SERVICING
30
Checking ECM Motors
ECMmotors connect directly to the AC Line Voltage.
DO
NOT
insert contactors in series with the ECM Motor AC
Line. The control is powered continuously to insure reliable
start-up. The connector plug is polarized, verify and reverify
correct connector orientation before applying power.
DO
NOT
force plug into motor and make sure power is off
before inserting power connector.
DO NOT
apply voltage to
terminals 1 or 2.
G
eneral Checks/Considerations
1. Check power supply to the furnace. Ensure power
supply is within the range specified on rating plate.
2. Check motor power harness. Ensure wires are
continuous and make good contact when seated in the
connectors. Repair or replace as needed.
3. Check motor control harness. Ensure wires are
continuous and make good contact when seated in the
connectors. Repair or replace as needed.
4. Check thermostat and thermostat wiring. Ensure
thermostat is providing proper cooling/heating/
continuous fan demands. Repair or replace as needed.
5.
Check blower wheel. Confirm wheel is properly seated
on motor shaft. Set screw must be on shaft flat and
torqued to 165 in-lbs minimum. Confirm wheel has no
broken or loose blades. Repair or replace as needed.
6. Ensure motor and wheel turn freely. Check for
interference between wheel and housing or wheel and
motor. Repair or replace as needed.
7. Check housing for cracks and/or corrosion. Repair or
replace as needed.
8. Check motor mounting bracket. Ensure mouting bracket
is tightly secured to the housing. Ensure bracket is not
cracked or broken.
UltraCheck-EZ
TM
Diagnostic Tool
The UltraCheck-EZ
TM
diaganostic tool is the preferred
method (part # UTT-01) to diagnose the ECM motor.
WARNING
High Voltage!
Disconnect all power before servicing
or installing this unit. Multiple power
sources may be present. Failure to do
so may cause property damage, personal
injury or death.
To use the diagnostic tool, perform the following steps:
1. Disconnect power to the furnace.
2. Disconnect the 4-circuit control harness from the motor.
3. Plug the 4-circuit connector from the diagnostic tool into
the motor control connector.
4. Connect one alligator clip from the diagnostic tool to a
ground source.
5. Connect the other alligator clip to a 24VAC source.
NOTE: The alligator clips are NOT polarized.
NOTE: The UltraCheck-EZ
TM
diagnostic tool is
equipped with a nonreplaceable fuse. Connecting
the tool to a source other than 24VAC could
damage the tool and cause the fuse to open.
Doing so will render the diagnostic tool
inoperable.
6. Turn on power to the furnace.
WARNING
Line voltage now present
7. Depress the orange power button on the diagnostic tool
to send a run signal to the motor. Allow up to 5 seconds
for the motor to start.
NOTE: If the orange power button does not
illuminate when depressed, the tool either has
an open fuse or is not properly connected to a
24VAC source.
8. The green LED on the diagnostic tool will blink indicating
communications between the tool and motor. See table
below for indications of tool indicators and motor actions.
Replace or repair as needed.
Power
Button
Green
LED
Motor
Action
Indication(s)
OFF
OFF
Not
Rotating
Confirm 24VAC to
UltraCheck-EZ
TM
tool.
If 24VAC is confirmed,
diagnostic tool is
inoperable.
ON
Blinking Rotating
Motor and control/end
bell are functioning
properly.
ON
OFF
Rotating Replace motor
control/end bell.
ON
Blinking
Not
Rotating
Check motor (see
Motor Checks
below).
ON
OFF
Not
Rotating
Replace motor
control/end bell; verify
motor (see
Motor
Checks
below).
9.
Depress the orange power button to turn off motor.
10. Disconnect power. Disconnect diagnostic tool.
11. Reconnect the 4-wire harness from control board to
motor.
