Troubleshooting HD Direct Spark Units
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Literature:6-586.0
Original: 10/5/15
evisions: NA
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Troubleshooting HD Direct Spark Units
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TABLE OF CONTENTS
– Definitions and Basic Oper ation
– Call for heat and units does nothing - Green Light ON
– Call for heat and units does nothing - Green Light OFF
– T roubleshooting Codes for Ignition Control
– Unit starts but does flame does not ignite
– Flame lights and shuts down within 10 seconds
– Main fan / air mover does not operate
– Replace control board O NLY after completing these steps
– FOR ADDITIONAL HELP & LIVE OPERATORS
DEFINITIONS & BASIC OPERATION
• Soft Lockout of Control - The control does not initiate a call for heat or
call for continuous f an while in lockout. The control will respond to an
open limit and undesired flame. Lockout shall automatically reset af ter 1
hour. Lockout may be manually reset by removing power from the
control for more than 1 second or removing the thermostat call for heat
for more than 1 and less than 20 seconds.
• Hard Lockout - If the control detects a f ault on the control board, t he
status LED will be de-energized and the control will lockout as long as
the fault remains. A hard lockout will automatically reset if the hardware
fault clears.
• Flame Status LED (Yellow LED labeled “FLAME”) is
provided to indicate flame status
• Call for Heating Sequence of Operation
• End of Call for Heating Sequence of Operation
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FLAME STATUS - YELLOW LED LABELED “FLAME”
• Flame Status LED is Lit - When flame is sensed, the
flame LED is lit.
• Flame LED flashes slowly - Flame current is below
1.0 uA (+/-50%), the to indicate “weak” flame.
• Flame LED flashes fast - Flame is present with
gas valve off. If flame is sensed l onger than 4
secs while the gas v al v e is de-energized, the
control shall energize the power exhauster
and indoor blower motor. When flame is no
longer sensed, the power exhauster will run
through post-purge and the blower motor will
run through fan off delay time. The control
will do a soft lockout, but will still respond to
open limit and flame. The Flame LED shall
flash rapidly when lockout is due to undesired
flame.
Yellow Flame LED
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HEATING SEQUENCE OF OPERATION
• Call for heat
• T stat contact close T stat on terminals R & W of board
• 24 volts from R to W terminal on board
• Power exhauster cycles on. 115 VAC at IND and Neutral on board.
• Starts pre purge cy cl e
• 24 volts through limits and pressure switch from board
• Short delay and then 24 volts to gas valve from board
• Igniter sparks
• Flames carries to sensing probe and proves
• Yellow light turns on, burner stays lit.
• 50 to 60 seconds later, fan motor cycles on.
• 115 volts at EAC and Neutral terminals.
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END OF HEATING SEQUENCE OF OPERATION
• Call for heat ends
• Thermostat contacts open
• Burner flame off
• Yellow light turns off.
• Post purge on power exhauster
• Power exhauster cycles off.
• Fan motor cycles off.
•
Green light on board sta ys on.
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CALL FOR HEAT – UNIT DOES NOTHING
• Green Light on Control Boar d is ON
– Verify that the thermostat is wired correctly & there
is a call for heat
– Thermostat should be wired between R & W
– If the thermostat is wired correctly and the unit still
does not operate. Turn power off. Remove tstat
wires. Carefully install a jumper wire between
terminals R & W directly on the control board. Turn
power on. BE AWARE THAT THE UNIT MAY START!
– Did installing the jumper wire resolve the issue?
Yes No
Back Start Over
CALL FOR HEAT – UNIT DOES NOTHING
• Green Light on Control Board is ON. Unit operates
correctly when a jumper wire is installed between
terminals R & W on the board
– Check field wiring to the thermostat
– Potentially a bad thermostat (verify and replace if
needed)
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CALL FOR HEAT – UNIT DOES NOTHING
• Green Light on Control Board is ON. Unit DOES
NOT operate correctly when a jumper wire is
installed between terminals R & W on the board
– Check for loose connections. Disconnect and
reconnect all Molex plugs.
– Check to make sure there are NO troubleshooti ng
codes
– Turn the switch to the gas valve off and on. Then
leave on
– Potentially a bad control board (verify and replace if
needed)
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CALL FOR HEAT – UNIT DOES NOTHING
• Green Light on Control Board is OFF
– There will not be a flash code
– Is there 24 VAC bet ween Sec & Com
on board?
