74
SERVICING
TROUBLESHOOTING
Ignition Control Error Codes
The following presents probable causes of questionable
unit operation. Refer to
Diagnostic Indicator Chart
for
an interpretation of the signal and to this section for an
explanation.
Remove the control box access panel and note the number
of diagnostic LED flashes. Refer to
Diagnostic Indicator
Chart
for an interpretation of the signal and to this section
for an explanation.
Internal Control Failure
If the integrated ignition control in this unit encounters an
internal fault, it will go into a “hard” lockout and turn off
the diagnostic LED. If diagnostic LED indicates an internal
fault, check power supply to unit for proper voltage, check
all fuses, circuit breakers and wiring. Disconnect electric
power for five seconds. If LED remains off after restoring
power, replace control.
Abnormal Operation - Heating Codes
External Lockout (1 FLASH CODE)
An external lockout occurs if the integrated ignition control
determines that a measurable combustion cannot be
established within three (3) consecutive ignition attempts.
If flame is not established within the seven (7) second trial
for ignition, the gas valve is deenergized, 15 second inter-
purge cycle is completed, and ignition is reattempted. The
control will repeat this routine three times if a measurable
combustion is not established. The control will then shut
off the induced draft blower and go into a lockout state.
If flame is established but lost, the control will energize
the circulator blower at the heat speed and then begin a
new ignition sequence. If flame is established then lost on
subsequent attempts, the control will recycle for four (4)
consecutive ignition attempts (five attempts total) before
locking out.
The diagnostic fault code is 1 flash for a lockout due to
failed ignition attempts or flame dropouts. The integrated
control will automatically reset after one hour, or it can be
reset by removing the thermostat signal or disconnecting
the electrical power supply for over five seconds. If the
diagnostic LED indicates an external lockout, perform the
following checks:
•
Check the supply and manifold pressures
•
Check the gas orifices for debris
•
Check gas valve for proper operation
•
Check secondary limit
A dirty filter, excessive duct static, insufficient air flow, a
faulty limit, or a failed circulator blower can cause this
limit to open. Check filters, total external duct static,
circulator blower motor, blower motor speed tap (see
wiring diagram), and limit. An interruption in electrical
power during a heating cycle may also cause the
auxiliary limit to open. The automatic reset secondary
limit is located on top of the circulator blower assembly.
•
Check rollout limit
If the burner flames are not properly drawn into the
heat exchanger, the flame rollout protection device will
open. Possible causes are restricted or blocked flue
passages, blocked or cracked heat exchanger, a failed
induced draft blower, or insufficient combustion air. The
rollout protection device is a manual reset limit located
on the burner bracket. The cause of the flame rollout
must be determined and corrected before resetting the
limit.
•
Check flame sensor
A drop in flame signal can be caused by nearly invisible
coating on the sensor. Remove the sensor and carefully
clean with steel wool.
•
Check wiring
Check wiring for opens/shorts and miswiring.
IMPORTANT: If you have to frequently reset your gas/
electric package unit, it means that a problem exists that
should be corrected. Contact a qualified servicer for
further information.
Pressure Switch Stuck Open (2 FLASH CODE)
A pressure switch stuck open can be caused by a faulty
pressure switch, loose or broken wires can be interpreted
as a open switch, check all wiring, a disconnected or
damaged hose, a blocked or restricted flue, or a faulty
induced draft blower. If the control senses an open
pressure switch during the pre-purge cycle, the induced
draft blower only will be energized.
If the pressure switch opens after ignition has begun the
gas valve is deenergized, the circulator blower heat off
cycle begins, and the induced draft blower remains on.
The diagnostic fault code is two flashes.
Pressure Switch Stuck Closed (3 FLASH CODE)
A stuck closed pressure switch can be caused by a faulty
pressure switch or shorted wires can be interpreted as a
closed switch, check all wiring. If the control encounters
a pressure switch stuck closed, the induced draft blower
remains off. The diagnostic LED code for this fault is three
(3) flashes.
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