The pressure switches are normally-open (closed during operation)
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 insufficient airflow (combustion
air and flue products) through the heat exchanger and/or blocked
condensate drain conditions.
The flame sensor is a probe mounted to the burner/manifold as-
sembly which uses the principle of flame rectification to determine
the presence or absence of flame.
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
servicing 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 procedure is applicable to both installed and uninstalled
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.
Refer to the Diagnostic Codes chart for assistance in deter-
mining the source of unit operational problems.
Red LED Flash
Flash Codes stored in memory (auto-erased after 14 days)
System Lockout (Retries Exceeded)
Pressure Switch stuck Closed
Pressure Switch stuck Open
Open High Temperature Limit Switch
Flame Sensed>4.25 Seconds with Gas
Open High Temperature Limit Switch
Igniter Relay Fault
Inducer Relay Error
Flash Codes NOT stored in memory
Low Flame Sense Signal
Control Failure / No Power / Internal Fault /
IRQ Loss. Gas Heating Lockout (Gas valve
energized when it should be de-energized)
Or Gas Valve De-energized when it should
The last five fault codes stored can be displayed on the
diagnostic LED. When the control is in standby mode (no
call for heat or cool), press the FAULT RECALL switch for
approximately two seconds or until the diagnostic LED turns
off. Release the switch and the LED will remain off for two
seconds. Then the fault codes will display beginning with
the most recent fault first with a two second pause between
codes. After the stored fault codes have all displayed,
the LED will remain off for two seconds and then turn on
to indicate return to normal status. While displaying the
stored fault codes, the control will ignore any new call for
heat, cool or fan.
HIGH VOLTAGE !
O AVOID PERSONAL INJURY OR DEATH DUE TO
DISCONNECT ELECTRICAL POWER
PERFORMING ANY SERVICE OR MAINTENANCE
FAULT CODE RESET
The stored fault codes can be erased from memory. When
the control is in standby mode (no call for heat or cool),
press the FAULT RECALL switch for five to ten seconds or
until the diagnostic LED begins to rapid flash. When the
switch is released, the LED will turn off for two seconds to
indicate the codes are erased. After two seconds the LED
will turn on to indicate return to normal status. If the switch
is held pressed for over ten seconds the rapid flash will stop
and the LED will be on to indicate return to normal status.
Error / Condition