Checking Flame Sensor - Daikin DCG Series Service Instructions Manual

SERVICING
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
A pressure switch stuck open can be caused by a faulty
pressure 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 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 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
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.
diagnostic 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.
Flame Detected with Gas Valve Closed (5 FLASH CODE)
If flame is detected with the gas valve deenergized, the
combustion and air circulator blowers are energized. The
diagnostic fault code is five (5) flashes for this condition. The
control can be reset by removing the power supply to the unit
or it will automatically reset after one hour. Miswiring is the
probable cause for this fault.
A O - C
BNORMAL PERATION
Short Cycle Compressor Delay (6 FLASH CODE)
The automatic ignition control has a built-in feature that
prevents damage to the compressor in short cycling situa-
tions. In the event of intermittent power losses or intermittent
thermostat operation, the ignition control will delay output to
the compressor contactor for three minutes from the time
power is restored. (Compressor is off a total of three
minutes). The diagnostic LED will flash six (6) times to
indicate the compressor contactor output is being delayed.
(2 FLASH CODE)
(4 FLASH CODE)
C
OOLING ODES
NOTE: Some electronic thermostats also have a built-in
compressor short cycle timer that may be longer than the
three minute delay given above. If you are using an
electronic thermostat and the compressor has not started
after three minutes, wait an additional five minutes to allow
the thermostat to complete its short cycle delay time.
S-314 CHECKING FLAME SENSOR
A flame sensing device is used in conjunction with the
ignition control module to prove combustion. If a microamp
signal is not present the control will de-energize the gas valve
and "retry" for ignition or lockout.
DSI Direct Spark Ignition Systems
HIGH VOLTAGE!
Disconnect ALL power before servicing
or installing this unit. Multiple power
sources may be present. Failure to do so
may cause property damage, personal injury
or death.
1. Disconnect the flame sensor wire from terminal FS of the
ignition control module.
The
2. Connect a microamp meter in series with this wire and
terminal FS.
3. Be sure the negative side of the meter is to the wire and
the positive of the meter is to terminal FS.
4. Turn on Power.
Flame
Sensor
Flame Sensor
71