Green Light
Yes
No
Sec & Com Terminals
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CALL FOR HEAT – UNIT DOES NOTHING
• Green Light on Control Board is OFF. 24 VAC NOT
present between Sec & Com on board
Possible Causes
Check for loose connections
Check incoming power (115 VAC)
If incoming power is correct, check for 24VAC at
the secondary of the transformer. If incoming
voltage is correct and no voltage at the secondary,
replace transformer
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CALL FOR HEAT – UNIT DOES NOTHING
• Green Light on Control Board is OFF 24 VAC IS
present between Sec & Com on board
Possible Causes
-Check fuse for blown element.
Remove the fuse. Check for continuity.
Do NOT just inspect element. Check for
continuity. If the fuse is bad, replace fuse.
-Check for loose connections
-If fuse is not blown, terminal board is not letting
24 VAC through the board. Replace board.
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TROUBLESHOOTING FLASH CODES
• No Flashes See Green Light is off
• One Flash Pressure swi tch does not close within
30 seconds of inducer energized.
• Two Flashes Pressure switch is closed before
inducer is energized
• Three Flashes Open in the safety switch circuit
(limit switch or flame roll out switch is open)
• Four, Five, Six or Seven Flashes
Back Start Over
Back Start Over
TROUBLESHOOTING FLASH CODES
• Four Flashes In lockout from failed ignition
or flame loss
• Five Flashes Twi n communic a ti ons fault
• Six Flashes Open in the safety switch circuit
5 times during heat cycle (limit switch or
flame roll out switch)
• Seven Flashes 5 Flame losses during one
heat cycle
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Back Start Over
NO FLASHES – TROUBLESHOOTING CODES
• No Flashes Go To:
Call for heat – unit does nothing
Back Start Over
ONE FLASH - TROUBLESHOOTING CODES
• Does the power exhauster cycle on?
Yes No
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ONE FLASH – NO POWER EXHAUSTER
• Pressure switch does not close within 30 seconds of inducer energized
• Unit sequence:
• Green Light on, call for heat, 24 volts at R & W on
board. Nothing happens. Green light will give One
flash. Fan motor will not cycle on.
• Possible cause:
• Defective exhauster mot or. Receiving 115 volts from
IND and NEUTRAL terminals on board, but will not
run. Replace exhauster .
• Defective board. Not sending 115 volts from IND and
NEUTRAL terminals to exhauster. Replace board
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ONE FLASH – PRESSURE SWITCH W ON’T CLOSE
• Pressure switch does not close within 30 seconds of inducer energized
• Unit sequence: Green light on, call for heat, 24 VAC at
R & W , power exhauster cycles on, after approx. 30
seconds, Green Light will give One Flash
• Possible cause:
• Blockage in tubing to pressure or venting not allowing
for a proper vacuum to pull pressure switch contacts
closed. Troubleshoot Venting.
• Wire off pressure switch
• 24 VAC not coming from board.
• Defective pressure sw i tch (verify and replace)
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TWO FLASHES - TROUBLESHOOTING CODES
• Pressure switch is closed before inducer is energized
• Unit Sequence: Green light on, call for heat, 24 volts
at R & W terminal. Nothing will happen to unit
operation except Green Light will give Two Flashes.
• Possible Cause:
• Defective or damaged pressure switch
• Showing continuity between terminals in non-heat
mode
• The two yellow wires are showing continuity in non-
heat mode.
• Defective board (verify and replace if bad)
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THREE FLASHES - TROUBLESHOOTING CODES
• Open in the safety switch circuit (limit switch or flame roll out
switch is open)
• The limit switch is ignored unless a call for heat is present (R to
W energized). If the limit switch is open and a call for heat is
present, the control de-energizes the gas valve, runs the blower
motor, and runs the power exhauster. The control will flash “3”
on the LED until the limit switch closes. When the switch recloses or the call for heat is lost, the control runs the power
exhauster through post-purge and runs the blower through the
fan off delay. The control will return to normal operation after the
blower off delay is completed.
• Possible Causes
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THREE FLASHES - TROUBLESHOOTING CODES
• Open in the safety switch circuit (limit switch or flame roll out
switch is open).
• Unit sequence:
• Green Light on, call for heat. Power exhauster cycles on.
• Fan Motor Cycles on. Green light starts three flashes.
• Possible cause:
• Open or short in safety circuit (flame roll out s witches som e and
some limit switches are man ual reset).
– Check for open contacts on switch in safety circuit. Reset flame roll
out switches and manual reset limit switches
– Check wiring. Wire off limit or flam e rollout switch. Limit or flame
rollout switch shorting to unit. Defec tive limit or flame rollout switch.
Verify and replace if required.
• Defective board, not letting 24 VAC through limits.
