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11112014GW
Code 41 Troubleshooting Procedure
Freeze Protection Sensor for External Units
NOTE: If the KB water heater’s freeze protection sensor/thermistor is unplugged/cut/shorted, it will not
allow the water heater to fire up but will show a code 41.
If the VC water heater’s freeze protection sensor/thermistor is unplugged/cut/shorted, it will allow the
water heater to fire up. At which point it will flash a code 41 alternating between the code 41 and the
set point temperature
.
1.
Check sensor wiring harness for loose, broken or damaged connections from sensor back to PC
board.
2.
Ensure sensor is open to outside air and not covered with insulation.
3.
Check the resistance readings of this component using a volt/ohm meter capable of reading 20K
ohms. Set meter to proper setting for checking 20K ohms and insert meter leads into each end
of the sensor plug. Then apply heat to the sensor bulb. You will notice the sensor resistance
reading start to drop when heat is applied. A simple way to apply heat is to place the sensor
bulb between your thumb and another finger and apply pressure. The heat from your body will
cause the resistance reading to decrease. If the sensor reading starts to decrease with heat
applied normally that indicates the component is functioning properly. The resistance reading
will increase if ice is placed against the bulb. Typical resistance values are 11.4 – 14K ohms at 59
degrees ⁰F, 6.4 – 7.7K ohms at 86 ⁰F, 3.6 – 4.5K ohms at 113⁰F, 2.2 – 2.7K at 140 ⁰F or 0.6 – 0.8K
at 221 ⁰F.
If the outside air temperature thermistor (on outdoor models only) is open or disconnected the
unit will continue to operate and flash a code 41. The display will alternate between the set
point temperature and the code 41. Since the thermistor is used basically to activate the freeze
protection, there’s no need for it not to allow the unit to operate. Once the issue causing the
code is cleared the error code will disappear.
