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68-0063—3 14
L8104A,B,C,D
TROUBLESHOOTING
CHECK TRANSFORMER, 120V SUPPLY,
CORRECT AS NECESSARY.
IGNITION MODULE WAS IN LOCKOUT.
OBSERVE FOR 2-3 CYCLES TO MAKE
SURE SYSTEM IS OTHERWISE OK.
NO
YES
CHECK VOLTAGE AT 24V TERMINALS
OF ELECTRONIC CONTROL MODULE.
IS THIS AN ELECTRONIC IGNITION
SYSTEM WITH 100 PERCENT LOCKOUT?
DISCONNECT 24V POWER AT IGNITION
MODULE AND RECONNECT AFTER
ABOUT 1 MIN. SET POTENTIOMETER TO
MAX TEMPERATURE SETTING.
YES
NO NO
YES
IS VOLTAGE BETWEEN 21.5 AND
28.5 VAC?
DOES HEATER TURN ON?
IS LED LIT?
SYSTEM SHUT DOWN DUE TO ECO
OPENING.
DEPRESS AND RELEASE MANUAL
RESET BUTTON.
DOES LED TURN OFF?
SYSTEM RESET.
YES
DISCONNECT ECO LEADS AND MEASURE
RESISTANCE WITH OHMMETER.
IS RESISTANCE GREATER THAN 100K
OHMS WITH WATER TEMPERATURE LESS
THAN 180°F?
REPLACE SENSING BULB WITH
ECO SWITCH.
YES
REPLACE ELECTRONIC CONTROL MODULE.
RECONNECT ALL LEADS AND CHECK OUT
SYSTEM.
YES
NO
NO
NO
REFER TO TROUBLESHOOTING IF
WATER IS TOO HOT.
SENSOR(S) MAY BE SHORTED OR
OPEN. CHECK FOR LOOSE, BROKEN
OR SHORTED WIRES. REPLACE
SENSING BULB(S) IF NECESSARY.
REPLACE ELECTRONIC CONTROL
MODULE. RECONNECT ALL LEADS
AND CHECK OUT SYSTEM.
REPLACE POTENTIOMETER.
RECONNECT ALL LEADS AND CHECK
OUT SYSTEM.
REPLACE SENSING BULB WITH ECO
SWITCH.
NO
YES
DISCONNECT ECO LEADS AND MEASURE
RESISTANCE WITH OHMMETER.
DISCONNECT SENSOR LEADS FROM
ELECTRONIC CONTROL MODULE AND
MEASURE RESISTANCE OF SENSOR(S)
WITH OHMMETER.
SENSORS OK. IS THE POTENTIOMETER
REMOTE?
DISCONNECT POTENTIOMETER LEADS FROM
ELECTRONIC CONTROL MODULE. MEASURE
RESISTANCE OF POTENTIOMETER WITH
OHMMETER.
POTENTIOMETER OK. REPLACE ELECTRONIC
CONTROL MODULE. RECONNECT ALL LEADS
AND CHECK OUT SYSTEM.
NO
YES
YES
YES
NO
NO
M416A
IS RESISTANCE GREATER THAN
100K OHMS (OPEN)?
IS RESISTANCE BETWEEN 700K AND 30K
OHMS (SEE TABLE 1)?
IS RESISTANCE GREATER THAN 500 OHMS AT
MINIMUM TEMPERATURE SETTING AND LESS
THAN 100 OHMS AT MAXIMUM TEMPERATURE
SETTING (CHECKS FOR OPEN OR SHORTS)?
L8104C, D