Daikin ComfortNet DX7TC Service Instructions Manual page 76

SERVICING
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1
Lines 1 and 2 will be connected
for 12OVAC Power Connector
2
applications only
3
Gnd
4
AC Line Connection
5
AC Line Connection
5. Measure voltage between pins 4 and 3. Voltage should be
approximately half of the voltage measured in step 4.
6. Measure voltage between pins 5 and 3. Voltage should be
approximately half of the voltage measured in step 4.
7. If no voltage is present, check supply voltage to air
handler or modular blower. See section S-1.
8. Disconnect power to air handler or modular blower.
Reconnect the 5-circuit power harness disconnected in step
2.
Electrical Checks - Low Voltage Control Circuits
1. Turn on power to air handler or modular.
Line Voltage now present.
2. Check voltage between pins on the 4-wire motor control
harness between the motor and control board.
3. Voltage on pins should read:
Pins 1 to 4 = 3.3vdc
Pins 1 to 2 = 3.3vdc
Pins 3 to 4 = 15vdc
Motor Control/End Bell Checks
HIGH VOLTAGE
Disconnect ALL power before servicing or installing
this unit. Multiple power sources may be present.
Failure to do so may cause property damage, personal
injury or death.
1. Disconnect power to air handler or modular blower.
NOTE: Motor contains capacitors that can hold a charge
for several minutes after disconnecting power. Wait 5
minutes after removing power to allow capacitors to
discharge.
2. Disconnect the motor control harness and motor power
harness.
76
WARNING
WARNING
3. Remove the blower assembly from the air handler or
modular blower.
4. Remove the (3) screws securing the control/end bell to
the motor. Separate the control/end bell. Disconnect the
3-circuit harness from the control/end bell to remove the
control/end bell from the motor.
5. Inspect the NTC thermistor inside the control/end bell
(see figure below). Replace control/end bell if thermistor
is cracked or broken.
6. Inspect the large capacitors inside the control/end bell
(see figure below). Replace the control/end bell if any of
the capacitors are bulging or swollen.
7. Locate the 3-circuit connector in the control/end bell.
Using an ohmmeter, check the resistance between each
terminal in the connector. If the resistance is 100 W or
greater, the control/end bell is functioning properly.
Replace the control/end bell if the resistance is lower than
100 W.
8. Reassemble motor and control/end bell in reverse of
disassembly. Replace blower assembly into air handler or
modular blower.