Back Start Over
FOUR FLASHES - TROUBLESHOOTING CODES
• In lockout fr om failed ignition or f lame loss
• Does the unit ignition spa rk
Yes No
Back Start Over
FOUR FLASHES - TROUBLESHOOTING CODES
• In lockout fr om failed ignition or f lame loss
unit DOES SPARK
• Does the flame shut down wit hin 10
Seconds
Yes No
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FOUR FLASHES - TROUBLESHOOTING CODES
• In lockout from failed ignition or flame loss unit
SPARKS and SHUTS DOWN within 10 seconds
• Unit Sequence:
• Green Light on, call for heat
• Power exhauster cycles on, starts pre purge
• 24 VAC present through pressure switch, limits, and to
gas valve
• Igniter sparks, burner cycles on for 10 seconds, then
cycles off, no yellow flame light on board. Fan motor
never cycles on.
• Possible Causes
Back Start Over
FOUR FLASHES - TROUBLESHOOTING CODES
• In lockout from failed ignition or flame loss unit
SPARKS and SHUTS DOWN within 10 seconds
• Possible Causes:
• Reversed Polarity
• Wire off sensor. Check for loose wires
• Dirty or defective flame sensor, not sending micro-
amps to board. Clean sensor with emery cloth. If the
problem is not resolved, verify and replace sensor.
• Defective board, getting correct micro-amps from
sensor, but not allowing ignition
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FOUR FLASHES - TROUBLESHOOTING CODES
• In lockout fr om failed ignition or flame loss unit
SPARKS and SHUTS DOWN within 10 seconds
• Reversed Polarity
• To check for reversed polarity. (1) Shut down all power
to unit (2) Switch main incoming power lines (black and
white) to unit. (3) Carefully turn main power back on to
unit.
• If issue is not resolved, shut off all power and return
white and black wires to original positions.
• More possible causes
Back Start Over
FOUR FLASHES - TROUBLESHOOTING CODES
• In lockout fr om failed ignition or flame loss unit
SPARKS and SHUTS DOWN within 10 seconds
• Have eliminated Reversed Polarity
• Wire off sensor. Check for loose wires
• Dirty or defective flame sensor, not sending micro-amps
to board. Clean sensor with emery cloth. If the problem
is not resolved, verify and replace sensor.
• If issue is not resolved, shut off all power and return
white and black wires to original positions.
• Potentially defective board.
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FOUR FLASHES - TROUBLESHOOTING CODES
• In lockout from failed ignition or flame loss unit
SPARKS but DOES NOT IGNITE
• Unit Sequence:
• Green light on: call for heat, 24 VAC at R & W terminals
• Power exhauster cycles on, start pre purge. 24 VAC
through pressure switch and limits.
• Igniter sparks, no ignition, no y ellow flame sense light.
Will cycle 5 times in this manner, then Green light will
flash four times. Power exhauster will cycle off. Fan
motor will never cycle on.
• Possible Causes
Back Start Over
FOUR FLASHES - TROUBLESHOOTING CODES
• In lockout from failed ignition or flame loss unit
SPARKS but DOES NOT IGNITE
• Possible Causes:
• Gas valve in “off” position
• No 24 VAC from board to gas valve
• Loose wires: wire off gas valve
• Excessive Inlet pressure
• Low or No gas pressure to inlet of valve (purge lines)
• Defective Gas valve. Verify and replace of required
• Defective board not allowing ignition
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FOUR FLASHES - TROUBLESHOOTING CODES
• In lockout fr om failed ignition or f lame loss
unit DOES NOT SPARK
• Unit Sequence:
• Green Light on, call for heat
• Power exhauster cycles on, starts pre purge
• 24 VAC power present through pressure switch, limits, and to valve
• No spark at igniter, RAW gas is going through orifices for approx. 6
seconds during this cycle, then cycles off, no yellow flame sense light
• Will cycle 5 times in this manner . T hen Green light will give four
flashes. Power exhauster will cycle off. Fan motor does not turn on.
• Possible Causes
Back Start Over
FOUR FLASHES - TROUBLESHOOTING CODES
• In lockout fr om failed ignition or flame loss
unit DOES NOT SPARK
• Possible Causes:
• Loose wires: Wire off Igniter
• Defective or damaged igniter. Examine, verify
and replace of required.
• Defective board not sending v olt age to i gnite r
Back Start Over
FIVE FLASHES - TROUBLESHO OTING CODES
• Twin c ommunications fault
• Occurs if the 24 VAC supply to the twins are not in phase with each
other, or power is removed from one of the twins.
