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. Refer
to the Component Testing section of this Service Guide for
general instructions on performing voltage and continuity
checks as well as evaluation of specific components as
indicated by these charts. Refer to the wiring diagram for
assistance in performing voltage and continuity checks.
Refer to the Service section for gas pressure checks and
adjustments as indicated by the flow charts.
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.
IGNITION AND SAFETY CONTROL
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
Heater not cycling above minimum heat output . . . . . . . .21
L.E.D. Diagnostic light not on
during a call for heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
L.E.D. diagnostic light flashing:
A. Long Flash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
B. One Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
C. Two Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
D. Three Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
E. Four Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
F.
Five Times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
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.
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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Summary of Contents for GUARDIAN Smart Sense AD250
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