SERVICE PROCEDURE D24-I
Thermostat Circuit Testing
CAUTION
Be Careful When Making Voltage
Measurements or Jumping Terminals
Not to Damage orDeform Connectors or
Connector Pins.
DANGER
120 volt exposure. To avoid personal injury,
use caution while performing this procedure.
WARNING!
Do not reset the display from the hard lockout
state without correcting the cause of the
overheating condition.
Check continuity of wire harness to affected sensor. Measurement
of ohmeter should be close to 0 ohms. Replace wire harness if high
resistance ismeasured (over 0.5 ohms) Check wires for intermittent
connections,shorts, frayed insulation. Replace if necessary
(see photo 8)
Turn power on to water heater.
Run water heater through heating cycle and verify proper operat ion.
Sensor temperature can beviewed whenburner shuts off(see
section on viewing the di splay in “Service Mode”.
This procedure assumes the flue damper is in working order. Be sure damper opens unde r its own power when the
thermostat circuit is by-passed. Damper must be open or removed during this test. Do not force damper open using your
hands or tools.
Turn power “OFF”.
Draw water to cooltank below 120 deg. F
Check lower sensor. Is the sensor fully inserted into the well?
Sensor isheld in place witha clip fastened to the well (see photo 9)
Check lower sensor wire making sure it is n ot damaged or has
breaks in the wire insulat ion. Check upper h arness wires to upp er
sensor, if used(somemodels).
If sensor clipis damaged
replace clip. Replace lo wer
sensor if damaged.
Check Sensor Resistance
(see “Sensor Resistance
Testing” section & phot o 7)
Y
N
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Measuring upper
sensor resistance
through wire
harness
(disconnected at
control board).
Checking
continuity of
upper sensor wire
harness.
Removing lower
sensor fromwell.
Heldin place by a
clip fastened to
well shoulder.
Condition: Water Heater Not Operating
Display shows error code “65”
High Water Temperature (over 200 deg. F)
Ifwire harness checks out O.K.check resistanceof sensor. Refer to
section onSensor ResistanceTesting. If sensor resistance is not
near the values shownin thetable, then replace upperor lower
sensor asindicated byerror code number.
Unplug or disconnect electricalpower to the water heater
Condition: Water Heater Not Operating
Display shows error code “31” (Upper Sensor
Readings Faulty) or error code “32” (Lower Sensor
Readings Faulty)
See next page
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8
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