GMES96-U Installation Manual
31
• Circulator blower runs, integrated control module
monitors safety circuits continuously.
• R and G thermostat contacts open, completing the
call for fan.
• Circulator blower is de-energized.
• EAC terminal is de-energized.
• Furnace awaits next call from thermostat.
O
PERATIONAL
C
HECKS
S
AFETY
C
IRCUIT
D
ESCRIPTION
T
O
AVOID
PERSONAL
INJURY
OR
DEATH
,
DO
NOT
REMOVE
ANY
INTERNAL
COMPARTMENT
COVERS
OR
ATTEMPT
ANY
ADJUSTMENT
.
E
LECTRICAL
COMPONENTS
ARE
CONTAINED
IN
BOTH
COMPARTMENTS
.
C
ONTACT
A
QUALIFIED
SERVICE
AGENT
AT
ONCE
IF
AN
ABNORMAL
OPERATION
SHOULD
DEVELOP
.
CAUTION
A number of safety circuits are employed to ensure safe and
proper furnace operation. These circuits serve to control any
potential safety hazards and serve as inputs in the monitoring
and diagnosis of abnormal function. These circuits are continu-
ously monitored during furnace operation by the integrated con-
trol module.
INTEGRATED CONTROL MODULE
The integrated control module is an electronic device which, if a
potential safety concern is detected, will take the necessary pre-
cautions and provide diagnostic information through an LED.
PRIMARY LIMIT
The primary limit control is located on the partition panel and
monitors heat exchanger compartment temperatures. It is a
normally-closed (electrically), automatic reset, temperature-ac-
tivated sensor. The limit guards against overheating as a result
of insufficient conditioned air passing over the heat exchanger.
AUXILIARY LIMIT
The auxiliary limit controls are located on or near the circulator
blower and monitors blower compartment temperatures. They
are a normally-closed (electrically), manual-reset sensors. These
limits guard against overheating as a result of insufficient condi-
tioned air passing over the heat exchanger.
BURNER TEMPERATURE SWITCH
The burner temperature switch is mounted on the burner
assembly to monitor the burner box temperature. It is nor-
mally closed (electrically), auto-reset sensor. This switch
guards against the burner flames not being properly drawn into
the heat exchanger.
PRESSURE SENSOR
Pressure sensor is mounted on the induced draft blower. Its
function is to regulate the induced draft blower’s speed in
order to maintain proper air-fuel ratio for clean and reliable
combustion.
PRESSURE SWITCHES
The pressure switches are normally-open (closed during opera-
tion) negative air pressure-activated switches. They monitor
the airflow (combustion air and flue products) through the heat
exchanger via pressure taps located on the induced draft blower
and the coil front cover. These switches guard against insuffi-
cient airflow (combustion air and flue products) through the heat
exchanger and/or blocked condensate drain conditions.
FLAME SENSOR
The flame sensor is a probe mounted to the burner assembly
which uses the principle of flame rectification to determine the
presence or absence of flame.
T
ROUBLESHOOTING
ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS
NOTE: Discharge body’s static electricity before touching unit.
An electrostatic discharge can adversely affect electrical
components.
Use the following precautions during furnace installation and ser-
vicing to protect the integrated control module from damage. By
putting the furnace, the control, and the person at the same
electrostatic potential, these steps will help avoid exposing the
integrated control module to electrostatic discharge. This pro-
cedure is applicable to both installed and uninstalled (ungrounded)
furnaces.
1. Disconnect all power to the furnace. Do not touch the
integrated control module or any wire connected to the
control prior to discharging your body’s electrostatic
charge to ground.
2. Firmly touch a clean, unpainted, metal surface of the
furnace away from the control. Any tools held in a person’s
hand during grounding will be discharged.
3. Service integrated control module or connecting wiring
following the discharge process in step 2. Use caution not
to recharge your body with static electricity; (i.e., do not
move or shuffle your feet, do not touch ungrounded
objects, etc.). If you come in contact with an ungrounded
object, repeat step 2 before touching control or wires.
4. Discharge your body to ground before removing a new
control from its container. Follow steps 1 through 3 if
installing the control on a furnace. Return any old or new
controls to their containers before touching any ungrounded
object.
TROUBLESHOOTING CHART
Refer to the Troubleshooting Codes chart for assistance in de-
termining the source of unit operational problems.