GC9C96 Service Manual
SERVICING
27
A temperature activated manual reset control is mounted to
the manifold assembly as shown in the following illustration.
FLAME
ROLLOUT
SWITCHES
The control is designed to open should a ame roll out occur.
An over ring condition or ame 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 nd out why.
Possible causes could be ame impingement, orice
plate out of position, burners with excessive cross-
over slot dimension, over-ring, improper orices, im-
proper gas pressure, air leaking from around the heat
exchanger 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.
G
TG
T
R BR RG R
TG T T
T R R
B RT
R T RRT
G R JR R T
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 tri-
al 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 induced
draft motor, reinstall burner compartment door.
7. Turn on electrical power and verify proper unit opera-
tion.
A combination redundant operator type gas valve which
provides all manual and automatic control functions required
for gas red heating equipment is used.
The valve provides control of main burner gas ow, pressure
regulation, and 100 percent safety shut-o.
Two stage gas valves always require 24 volts between
common and low re (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.
Also see CHECKING GAS PRESSURE and CHECKING
PRESSURE SWITCHES.