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Scotsman MDT5N25 User Manual

Page 24

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Scotsman MTD3, MDT4, MDT5, MDT6
Service Diagnostic - Touch Free and Control System

The MDT controller operates the refrigeration and dispensing systems. The on/off of the ice making

system is determined by infrared sensors. Ice or water dispensing is also determined by infrared

sensors. Additionally there is a safety sensor, the water level sensor, that prevents operation if there

isn’t any water in the reservoir.

1. Confirm line voltage is being supplied to terminals 1 and 15.

2. No ice, No Water light is On, water in reservoir. This is typically caused by a dirty tip on the water

level sensor. If the tip is clean and undamaged, check for voltage at the Water Sensor pins, it

should read about 12 volts DC. If no voltage, replace the controller. If there is voltage, replace

the sensor. Another check is sensor resistance, the sensor normally reads about 850 ohms at 72

degrees F., higher if colder and lower if warmer. There is no bypass method or part that will allow

operation, only a good sensor will work.

3. Ice is not dispensed when a container is in front of the sensor. First try a non-clear container,

as the sensors infrared light can be absorbed by clear glass. Second, unplug the sensors at the

Dispense connection and jump the two outside pins. The ice dispense relay should engage and

supply power to the dispense motor. If it does not, replace the controller. If it does, replace the

sensors.

291-8

Line Voltage

Jump outside pins to

test ice dispense relay

12 volts DC

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