Table of Contents
Advertisement
SERVICING
Volt / Ohm
Meter
AMMETER
TESTING CAPACITANCE
S-16A CHECKING FAN AND BLOWER MOTOR
WINDINGS (PSC MOTORS)
The auto reset fan motor overload is designed to protect the
motor against high temperature and high current conditions by
breaking the common circuit within the motor, similar to the
compressor internal overload. However, heat generated within
the motor is faster to dissipate than the compressor, allow at
least 45 minutes for the overload to reset, then retest.
1. Remove the motor leads from its respective connection
points and capacitor (if applicable).
2. Check the continuity between each of the motor leads.
3. Touch one probe of the ohmmeter to the motor frame
(ground) and the other probe in turn to each lead.
If the windings do not test continuous or a reading is obtained
from lead to ground, replace the motor.
S-16B CHECKING FAN AND BLOWER MOTOR
(ECM MOTORS)
An ECM (Electronically Commutated Motor) has near zero ro-
tor loss, synchronous machine operation, variable speed, low
noise and programmable air flow. The ECM motor stator con-
tains a permanent magnet which results in the shaft feeling
"rough" when turned by hand. This is a characteristic of the
motor, not an indication of defective bearings. An ECM motor
requires power (line voltage) and a signal (24 volts) to operate.
Use an ECM motor tester (GE Techmate or equivalent) with a
VOM meter to perform basic troubleshooting on ECM motors.
Line Voltage now present.
1. Disconnect the 5-pin connector from the motor.
32
2. Using a volt meter, check for line voltage at terminals #4
3. Check the unit for incoming power. See section S-1.
4. Check the control board, See section S-313.
15 AMP FUSE
5. If line voltage is present, reinsert the 5-pin connector and
6. Check for signal (24 volts) at the transformer.
7. Using an ohmmeter, check for continuity from the #1 & #3
8. Set the thermostat to "Fan-On". Using a voltmeter, check
9. Disconnect power to compressor. Set thermostat to call
10. Set the thermostat to a call for heating. Using a voltmeter,
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.
and #5 at the power connector. If no voltage is present,
proceed to step 3. If voltage is present, skip to step 5.
remove the 16-pin connector.
(common pins) to the transformer neutral or "C" thermostat
terminal. If you do not have continuity, the motor may func-
tion erratically. Trace the common circuits, locate and re-
pair the open neutral.
for 24 volts between pin # 15 (G) and pins #1 or #3 (com-
mon).
for cooling. Using a voltmeter, check for 24 volts at pin # 6
and/or #14, and pins #1 and/or #3 (common).
check for 24 volts at pin #2 and/or #13, and pins #1 and/or
#3 (common).
}
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
5 PIN POWER CONNECTOR
OUT -
8
ADJUST +/-
7
Y1
6
COOL
5
DELAY
4
3
COMMON2
W/W1
2
COMMON1
1
16-PIN ECM HARNESS CONNECTOR
16
OUT +
15
G (FAN)
14
Y/Y2
13
EM Ht/W2
24 Vac (R)
12
HEAT
11
BK/PWM (SPEED)
10
O (REV VALVE)
9
Advertisement
Chapters
Table of Contents
