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SERVICE
Troubleshooting NIDEC SELECTECH
Series ECM Motors
If the Motor Is Running
1. It is normal for the motor to rock back and forth
on start up. Do not replace the motor if this is the
only problem identified.
2. If the system is excessively noisy, does not appear
to change speeds in response to a demand (Heat,
Cool, Other) or is having symptoms during the
cycle such as tripping limit or freezing coil, check
the following:
A. Wait for programmed delays to time out.
B. Ensure that the motors control inputs are
wired as shown in the factory-supplied wiring
diagram to ensure motor is getting proper
control signals and sequencing.
C. Remove the filter and check that all dampers,
registers and grilles are open and free flowing.
If removing the filters corrects the problem,
clean or replace with a less restrictive filter.
Also check and clean the blower wheel or coil
as necessary.
↓
L2 LINE
EARTH
POWER
GROUND
NOTE: MOTOR IS CONSTANTLY
POWERED BY LINE VOLTAGE
Manual 2100-720E
Page
28 of 42
FIGURE 23
Motor Connections
↓
L1 LINE
POWER
D. Check the external static pressure (total of
both supply and return) to ensure it is within
the range as listed on the unit serial plate. If
higher than allowed, additional duct work is
needed.
E. If the motor does not shut off at the end of the
cycle, wait for any programmed delays to time
out (no more than 90 seconds). Also make
sure that there is no call for "Continuous Fan"
on the G terminal.
F.
If the above diagnostics do not solve the
problem, confirm the voltage checks in the
next section below, then continue with the
Model SelecTech Communication Diagnostics.
If the Motor Is Not Running
1. Check for proper high voltage and ground at the L/
L1, G, N/L2 connections at the motor (see Figure
23). Correct any voltage issues before proceeding
to the next step. The SelecTech motor is voltage
specific. Only the correct voltage should be applied
to the proper motor. Input voltage within plus
or minus 10% of the nominal line power VAC is
acceptable.
LINE
POWER
GROUND
LINE
POWER
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