Control Board Replacement; Harvest Control - Thermistor - Hoshizaki KMS-1230MLH Service Manual

5. Control Board Replacement

The application switch located between relay X3 & X4 must be set to match the original
board application. Place this switch in the ALP position if there is no white wire supplied
to the K1 connector. If there is a white wire, place the switch in the C position. If this
switch is placed in the wrong position either the compressor contactor will remain
energized with the control switch OFF or the unit will not start.
The dip switches should be adjusted to the factory default settings as outlined in this
manual. S4 dip switch #8 must remain in the OFF position.
D. Harvest Control – Thermistor
A thermistor (semiconductor) is used for a harvest control sensor. The resistance varies
depending on the suction line temperatures. The thermistor detects the temperature of
the evaporator outlet to start the harvest timer. No adjustment is required. If necessary,
check for resistance between thermistor leads, and visually check the thermistor
mounting, located on the suction line next to the evaporator outlet.
Temperature (°F)
Check a thermistor for resistance by using the following procedure:
1) Disconnect the connector K3 on the board.
) Remove the thermistor. See "V.C.6. Removal and Replacement of Thermistor."
3) Immerse the thermistor sensor portion in a glass containing ice and water for  or 3
minutes.
4) Check for a resistance between thermistor leads. Normal reading is within 3.5 to 7 kΩ.
Replace the thermistor if it exceeds the normal reading.
Temperature (°C)
0 -18
10 -1
3 0
50 10
70 1
90 3
1
Resistance (kΩ)
14.401
10.613
6.000
3.871
.474
1.633