Technicians Only Freeze Cycle Sequence

CME1356R and CME1656R

Technicians Only: Freeze Cycle Sequence

Assuming the machine has been operational, the Freeze cycle begins with the end of the Harvest Cycle:

Water Inlet Valve is Closed

Water Pump is ON

Compressor is ON

Hot Gas Valve is Open

AutoIQ Controller Operation, Beginning freeze:

1.Switches on Freeze indicator light and shuts off the hot gas valve.

2.Opens the water valve to top off the reservoir. The controller checks that water fills the reservoir, if it does not fill up within 250 seconds, the controller shuts the machine down. It will automatically try to restart in 20 minutes.

3.Measures and stores the discharge temperature.

4.If the discharge temperature exceeds the design maximum, shuts the machine down on a Refrigeration Error.

5.Checks for a “bin full" signal throughout the cycle.

6.Measures the reservoir water temperature. If the machine is operating correctly, the reservoir water temperature will fall at a standard rate. The AutoIQ Controller will be checking to see if the water temperature fall matches that rate.

If not, it re-checks the discharge line temperature. If too low, it Shuts Down on a Refrigeration Error. If the discharge temperature is acceptable, the water system is checked by shutting off the water pump and determining if the water level goes up enough. If it does not, the inlet water valve will open again to fill it. If, after restarting, the water level does not drop, it is assumed that there is a water pump problem and the machine Shuts Down on a Water Error.

If the water level does “measure up" the water pump is restarted and the AutoIQ Controller then measures how long it takes to lower the water level. If the water level does not fall, the machine Shuts Down on a Water Error.

7.Once per freeze cycle the machine will shut off the water pump. It only does this when the water temperature reaches a preset minimum. The pump will only be off for a few seconds.

8.As the machine makes ice, the water level in the reservoir will ultimately fall to the Harvest Level. The first time that happens per freeze cycle the inlet water valve is re-opened and the reservoir is refilled. The next time it happens, the unit will go into a harvest cycle.

Note: If the freeze cycle exceeds the preset Maximum (36 minutes), the Controller will Shut Down the machine and switch on the Refrigeration Light.

9.The end of Freeze cycle will see the machine in this state:

Water level = below harvest position

Water inlet valve will be off

Water pump will be ON

Compressor will be ON

Hot gas valve will be off

At this point Harvest begins and the AutoIQ Controller switches the Harvest indicator light ON.

Restarts:

If the machine is restarting after it has shut off because the bin was full, the first freeze cycle sequence is like this:

1.Purge valve is open.

2.Pump starts.

3.Purge valve closes.

4.Water valve opens to fill the reservoir.

5.Compressor starts.

Note: If there is a power interruption, after power is restored the machine will restart, go thru a brief Freeze cycle and go thru a 6 minute Harvest cycle. Error Restarts:

The machine automatically attempts to restart 50 minutes after a shut down. If another problem occurs in the next cycle, the machine will attempt one more restart. If another problem occurs in the next cycle, the machine will shut off and must be manually reset.

May 2001

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