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See page F9 for adjustment procedure. Purge When the machine enters the harvest cycle the water pump continues to run and the purge valve opens. This allows mineral laden water to be pumped from the trough to the drain. This helps keep the water system clean. On dual evaporator models beginning March 1998, the water pump and purge valve remain energized during the entire harvest cycle. All other machines, the water pump and purge valve de-energize once water is flushed from the trough. The length of time that the water pump and purge valve remain energized is controlled by the cam switch, see page F6. Note: The purge valve must be completely closed during the freeze cycle. If water leaks through the purge valve during freeze the freeze time will be extended and poor ice formation will result. The purge valve can also be energized manually by pushing the purge switch. The purge switch is used when cleaning the water system to flush cleaning solution down the drain. See page B1 for cleaning instructions. UC20/EUC200 - Bin Removal The bin can be removed on under counter models to access many of the components. Procedure 1. Remove the 2 phillips head screws from rear of top panel. 2. Remove the louvered panel below the bin. 3. Remove 2 screws, from front comers of bin. 4. Remove 1 screw from center of front edge of bin. 5. Remove drain tube from underneath bin. This step is not necessary on machines manufactured before 5/88. D3 Notes IRiffterifom System I EC and ECP Series Refrigeration Cycle and Components Before diagnosing the refrigeration system, it is very important that refrigerant charge be correct. Whenever the refrigeration system has been opened, the filter-drier must be replaced and the proper refrigerant charge must be weighed in. See refrigerant charge information on page A3 through A8. Refrigerant Pressures At the beginning of the freeze cycle the suction pressures are as indicated in the chart below. The pressure at the beginning of freeze may be up to 10 p.s.i. (.7 bar) less then those stated, depending on operating conditions. Pressures less than this may indicate an under charge. With proper ice bridge thickness, the suction pressure at the end of the freeze cycle is also indicated in the chart below. This pressure may also vary with operating conditions. The head pressure on water cooled units should be adjusted to the pressures shown in the chart. Discharge pressure on air cooled units will vary with ambient conditions but will typically run higher than water cooled units. Remote condensers located in ambient temperatures below 70°F (21 °C) will typically run a lower head pressure. See Mixing Valve later in this section. Model Number Refrigerant Type Approx. Suction Pressure Begin Freeze End Freeze Approximate Head Pressure EUC200/EC206 R-134a 30 PSI (2.1 bar) 10 PSI (.7 bar) 125 PSI (8.6 bar) UC20, C20, C40 R-12 30 PSI (2.1 bar) 10 PSI (.7 bar) 125 PSI (8.6 bar) C40B1 R-502 50 PSI (3.4 bar) 34 PSI (2.3) 225 PSI (15.5 bar) C30,C50,C66 R-502 50 PSI (3.4 bar) 26 PSI (1.8 bar) 225 PSI (15.5 bar) All R404a machines R-404a 55 PSI (3.8 bar) 28 PSI (2 bar) 250 PSI (17.2 bar) Cl 06 R-22 50 PSI (3.4 bar) 24 PSI (1.7 bar) 225 PSI (15.5 bar) Note: The above information also applies to the 50Hz versions of the machines listed. El Rstterafoffn Syitsm I EC and ECP Series Refrigerant is pumped throughout the refrigeration system by a hermetic compressor. Refrigerant, in its gas state, is pumped from the compressor to the condenser. Heat is removed from the refrigerant either by forced air movement through the condenser or by a heat exchanger (water cooled condenser) that transfers heat from the refrigerant to water. The refrigerant changes to a liquid when cooled. The refrigerant in a liquid state passes through a filter drier. The filter drier traps small amounts of moisture and and foreign particles from the system. Important! The filter drier must be replaced whenever the refrigeration system is opened or if the refrigerant charge has been completely lost. Compressor The compressor runs during the entire cycle. If the valves in the compressor are damaged the compressor will be unable to pump refrigerant efficiently. Damaged valves may be the symptom of another problem in the refrigeration system such as liquid refrigerant returning to the compressor or high head pressure. When a compressor is replaced it is important that the refrigeration charge be weighed in and the system be checked for proper operation to prevent a repeat failure An inefficient compressor will usually have a higher than normal suction pressure at the end of the cycle. The freeze cycle will be longer then normal and/or the harvest cycle may be excessively long. To check the compressor, check the compressor amperage draw five minutes into the freeze cycle. If the amp draw is less then 70% of rated full load amps the compressor may he inefficient. These symptoms may also be caused by other problems...

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