104
SERVICING
6. The control module is now completely detached from the
motor. Verify with a standard ohmmeter that the resis-
tance from each motor lead (in the motor plug just re-
moved) to the motor shell is greater than 100k ohms.
(Measure resistance 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 fail also.
7.
Verify that the replacement control module is correct
for your application. If so, orient the new module next
to the motor and carefully insert the plug removed in
step 5. Be sure the plug latches. It will click when prop-
erly inserted.
8.
Install the new control module back on the motor being
careful to engage the locating notches onto the appro-
priate mating tabs. Replace the two 1/4" hex head bolts.
Tighten the bolts snugly. It is not necessary to over-
tighten.
Note
: Before replacing the blower/motor assembly, it is
important to look at the installation to see if some applica-
tion fault has caused the motor to fail.
Is there any evidence of water damage to the failed control?
(Corrosion on the inside or outside of the casting.) If yes,
do a moisture check.
9.
Re-install the blower/motor assembly into the furnace.
10. Plug the 16-pin control plug into the motor. The plug is
keyed. Make sure the connector is properly seated and
latched.
11. Plug the 5 pin power connector into the motor even
though the plug is keyed, observe the proper orienta-
tion. Do not force the connector. It plugs in very easily
when properly oriented.
Reversing this plug will cause
immediate failure of the control module
.
12. Final installation check. Make sure the motor is installed
as follows:
a.
As far into the blower housing as possible.
b.
Belly bands not covering vent holes or on the control
module.
c.
Motor connectors should oriented as to prevent the ac-
cumulation of moisture in the control.
d.
Use wire ties to create a drip loop in the motor cables.
13. The installation is now complete. Reapply power to the
furnace and verify that the new motor control module is
working properly.
For complete troubleshooting information on the variable
speed air circulator blower motors, refer to the
Troubleshoot-
ing Chart for ECM/ICM Variable Speed Air Circulator Blower
Motors
on the next page of this manual.