be cleared.
 Determining long-term abnormalities
Checks the rotation speed at 5-second intervals using the feedback of the fan motor.
Performs rotation sampling 720 times (takes approx. one hour), and if the rotation speed
exceeds 50 rpm and falls below 150 rpm over 360 times, it is deemed abnormal operation.
When the counter reaches 720 times, the counted number will be cleared and the 720 times
sampling restarts.
If, during this, the rotation command is stopped, the 5-second interval check is halted, but the
counted number will be kept.
When the rotation command is restarted, the checks will resume.
Error Reset
Conditions
 Determining successive abnormalities
Checks the rotation speed at 5-second intervals using the feedback of the fan motor.
If that figure exceeds 150 rpm even once, the error will be cleared.
 Determining long-term abnormalities
Checks the rotation speed at 5-second intervals using the feedback of the fan motor.
If that figure exceeds 150 rpm 36 times successively, the error will be cleared.
At that point, the counted number and sampling number will be cleared, and the 720 times
sampling starts again from the beginning.
Supposed
Causes
 Fan or motor obstruction
 Blocked filters
 Restrictive ductwork or ductwork undersized
 Wiring disconnected
 Wrong outdoor and indoor combination
 Indoor fan motor failure
Corrective
Actions
 Check for obstruction on the fan or motor.
 Check ductwork and filter for blockage.
 Clean filters.
 Remove obstruction. Verify all registers are fully open.
 Check the connections and the rotation of the motor.
 Verify the input voltage at the motor.
 Verify ductwork is appropriately sized for system. Resize or replace ductwork if needed.
 Replace motor.
CHECK 19 Refer to page 280.