S-15A Resistance Check; Checking Air Circulator Blower Motor (Psc); Checking Duct Static - Goodman AMH8 Service Instructions Manual

SERVICING

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
capacitor.
2. Discharge capacitor and remove wire leads.
3. Set an ohmmeter on its highest ohm scale and connect
the leads to the capacitor.
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-16 CHECKING AIR CIRCULATOR BLOWER MO-
TOR (PSC)
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 ap-
plicable.
3. Using a ohmmeter, test for continuity between each of
the motor leads.
WARNING
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 circula-
tor blower motor or induced draft blower motor, rein-
stall blower compartment door.
6. Turn on electrical power and verify proper unit opera-
tion.
WARNING
D ALL
ISCONNECT POWER BEFORE SERVICING.
S-200 CHECKING DUCT STATIC
The maximum and minimum allowable external static pres-
sures are found in the specification section. These tables
also show the amount of air being delivered at a given
static by a given motor speed or pulley adjustment.
The furnace motor cannot deliver proper air quantities
(CFM) against statics other than those listed.
Too great of an external static pressure will result in insuffi-
cient air that can cause excessive temperature rise, result-
ing in limit tripping, etc. Whereas not enough static may
result in motor overloading.
To determine proper air movement, proceed as follows:
1. With clean filters in the furnace, use a draft gauge
(inclined manometer) to measure the static pressure of
the return duct at the inlet of the furnace. (Negative
Pressure)
2. Measure the static pressure of the supply duct. (Posi-
tive Pressure)
3. Add the two (2) readings together for total external static
pressure.
NOTE: Both readings may be taken simultaneously and
read directly on the manometer if so desired. If an air
conditioner coil or Electronic Air Cleaner is used in con-
junction with the furnace, the readings must also include
theses components, as shown in the following drawing.
4. Consult proper tables for the quantity of air.
If the total external static pressure exceeds the minimum or
maximum allowable statics, check for closed dampers, reg-
isters, undersized and/or oversized poorly laid out duct
work.
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