Checking Air Circulator Blower Motor; Checking Duct Static - Goodman GMES8 U Series 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):
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.

CHECKING AIR CIRCULATOR BLOWER MOTOR

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.
3. Check wiring, the motor has two wiring harnesses, a main
harness and a control harness. The main power harness
has: White neutral wire connected to the NEUTRAL
terminal on the control board. Black wire connected to
the MOTOR terminal on the control board. Red wire
connected to the COM terminal, which is a female spade
connection next to the HEAT and COOL wires on the
control board. Green ground wire connected to cabinet
ground. The control power harness has: Blue wire
connected to HEAT on the control board. (Medium High
Speed)Red wire connected to RED on the control board.
(High Speed) Orange wire connected to FAN on the
control board. (Medium Speed) Black (Low Speed) and
Brown (Medium Low Speed) wires connected to PARK on
the control board. The multi-speed ECM motor requires
a line voltage power supply (black connected to MOTOR
and white connected to neutral on the control board) as
well as a signal on one of the speed taps. The signal to
the motor is a 24vAC signal to the speed tap. .
WARNING
WARNING
D ALL
ISCONNECT POWER BEFORE SERVICING.

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 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. (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
WARNING
.
17