Temperature Probe Short (Upper Or Lower); Temperature Probe - State Water Heaters SUF 119300 Service Handbook

8. TEMPERATURE PROBE SHORT (UPPER OR LOWER)

Upper Temp Probe (Short)
0 days 0 hrs 0 mins ago
Error Code: 45- 0
The indicated temperature Probe
may be shorted or open. Check
connector and resistance of
Probe.
CHECK/ REPAIR:
• Make sure connector is clean and tight.
• Check probe's resistance.
• Replace the Temperature Probe if shorted (resistance is below 390 Ohms). See Temperature Probe section
below.

TEMPERATURE PROBE

designed to protect against excessively high water temperatures inside the water heater's storage tank. The
ECO is a normally closed switch that opens on a rise in temperature. The ECO switch is located inside the
Temperature Probe (two red wires/Pins 2 & 3). See page 30 for pin layout. The ECO temperature setting is non
adjustable; the contacts open at approximately 201°F (94°C) and will close at approximately 140°F (60°C).
The Control System constantly monitors the state of the ECO switch contacts. If the ECO activates (contacts
open) due to abnormally high water temperature the Control System will lock out and display Energy Cut
Out (ECO) on the UIM.
Should the ECO activate, the water temperature must drop below 140°F (60°C) before the Control System
can be reset. Once the water temperature has cooled below this point the electrical circuit breaker that
serves the water heater must be turned off and on again to reset the Control System.
TEMPERATURE SENSOR
The Temperature Sensor located inside the Temperature Probe is a "thermistor" (two black wires/Pins 1 &
4). See page 30 for pin layout. Thermistors are thermally sensitive resistors. As the water temperature rises
the resistance (measured in ohms) of the sensor will decrease; as the temperature falls the resistance will
increase - see "Temperatures" Table on next page.
The Control System interprets changes in the temperature sensor resistance as changes in water temperature
and uses this data to activate and deactivate heating cycles and displays this temperature in the Control
System menus, see "(UIM) User Interface Module Screen" Figure on Page 51.
The Control System constantly monitors the Temperature Sensor. The Control System is programmed to
declare a fault condition if the resistance of the temperature sensor drops below 390 ohms (shorted) or above
56,000 ohms (open).
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BACK ADVANCED
Servicing should only be performed by a Qualified Service Technician
CAUSES:
• The Upper or Lower Temperature Probe appears
to be shorted (very low resistance). This fault code
often means the connector has been corroded by
cleaning chemicals or other substances.
This section of the Service Handbook provides information
on the Temperature Probe. The Upper Temperature Probe
contains the ECO (energy cut out) and a Temperature
Sensor. The Temperature Probe connects to the J9 Socket
on the CCB, see "CCB Circuit Board Layout" on Page 47
and "CCB Connection Identification" on Page 48.
ECO HIGH TEMPERATURE LIMIT SWITCH
The ECO (energy cut out) is a high temperature limit switch