SERVICING
49
TROUBLESHOOTING
Ignition Control Error Codes
The following presents probable causes of questionable unit
operation. Refer to
Diagnostic Indicator Chart
for an inter-
pretation 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 estab-
lished 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 igni-
tion 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 re-
set 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 in
-
visible 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 pres-
sure switch, faulty 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 ener-
gized. 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 faulty 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.
Open Thermal Protection Device
(
4 FLASH CODE)
If the primary limit switch opens, the gas valve is immediately
deenergized, the induced draft and air circulating blowers
are energized. The induced draft and air circulator blowers
remain energized until the limit switch recloses. The diag-
nostic fault code for an open limit is four (4) flashes.
A primary limit will open due to excessive supply air tempera-
tures. This can be caused by a dirty filter, excessive duct
static, insufficient air flow, or a faulty limit. Check filters, total
external duct static, blower motor, blower motor speed tap
(see wiring diagram), and limit. This limit will automatically
reset once the temperature falls below a preset level.
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