Goodman GMEC80 Service Instructions Manual page 28

SERVICING
CHECKING FLAME ROLLOUT CONTROL
A temperature activated manual reset control is mounted to
the manifold assembly as shown in the following illustration.
ROLLOUT
SWITCHES
Flame Rollout Switch Location
(90% Upflow Furnace Shown, Counterflow Similar)
The control is designed to open should a flame roll out
occur. An over firing condition or flame impingement on
the heat shield may also cause the control to open. If the
rollout control opens, the air circulation blower will run
continuously.
1. Remove the burner compartment door to gain access
to the rollout switch(es) mounted to burner bracket.
2. Reset the manual roll out switch
3. Remove wires from roll out switch
4. Using an ohmmeter, check for continuity across the
switch.
5. If the switch will not close after manually resetting, it
must be replaced.
6. Measure the voltage between each side of the rollout
control and ground during the ignition attempt. If a roll
out switch has tripped, it is important to find out why.
Possible causes could be flame impingement, orifice
plate out of position, burners with excessive cross-over
slot dimension, over-firing, improper orifices, improper
gas pressure, air leaking from around the heat exchang-
er into the burner compartment, air leaking through the
heat exchanger itself.
7. After check and/or replacement of rollout switch, rein-
stall burner compartment door and verify proper unit
operation.
28
FLAME
INDUCED DRAFT BLOWER Motor
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 burner compartment door to gain access to
the induced draft blower motor.
2. Disconnect the motor wire leads from its connection
point at the induced draft motor.
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
obtained to ground, replace the motor.
5. If the windings have a continuity reading, reconnect
wires. Turn power on to the furnace and turn the
thermostat on in the heating mode. Check voltage
for 115V at the induced draft motor terminals during
the trial for ignition. If you have 115V and the motor
does not run, replace the induced draft motor.
6. After completing check and/or replacement of in-
duced draft motor, reinstall burner compartment
door.
7. Turn on electrical power and verify proper unit opera-
tion.
S-304 CHECKING GAS VALVE (Redundant)
A combination redundant operator type gas valve which pro-
vides all manual and automatic control functions required
for gas fired heating equipment is used.
The valve provides control of main burner gas flow, pres-
sure regulation, and 100 percent safety shut-off.
Two stage gas valves always require 24 volts between com-
mon and low fire (main coil) to open. Also, the furnace front
cover pressure switch is wired in series with the low (main)
solenoid of the gas valve. In the event of a non functioning
gas valve, always check the front cover pressure switch.
WARNING