Lennox CBA27UHE-018, Руководство пользователя

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Page 31
DRIP LOOP
BACK OF
UNIT
CONNECTOR
ORIENTATION (BETWEEN
4 AND 8 O'CLOCK)
DRIP LOOP
FIGURE 16
DANGER
Disconnect power from unit and wait
at least five minutes to allow capaci­
tors to discharge before attempting to
service motor. Failure to wait may
cause personal injury or death.
INDOOR BLOWER MOTOR (B3) CONTROL TROU­
BLESHOOTING (REGAL-BELOIT)
Before troubleshooting any HVAC system, it is a good prac­
tice to become familiar with the components and wiring dia­
gram. On fan motor systems it is a good practice to check
the tap selections and delay settings.
If the motor is running but the system is noisy, shutting
down on its limits or safeties or the evaporator coil is freez­
ing, there is a good chance the motor is good. The problem
is most likely external to the motor.

Check the tap selections using the HVAC OEM guide

Check the air distribution system components for dirt
load and closed dampers, registers and grilles.

Measure the total external static pressure. Make re­
pair(s) if above the recommended maximum level and con­
firm airflow at the new total ESP with the air flow tables (be­
ginning on page 4). Aftermarket filter sizing is a common
issue.
If the motor is not running , the following checks will dia­
gnose whether it is operational. Always disconnect the
power to the HVAC system before disconnecting or re­
connecting any connectors to these motors.
There are
two inputs needed to operate this motor, a high voltage con­
stant power source, and the low voltage communication
that selects the torque value in each tap per demand.
Checking 230VAC Voltage Input
First check the high voltage to terminals (L) and (N). There
should be 230VAC on these two terminals whenever there
is power to the system, regardless of a demand call. Apply­
ing incorrect high voltage to the motor may cause the motor
to not operate, or even damage the motor.
230VAC
VOLTAGE
FIGURE 17
Checking the Low-Voltage Communication Input
If no low voltage communication (typically 24VAC) is meas­
ured at the motor on taps 1-5, check the HVAC system wir­
ing, controls and demand call. Always check low voltage
between terminals 1-5 and (C) at the motor, never ground.
Once the problem is corrected, confirm that the low voltage
communication is applied to a programmed tap. If proper
low voltage communication is present at a programmed
tap, with proper high voltage to the motor and it still does not
operate, the motor is failed.
1- Initiate a demand from the thermostat and check the
voltage between the common and the appropriate mo­
tor terminal 1- 5. Confirm the meter is set to the 24VAC.
2- If the low voltage communication is not present, check
the demand from the thermostat. Also check the output
terminal and wires from the K20 blower relay.
3- If the motor has proper high voltage as identified in the
previous section, and proper low voltage to a pro­
grammed terminal, and motor is not operating, the mo­
tor has failed. Replace motor.