SERVICING
44
S-9 CHECKING HIGH AND LOW VOLTAGE TO
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.
1.
Measure voltage between black and brown motor
leads. This should measure 208/230 volts depending
on your power supply.
2.
If voltage is present proceed to check fan relay
contacts and voltage.
CHECKING FAN RELAY CONTACTS - ECM FAN MOTOR
1.
Disconnect fan motor harness from plug on the UC
board.
2.
Energize the system in low stage and check voltage:
•
Pin 5(Blue wire) to Pin 3(Yellow wire) =
24VAC
3.
Energize the system in high stage and check volt-
age:
•
Pin 5(Blue wire) to Pin 3(Yellow wire) =
24VAC
•
Pin 5(Blue wire) to Pin 1(White wire) = 24
VAC.
4.
If voltage is present at these pins plug harness into
plug on PC board and check voltages at motor to test
for broken wires.
5.
If all voltages are present motor is defective and
needs to be replaced.
CHECKING RELAY CONTACTS - PSC FAN 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.
1. Disconnect the motor leads from 6-circuit fan motor wire
harness.
2. Connect a voltmeter between circuit 3 and circuits 2 (low
speed) or 1 (high speed).
NOTE:
Circuit 3 is connected directly to L2.
3. Energize the system at low or high stage.
WARNING
Line Voltage now present.
4. The measured voltage between circuit 3 and circuits 2 or
1 should be approximately 0VAC, which indicates the
relay contacts are closed. A voltage measurement of
approximately 115VAC indicates the relay is open. Re-
place the control if the relay checks open when it should
be closed. See notes and cautions below.
NOTE:
Ensure any ON delays have expired before making
voltage measurements
CAUTION:
Prolonged operation with the condenser fan
motor disconnected will cause the high pressure switch to
trip.
S-10A
COPELAND COMFORT ALERT
TM
-
UNITARY (UC) CONTROL DIAGNOSTICS
Applies to DX16TC, DX18TC, DZ16TC, DZ18TC models
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.
