Daikin VRV RXYQ72-384XAYCA, Service Manual

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Check SiUS342004EB
379 Part 6 Service Diagnosis
Warning
Warning
4.14 Fan Motor Connector Check for FXTQ-TA, FXTQ-TB
CHECK 19
CHECKING EMERSON ULTRATECH
TM
ECM MOTORS
The FXTQ-TA and FXTQ-TB models utilize an Emerson, 4-wire variable speed ECM blower motor.
The ECM blower motor provides constant CFM.
The motor is a serially communicating variable speed motor. Only four wires are required to control
the motor: +Vdc, Common, Receive, and Transmit.
The +Vdc and Common wires provide power to the motor's low voltage control circuits.
General Checks / Considerations
Emerson UltraCheck-EZ
TM
Diagnostic Tool
The Emerson UltraCheck-EZ
TM
diagnostic tool may be used to diagnose the ECM motor.
HIGH VOLTAGE!
Disconnect ALL power before servicing or installing. Multiple power sources may be present.
Failure to do so may cause property damage, personal injury or death.
To use the diagnostic tool, perform the following steps:
Line Voltage now present.
1. Check power supply to the air handler or modular blower. Ensure power supply is within
the range specified on rating plate.
2. Check motor power harness. Ensure wires are continuous and make good contact when
seated in the connectors. Repair or replace as needed.
3. Check motor control harness. Ensure wires are continuous and make good contact when
seated in the connectors. Repair or replace as needed.
4. Check blower wheel. Confirm wheel is properly seated on motor shaft. Set screw must
be on shaft flat and torqued to 165 in-lbs minimum. Confirm wheel has no broken or
loose blades. Repair or replace as needed.
5. Ensure motor and wheel turn freely. Check for interference between wheel and housing
or wheel and motor. Repair or replace as needed.
6. Check housing for cracks and/or corrosion. Repair or replace as needed.
7. Check motor mounting bracket. Ensure mounting bracket is tightly secured to the
housing. Ensure bracket is not cracked or broken.
1. Disconnect power to the air handler.
2. Disconnect the 4-circuit control harness from the motor.
3. Plug the 4-circuit connector from the diagnostic tool into the motor control connector.
4. Connect one alligator clip from the diagnostic tool to a ground source.
5. Connect the other alligator clip to a 24VAC source.
NOTE:
The alligator clips are NOT polarized.
NOTE: The Ultra Check-EZ
TM
diagnostic tool is equipped with a non-replaceable fuse.
Connecting the tool to a source other than 24VAC could damage the tool and cause the
fuse to open. Doing so will render the diagnostic tool inoperable.
6. Turn on power to air handler or modular blower.
7. Depress the orange power button on the diagnostic tool to send a run signal to the motor.
Allow up to 5 seconds for the motor to start.
NOTE: If the orange power button does not illuminate when depressed, the tool either
has an open fuse or is not properly connected to a 24VAC source.