A.O. Smith Master-Fit 100 Series, Service Handbook

Page: 34 / 40

32
Servicing should only be performed by a Qualified Service Technician
TEST 11
–
WATER HEATER SHUTTING OFF BELOW SETTING
TEST 11
WATER HEATER SHUTTING OFF BELOW SETTING
(Water Temperature Circuit Check - Continuity)
IF......... THEN............
Continuity check pin to pin of lower
temperature probe shows 1 or 0
(E4)
See Test 4. Check wiring and plug connections to heater control
board receptacle E4.
Replace lower temperature probe.
Continuity check red wire pin to
red wire pin on upper temperature
sensor shows 1 or 0 (E3).
See Test 4. Check wiring and plug connections to heater control
board receptacle.
Replace upper temperature probe.
All above checks are okay. Check wiring and plug connections to heater control board
receptacle.
Replace upper temperature probe.
CONDITIONS:
• Main burner ignited.
• Stored water is below temperature setting more than 5° F (Tank Average).
• Power Off.
• Plug disconnected from heater control board receptacle E3 and E4.