Checking Air Circulator Blower Motor; Checking Duct Static - Maytag Goodman GM9C96 Service And Troubleshooting

SERVICING
2. Remove the thermostat low voltage wires at the furnace
integrated control module terminals.
With Power On (and Door Interlock Switch closed):
WARNING
L
INE VOLTAGE NOW PRESENT
3. Use a voltmeter, check voltage across terminals R and
C. Must read 24 VAC.
4. No voltage indicates faulty transformer, open fuse, bad
wiring, bad splice, or open door interlock switch.
5. Check transformer primary voltage at incoming line
voltage connections, fuse, splices, and blower door in-
terlock switch.
6. If line voltage is available to the primary side of trans-
former and not at secondary side, the transformer is
inoperative. Replace.
7. After completing check and/or replacement of trans-
former and check and/or repair of control circuit, rein-
stall blower compartment door.
8. Turn on electrical power and verify proper unit opera-
tion.
WARNING
L
INE VOLTAGE NOW PRESENT
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.

CHECKING AIR CIRCULATOR BLOWER MOTOR

(NINE-SPEED ECM MOTOR)
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. Check for any obstruction that would keep the fan wheel
/ fan motor from turning.
The nine-speed ECM motor requires a line voltage power
supply (black connected to CIRC H and white connected
to CIRC-N on the control board) as well as a signal on
one of the speed taps (T1-T5).
The speed tap voltage is D.C. and can vary depending
on SPEED SELECTION. The voltage reading from any
24
WARNING
one of the speed taps is referenced between the COM
terminal in the speed tap harness and the speed taps on
the control board. These voltages will range from 3-15
vDC depending upon speed selection.

CHECKING DUCT STATIC

The maximum and minimum allowable external static
pressures 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 insufficient
air that can cause excessive temperature rise, resulting 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 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. (Positive
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 conjunction 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,
registers, undersized and/or oversized poorly laid out duct
work.
Checking Static Pressure
.