Checking Capacitor; S-15A Resistance Check; S-16A Checking Air Circulator Blower Motor - Goodman ACS series Service Instructions Manual

SERVICING
S-15 CHECKING CAPACITOR
The direct drive motors are of the permanent split capacitor
design. A run capacitor is wired across the auxiliary and a
portion of the main windings. The capacitors primary func-
tion is to reduce the line current while greatly improving the
torque characteristics of a motor. This is accomplished by
using the 90° phase relationship between the capacitor cur-
rent and voltage in conjunction with the motor windings so
that the motor will give two phase operation when connected
to a single phase circuit. The capacitor also reduces the
line current to the motor by improving the power factor to the
load.
D
ISCHARGE CAPACITOR THROUGH A 20 TO 30 OHM RESISTOR
BEFORE HANDLING.
Two quick ways to test a capacitor are a resistance and a
capacitance check. Refer to the next two figures for proper
meter connections for the resistance and capacitance test-
ing of the capacitor.

S-15A Resistance Check

VOLT / OHM
METER
Testing Capacitor Resistance
HIGH VOLTAGE
D ALL
ISCONNECT POWER BEFORE SERVICING OR
M
INSTALLING THIS UNIT. ULTIPLE POWER SOURCES MAY
F
BE PRESENT. AILURE TO DO SO MAY CAUSE PROPERTY
DAMAGE, PERSONAL INJURY OR DEATH.
1. Remove blower compartment door to gain access to ca-
pacitor.
2. Discharge capacitor and remove wire leads.
3. Set an ohmmeter on its highest ohm scale and connect
the leads to the capacitor.
W ARNING
WARNING
a. Good Condition - indicator swings to zero and
slowly returns toward infinity.
b. Shorted - indicator swings to zero and stops there
- replace.
c. Open - no reading - replace. Reverse leads. Check
again no reading - replace.
d. Reverse leads and recheck.
S-16A CHECKING AIR CIRCULATOR BLOWER
MOTOR (PSC & ECM)
WARNING
D ALL
ISCONNECT POWER BEFORE SERVICING.
1. Remove blower compartment door to gain access to the
circulator blower motor and integrated ignition control.
2. Discharge the capacitor on (PSC) motors. Disconnect
the motor wire leads from its connection point at the
integrated ignition control module and capacitor if appli-
cable.
3. Using a ohmmeter, test for continuity between each of
the motor leads.
4. 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 ob-
tained to ground, replace the motor.
5. After completing check and/or replacement of circulator
blower motor or induced draft blower motor, reinstall
blower compartment door.
6. Turn on electrical power and verify proper unit operation.
The 80% and 90% Two-Stage Variable Speed furnaces in-
©
corporate the GE ICM or variable speed blower motors for
greater efficiency. ECM/ICM motors vary the motor RPMs
to provide a set volume of air over a wide range of conditions.
These motors use an electronic control module attached to
the motors end bell to control motor operation. Some unique
features of these motors are:
1. Constant Airflow. These motors will maintain constant
airflow over a wide static pressure range. In other words,
as the static increases so does the motors RPM so that
a constant CFM is maintained.
NOTE: The motor in these units will move more air under
higher static conditions than a similar sized unit using a
PSC motor. Because this motor does not load up and re-
duce airflow like a PSC motor, in some undersized duct
installations this may cause noise or high airflow complaints.
2. Ramp-up/Ramp-down feature. These motors ramp up
and down at the beginning or end of a cycle to reduce air
rush noise.
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