Replacing Ecm Control Module; Figure 25 Control Disassembly; Figure 26 Winding Test; Figure 27 Drip Loop - Bard Q36A4DA Installation Instructions Manual

Replacing ECM Control Module

To replace the control module for the GE variable-speed indoor blower
motor, take the following steps:
1. The correct replacement module must be used. The controls are
factory programmed for specific operating modes. Even though
they look alike, different modules may have completely different
functionality.
USING THE WRONG CONTROL MODULE VOIDS ALL PRODUCT
WARRANTIES AND MAY PRODUCE UNEXPECTED RESULTS.
2. Begin by removing AC power from the unit being serviced. DO
NOT WORK ON THE MOTOR WITH AC POWER APPLIED. To
avoid electric shock from the motor's capacitors, disconnect
power and wait at least 5 minutes before opening motor.
3. It is not necessary to remove the motor from the blower
assembly, nor the blower assembly from the unit. Unplug the
two cable connectors to the motor control assembly. There are
latches on each connector. DO NOT PULL ON THE WIRES. The
plugs remove easily when properly released.
4. Locate the screws that retain to the motor control bracket to
the sheet metal of the unit and remove them. Remove two (2)
nuts that retain the control to the bracket and then remove
two (2) nuts that retain sheet metal motor control end plate.
Refer to Figure 25.
5. Disconnect the three (3) wires interior of the motor control
by using a thumb and forefinger to squeeze the latch tab and
the opposite side of the connector plug, gently pulling the
connector. DO NOT PULL ON THE WIRES, GRIP THE PLUG
ONLY. Refer to Figure 25.
6. The control module is now completely detached from the
motor. Verify with a standard ohmmeter that the resistance
from each motor lead (in the motor plug just removed) to the
motor shell is >100K ohms. Refer to Figure 26. (Measure to
unpainted motor end plate.) If any motor lead fails this test,
do not proceed to install the control module. THE MOTOR IS
DEFECTIVE AND MUST BE REPLACED. Installing the new
control module will cause it to fail also.
ECM
2.3/2.5
Figure 25
Control Disassembly
From Motor
Push until
Latch Seats
Over Ramp
Circuit
Board
Motor
Motor Connector
(3-pin)
Control Connector
(16-pin)
Power Connector
(5-pin)
7. Verify that the replacement control is correct for the
application. Refer to the manufacturer's authorized
replacement list. USING THE WRONG CONTROL WILL
RESULT IN IMPROPER OR NO BLOWER OPERATION.
Orient the control module so that the 3-wire motor plug can
be inserted into the socket in the control. Carefully insert the
plug and press it into the socket until it latches. A SLIGHT
CLICK WILL BE HEARD WHEN PROPERLY INSERTED.
8. Reverse Steps 3-5 to reconnect the motor control to
the motor wires, securing the motor control cover plate,
mounting the control to the bracket and mounting the
motor control bracket back into the unit. MAKE SURE THE
ORIENTATION SELECTED FOR REPLACING THE CONTROL
ENSURES THE CONTROL'S CABLE CONNECTORS WILL
BE LOCATED DOWNWARD IN THE APPLICATION SO THAT
WATER CANNOT RUN DOWN THE CABLES AND INTO THE
CONTROL. DO NOT OVERTIGHTEN THE BOLTS.
9. Plug the 16-pin control plug into the motor. The plug is
keyed. Make sure the connector is properly seated and
latched.
10. Plug the 5-pin power connector into the motor. Even though
the plug is keyed, OBSERVE THE PROPER ORIENTATION.
DO NOT FORCE THE CONNECTOR. It plugs in very easily
when properly oriented. REVERSING THIS PLUG WILL
CAUSE IMMEDIATE FAILURE OF THE CONTROL MODULE.
11. Final installation check. Make sure the motor is installed as
follows:
a. Motor connectors should be oriented between the 4
o'clock and 8 o'clock positions when the control is
positioned in its final location and orientation.
b. Add a drip loop to the cables so that water cannot enter
the motor by draining down the cables. Refer to Figure
27.
The installation is now complete. Reapply AC power to the HVAC
equipment and verify that the new motor control module is working
properly. Follow the manufacturer's procedures for disposition of
the old control module.
Figure 26
Winding Test
Motor Connector
(3-pin)
Figure 27
Drip Loop
Connector Orientation
Back of
Control
Between 4 and 8 o'clock
Motor OK when
R > 100k ohm
Drip Loop
Manual 2100-752B
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