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When the machine is first powered on, it should purge some water then go into refrigeration. At that point you should hear the water pump start to circulate water over the evaporator and the compressor start and then the condenser fans will run when the condenser gets hot.  Verify that the pump is pumping and that the compressor is running. Check to make sure the float valve has shut off and not continuing to send water down the overflow. Or if the drain valve has stuck open. If you had low voltage for a extended period on time to the machine you may have damaged the compressor or the starting components. Now if all are running, feel the top line going into the evaporator. It should be cold and starting to freeze. If it is warm or hot, the hot gas valve is not closing. If the top line is cold, after a few minuets the bottom line should start to feel cool. That means the machine is trying to make ice.Â
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Check your control board LED’s. The green should be on, but is it flashing or solid? Unfortunately Maxx Ice does not use a feed back board to test thermistors. So in the early cycle if the LED is flashing, the thermistor for the evaporator is bad. Which sends the machine into early harvest. Now watch a clock and the LED’s. The machine will go solid green till the tail coil of the evaporator gets very cold. then it wiill flash to complete the ice making time. Now the yellow harvest will light, the pump stops, The hot gas bypass valve opens, and the fans stop.  This heats the evaporator till warm enough to drop the ice. Providing the machine is clean. The cycle then repeats till the bin full LED lights.
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The ice making process is in the manuals that I have included here;
https://download.partstown.com/is-bin/intershop.static/WFS/Reedy-PartsTown-Site/-/en_US/manuals/MXIC-MIM452_iom.pdf
https://download.partstown.com/is-bin/intershop.static/WFS/Reedy-PartsTown-Site/-/en_US/manuals/MXIC-MIM452_spm.pdf
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It sounds like the first tech had knowledge of the machine but was working from a warrenty standpoint for Maxx Ice. I would not trust the second one, as he should not have added refigerant till knowing what was wrong and it should have been removed and weighed. If he added because of low suction pressure, you may have a metering problem.