Lennox CBA25UHE Series Unit Information page 28

If the motor is not running, the following checks will di-
agnose whether it is operational. Always disconnect the
power to the HVAC system before disconnecting or
reconnecting any connectors to these motors. There
are two inputs needed to operate this motor, a high voltage
constant power source, and the low voltage communica-
tion 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. Ap-
plying incorrect high voltage to the motor may cause the
motor to not operate, or even damage the motor.
230VAC
VOLTAGE
FIGURE 26
Checking the Low-Voltage Communication Input
If no low voltage communication (typically 24VAC) is mea-
sured at the motor on taps 1-5, check the HVAC system
wiring, controls and demand call. Always check low volt-
age 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
motor 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.
3 - If the motor has proper high voltage as identified in
the previous section, and proper low voltage to a
programmed terminal, and motor is not operating,
the motor has failed. Replace motor.
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