• While a Twin Fault exists, the control does not respond to
thermostat commands and f lashes " 5" on the status LED. Open
limit and undesired flame response are still operational. The
control continually tries to establish communication and
automatically resumes normal operation when communication is
re-established. If a twin f ault occurs during a heat cycle, bot h
furnaces terminate t he call for heat imm ediately. The only chance
for blower mis-synchronization i s if the blower off delays are set
differently on the t wins. If a twin fault occurs during high speed fan
or continuous fan, both controls shut blowers off immediately.
Back Start Over
SIX FLASHES - TROUBLESHOO TING CODES
• Open in the safety switch circuit 5 times
during heat cycle (limit switch or flame roll
out switch). Control goes into a hard lockout.
• Lockout may be manually reset by removing
power from the control for more tha n 1
second or removing the thermostat call for
heat for more than 1 and less than 20 seconds
• Does the fan (main air mover) cycle on?
Yes No
Back Start Over
SIX FLASHES - TROUBLESHOO TING CODES
• Open in the safety switch circuit (limit switch or flame
roll out switch is open). Main air mover CYCLES ON.
• Unit sequence:
• Green Light on, call for heat. Power exhauster cycles on.
• Fan Motor Cycles on. Green light starts six flashes.
• Possible cause:
• Open contacts due to over-firing of unit (flame roll out switches
some and some limit switches are m anual reset).
– Check gas pressure. Check to make sure noth i ng is blocking airflow
out of unit.
– Wire off limit or flame rollout switch. Limit or flame rollout switch
shorting to unit. De f e ctive limit or flame rollout switch.
• Defective board, not letting 24 VAC through limits.
Back Start Over
SIX FLASHES - TROUBLESHOO TING CODES
• Open in the safety switch circuit (limit switch or flame roll out
switch is open). Main air mover DOES NOT cycle on.
• Unit Sequence:
• Green Light on, call for heat Power exhauster cycles on, pre purge
• 24 volts power present through pressure switch, limits, and to valve
• Igniter Sparks, burner cycles on, yellow flame light on board is on.
• After 3 to 4 mi nutes , unit goes out on a limit switch, yellow light off,
green light will flash six times.
• Possible cause:
• Check all wiring, loose wire
• Defective motor, 115 VAC present at EAC & Neutral terminals on
board, but motor does not run.
• Defective board, 115 VAC not present at EAC and Neutral terminals
Back Start Over
SEVEN FLASHES - TROUBLESHOOTI NG CODES
• 5 Flame losses during one heat cycle
• Ignition Re-Cycle - The c ontr ol wil l re-cycle
up to 5 flame losses (4 re-cycles) within a
single call for heat before going to lockout.
The LED will flash “ 7” during this lock out.
Back Start Over
BEFORE REPLACING THE CONTROL BOARD
• Remove thermostat and use a temporary jumper wire to make a call for heat
• Check the supply power for correct polarity
• Rech eck all wiring to the control boa r d for loose connecti ons. Disconnect and reconnect all Molex plugs
• Rech eck that the wiring to the contr ol boa r d matc hes the wiring diagr a m
• If the control board has a fuse, remove and test continuity of the fuse. Do not just do a visual inspection
of the fuse - check continuity
• Make sure the pressure switch is not opening during the call for heat cycle
• Check limits and rollout switches for an open circuit
• Turn the switch on the gas valve to off and then to on several times
• Make sure power inducer is running when there is a call for heat
• Check for a proper micro amp signal from the flame sensor to the control board. A proper signal is 1-5
micro-amps
• Check for proper supply gas pressure. Excessive gas pressure can/will lockup the main valve
• Check for limit and/or flame sensor shorts (make sure they are not touching metal)
• Check for any moisture on board that may have occurred if checking for gas leaks with a liquid solution.
• Check in-line regulators for BTU sizing, and lock up point not above a 14” WC.
• Check setting of heat anticipator of t stat if applicable, and wire size and run
• Rev iew troubleshooting codes.
• Check for any moisture or moisture marks on the board that may have occurred if checking for gas leaks
with liquid solution.
• Check in-line regulators for BTU sizing and lock up point not above a 14" WC
• Check to make sure external regulator is not right next to the unit so that the regulator "fights" the
• regulator inside the combination gas valve.
• Check setting of heat anticipator of T -Stat if applicable, also check wire size and run length
Back Start Over
FOR ADDITIONAL HELP
INSTALLATION & SERVICE MANUAL
LIVE OPERATORS
HD Installation and Service Manual
Other Installation & Service Manuals
Live Operators: 800-828-4328
Back Start Over
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