SERVICING
77
To prevent the compressor from short cycling, a Time Delay
Relay (Cycle Protector) has been added to the low voltabe
circuit.
Testing a Run Capacitor Under Load
1. Measure the amperage of the wire from Herm on the
capacitor to start terminal on compressor.
2. Multiply the amperage reading by the constant of 2,652
3. Measure voltage across the capacitor between “HERM”
and “C” terminals this is the measured voltage across the
start and run terminals on the compressor.
4. Divide total from step 2 by the voltage measurement.
This total is the capacitance. This give a more accurate
measurement of the capacitor’s performance.
5. Read the rated MFD on the capacitor and compare to
your actual readings. If outside of +/- tolerance stated
on the capacitor, replacement of the capacitor may be
recommended.
Formula: Start Winding Amps x 2,652 ÷ capacitor
voltage = microfarads.
Checking Outdoor Fan and Blower Motors
(PSC Motors)
The auto reset fan motor overload is designed to protect
the motor against high temperature and high amperage
conditions by breaking the common circuit within the motor,
similar to the compressor internal overload. However, heat
generated within the motor is faster to dissipate than the
compressor, allow at least 45 minutes for the overload to
reset, then retest.
WARNING
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.
1. Remove the motor leads from its respective connection
points and capacitor (if applicable).
2. Check the continuity between each of the motor leads.
3. Touch one probe of the ohmmeter to the motor frame
(ground) and the other probe in turn to each lead.
If the windings do not test continuous or a reading is
obtained from lead to ground, replace the motor.
Checking Fan and Blower Motor (ECM Motors)
An ECM is an
Electronically Commutated Motor
which
offers many significant advantages over PSC motors.
The ECM has near zero rotor loss, synchronous machine
operation, variable speed, low noise, and programmable
air flow. Because of the sophisticated electronics within
the ECM motor, some technicians are intimated by the
ECM motor; however, these fears are unfounded. GE/
Regal Beloit offers two ECM motor testers, and with a VOM
meter, one can easily perform basic troubleshooting on
ECM motors. An ECM motor requires power (line voltage)
and a signal (24 volts) to operate. The ECM motor stator
contains permanent magnet. As a result, the shaft feels
“rough” when turned by hand. This is a characteristic of the
motor, not an indication of defective bearings.
WARNING
Line voltage now present
1. Disconnect the 5-pin connector from the motor.
2. Using a volt meter, check for line voltage at terminals #4 &
#5 at the power connector. If no voltage is present:
3. Check the unit for incoming power.
4. Check the control board.
5. If line voltage is present, reinsert the 5-pin connector and
remove the 16-pin connector.
6. Check for signal (24 volts) at the transformer.
7. Check for signal (24 volts) from the thermostat to the “G”
terminal at the 16-pin connector.
8. Using an ohmmeter, check for continuity from the #1 & #3
(common pins) to the transformer neutral or “C” thermostat
terminal. If you do not have continuity, the motor may
function erratically. Trace the common circuits, locate and
repair the open neutral.
9. Set the thermostat to “Fan-On”. Using a voltmeter, check
for 24 volts between pin # 15 (G) and common.
10. Disconnect power to compressor. Set thermostat to call
for cooling. Using a voltmeter, check for 24 volts at pin #6
and or #14.
11. Set the thermostat to a call for heating. Using a voltmeter,
check for 24 volts at pin #2 and/or #11.
Summary of Contents for ANX
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