L.B. White AD100 - Manual (Page 20)

Troubleshooting Instructions
READ THIS ENTIRE SECTION BEFORE
BEGINNING TO TROUBLESHOOT PROBLEMS.
The troubleshooting flow charts in this section provide
systematic procedures for isolating heater problems.
TEST EQUIPMENT REQUIRED
The following pieces of test equipment will be required to
troubleshoot this system with minimal time and effort.
• D i g i t a l M u l t i m e t e r - fo r m e a s u r i n g vo l t a g e a n d
resistance.
• Low Pressure Gauge - (L.B. White Part No. 00764) for
checking inlet and manifold pressures of the gas control
valve against dataplate rating.
INITIAL PREPARATION
■
Visually inspect heater for apparent damage.
■
Check all wiring for loose connections and worn
insulation.
Refer to the system operation sequence in this section to
gain an understanding as to how the heater operates.
Understanding the operation sequence of the ignition
module and related components is essential as it will relate
directly to problem solving provided by the flow charts.
The ignition control module is self-diagnostic. The red light
on the module will flash a specific pattern depending upon
the problem which is diagnosed. To effectively use the flow
charts, you must first identify what the problem is by the
flashing pattern of the L.E.D. (light emitting diode)
diagnostic light. If the light is flashing, the flash pattern will
be followed by a pause and then a repeat of the flash
pattern until the problem is corrected.
Problems Page
L.E.D. Diagnostic light not on
during a call for heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
L.E.D. diagnostic light flashing:
A. Long Flash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
B. One Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
C. Two Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
D. Three Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
E. Four Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
F.
Five Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Components should be replaced only after each step has
been completed and replacement is suggested in the flow
chart. Refer to the Servicing sections as necessary to
obtain information on disassembly and replacement
procedures of the component once the problem is identified
by the flow chart.
SPARK IGNITION OPERATION SEQUENCE:
— Line voltage is sent to transformer and to ignition
control
— 24 V.A.C. is sent from transformer to the thermostat
— A call for heat occurs
— Thermostat returns 24 VAC to ignition control
— Red light on ignition control is illuminated
— Ignition control module performs an internal safe start
check
-- Internal components are tested
-- Voltage is sent to flame sensor from ignition
control to start flame proving process.
-- Air proving switch receives 24 volts from ignition
control.
— Ignition control module begins safety lockout timing
— Ignition control module starts fan motor for prepurge
-- Air proving switch is checked for proper operation.
-- Air proving switch closes and 24 volts is returned
to ignition control.
— Ignition control powers the igniter and igniter sparks.
— Ignition control sends 24 volts to gas control through
high limit switch.
— Ignition occurs
-- Igniter continues to spark until flame proving
occurs.
-- Igniter spark is discontinued
-- Gas valve stays open
— Room warms to desiredtTemperature
-- Thermostat is satisfied
-- Heater shuts down
— Process begins again on a call for heat
MULTIPLE IGNITION TRIAL SEQUENCE
— First trial for ignition takes approximately 10 seconds
— Two more trials for ignition will occur
-- Second and third trial follow immediately if first
trial fails
— Module star ts a 15 Minute “Wait” period to allow
ignition interruption to pass
— Ignition control repeats 3 ignition attempts after 15
minute waitpPeriod
— If ignition control module does not prove flame after third
trial, the module goes into safety lockout (3 Flash Pattern)
-- Igniter shuts down
-- Fan motor stops
-- Gas valve closes
To Reset the Ignition System
-- Unplug the heater and plug it back in
-- OR --
-- Turn the thermostat to “Off” or “No Heat” and then
back to above room temperature
WARNING
Electrical Shock and Burn Hazard
■
Do not attempt to service or repair this heater unless
you are a properly trained and qualified gas heater
service person.
■
Troubleshooting this system may require operating the
unit with line voltage present and gas on. Use extreme
caution when working on the heater.
■
Failure to follow this warning may result in property
damage, personal injury or death.
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