Hoshizaki KM-900MAF, KM-900MWF, KM-900MRF3 service manual Setting Time

1) Defrost Control

A thermistor (Semiconductor) is used for a defrost control sensor. The resistance var- ies depending on the Suction Line temperatures. The Thermistor detects the tempera- ture of the Evaporator outlet to start the Defrost 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)	Resistance (kΩ )
0	14.401
10	10.613
32	6.000
50	3.871
70	2.474
90	1.633

Check a thermistor for resistance by using the following procedures.

(i)Disconnect the connector K3 on the board.

(ii)Remove the Thermistor. See “V. 11. REMOVAL AND REPLACEMENT OF THER- MISTOR.”

(iii)Immerse the Thermistor sensor portion in a glass containing ice and water for 2 or 3 minutes.

(iv)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.

2) Defrost Timer

No adjustment is required under normal use, as the Defrost Timer is adjusted to the suitable position. However, if necessary when all the ice formed on the Evaporator does not fall into the bin in the harvest cycle, adjust the Defrost Timer to longer setting by adjusting the Dip Switch (No. 1 & 2) on the Controller Board.

SETTING			TIME
Dip Switch	Dip Switch
No. 1		No. 2
OFF		OFF	60 seconds
ON		OFF	90 seconds
OFF		ON	120 seconds
ON		ON	180 seconds

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