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SERVICING
8. Using an ohmmeter, check for continuity from the #1
& #3 (common pins) to the transformer neutral or "C"
thermostat terminal. If you do not have continuity, the
motor may function erratically. Trace the common
circuits, locate and repair the open neutral.
9. Set the thermostat to "Fan-On". Using a voltmeter,
check for 24 volts between pin #15 (G) and common.
10. Disconnect power to compressor. Set thermostat to
call for cooling. Using a voltmeter, check for 24 volts
at pin #6 and or #14.
11. Set the thermostat to a call for heating. Using a
voltmeter, check for 24 volts at pin #2 and/or #11.
}
1
Lines 1 and 2 will be connected
for 12OVAC Power Connector
2
applications only
3
Gnd
4
AC Line Connection
5
AC Line Connection
OUT -
8
ADJUST +/-
7
Y1
6
COOL
5
DELAY
4
3
COMMON2
W/W1
2
COMMON1
1
16-PIN ECM HARNESS CONNECTOR
If you do not read voltage and continuity as described, the
problem is in the control or interface board, but not the
motor. If you register voltage as described, the ECM power
head is defective and must be replaced.
OUT +
16
15
G (FAN)
Y/Y2
14
13
EM Ht/W2
24 Vac (R)
12
HEAT
11
BK/PWM (SPEED)
10
O (REV VALVE)
9
Checking ECM Motor Windings
High Voltage!
Disconnect all power before servicing or
installing. Multiple power sources may be
present. Failure to do so may cause property
damage, personal injury or death.
1. Disconnect the 5-pin and the 16-pin connectors from
the ECM power head.
2. Remove the 2 screws securing the ECM power head
and separate it from the motor.
3. Disconnect the 3-pin motor connector from the power
head and lay it aside.
4. Using an ohmmeter, check the motor windings for
continuity to ground (pins to motor shell). If the
ohmmeter indicates continuity to ground, the motor is
defective and must be replaced.
5. Using an ohmmeter, check the windings for continuity
(pin to pin). If no continuity is indicated, the thermal
limit (over load) device may be open. Allow motor to
cool and retest.
3-pin motor
connector
16-pin
connector
5-pin
connector
Checking Compressor
Hermetic compressor electrical terminal venting can
be dangerous. When insulating material which supports
a hermetic compressor or electrical terminal suddenly
disintegrates due to physical abuse or as a result of an
electrical short between the terminal and the compressor
housing, the terminal may be expelled, venting the vapor and
liquid contents of the compressor housing and system.
If the compressor terminal PROTECTIVE COVER and
gasket (if required) are not properly in place and secured,
there is a remote possibility if a terminal vents, that the
vaporous and liquid discharge can be ignited, spouting
flames several feet, causing potentially severe or fatal
injury to anyone in its path.
This discharge can be ignited external to the compressor
if the terminal cover is not properly in place and if the
discharge impinges on a sufficient heat source.
WARNING
WARNING
20
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