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If water temperature is too cold or heater does not come on, proceed as follows:
START
CHECK VOLTAGE AT 24V TERMINALS
OF ELECTRONIC CONTROL MODULE.
IS VOLTAGE BETWEEN 21.5 AND
28.5 VAC?
YES
IS THIS AN ELECTRONIC IGNITION
SYSTEM WITH 100 PERCENT LOCKOUT?
YES
DISCONNECT 24V POWER AT IGNITION
MODULE AND RECONNECT AFTER
ABOUT 1 MIN. SET POTENTIOMETER TO
MAX TEMPERATURE SETTING.
DOES HEATER TURN ON?
NO
DISCONNECT ECO LEADS AND MEASURE
RESISTANCE WITH OHMMETER.
IS RESISTANCE GREATER THAN
100K OHMS (OPEN)?
NO
DISCONNECT SENSOR LEADS FROM
ELECTRONIC CONTROL MODULE AND
MEASURE RESISTANCE OF SENSOR(S)
WITH OHMMETER.
IS RESISTANCE BETWEEN 700 AND
30K OHMS (SEE TABLE 1)?
YES
SENSORS OK. IS THE POTENTIOMETER
REMOTE?
YES
DISCONNECT POTENTIOMETER LEADS FROM
ELECTRONIC CONTROL MODULE. MEASURE
RESISTANCE OF POTENTIOMETER WITH
OHMMETER.
IS RESISTANCE GREATER THAN 1000 OHMS AT
MINIMUM TEMPERATURE SETTING AND LESS
THAN 50 OHMS AT MAXIMUM TEMPERATURE
SETTING (CHECKS FOR OPEN OR SHORTS)?
YES
POTENTIOMETER OK. REPLACE ELECTRONIC
CONTROL MODULE. RECONNECT ALL LEADS
AND CHECK OUT SYSTEM.
L8104A, B
NO
YES
NO
YES
NO
NO
NO
CHECK TRANSFORMER, 120V SUPPLY,
CORRECT AS NECESSARY.
IGNITION MODULE WAS IN LOCKOUT.
OBSERVE FOR 2-3 CYCLES TO MAKE
SURE SYSTEM IS OTHERWISE OK.
REPLACE SENSING BULB WITH ECO
SWITCH AND OBSERVE SYSTEM IN
OPERATION. IF WATER HEATER DOES
NOT TURN OFF AFTER WATER
REACHES SET POINT TEMPERATURE,
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.
13
L8104A,B,C,D
TROUBLESHOOTING
M135B
68-0063—3
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