CHAPTER IV SEC III CONT. ·  SEC IV · SEC.  V CONTROL  THERMOSTAT 2. WATER REGULATING VALVE The   water   regulating   valve   is   sensitive   to   water   line pressure.      Under   normal   conditions   adjustable   valves require   only   an   initial   adjustment.      Water   regulating valves of the self-adjusting type need no adjustment, but erratic  operation  may  be  found  when  water  pressures are sub-normal or above normal.  When water pressures exceed  80  PSI,  a  water  pressure  regulator  should  be installed in the water supply line ahead of the cooler and adjusted to 40 PSI. SECTION IV - FIELD REPLACEABLE PARTS The parts listed below should be field replaced. WATER REGULATING VALVE Turn  off  water  supply  and  relieve  the  water  pressure. Remove water regulating valve and replace.  Due to the variety  of  water  regulating  valve  s,  specific  instructions regarding  a  valve  can  be  had  on  request.    Please  give model,   style,   and   serial   number   information   found   on Model Plate with this request. STRAINER - DRAIN Unscrew or snap strainer from drain. CABINET TOP AND SIDE PANELS Remove and replace as explained in Chapter II, Section m. TEMPERATURE CONTROL The  controlling  thermostat  is  mounted  in  the  machinery compartment.  Disconnect the power supply and  detach  thermostat.    Remove  power  element  from bulb well on cooling unit. FAN AND MOTOR ASSEMBLY Turn    off    electrical    supply.        Remove    fan    and    motor 'assembly.    NOTE  -  Handle  fan  blade  with  care.    Mis- alignment can cause noise and/or motor failure. COMPRESSOR OVERLOAD PROTECTOR AND RELAY Disconnect    power    supply    and    remove    compressor terminal  cover.    Replace  relay  and  overload  with  exact factory replacement. COMPRESSOR CAPACITOR Remove and replace with factory replacement. CONDENSER WATER REGULATING VALVE Turn off water supply and replace with factory replacement unit. SECTION V - AUTHORIZED REPAIR STATION The hermetic refrigeration system of a cooler in warranty must  never  be  opened  in  the  field.    Such  repair  work should be done at an authorized repair station. If  warranty  has  expired,  the  components  of  the refrigeration   system      can   be   field   replaced.      Extreme care    has    to    be    taken    in    cleanliness,    dehydration, evacuation  and  charging  of  the  system.    Cleanliness  is most  important  in  servicing  the  system,  since  dirt  can contaminate   or   cause   a   restricted   flow   of   refrigerant through the system. Maximum care is maintained in the production of the cooler to assure a moisture level of 10 PPM or less. Moisture  cannot  be  tolerated  in  the  system,  since  it  has an   oxidizing   effect   on   the   refrigeration   parts   or   may freeze    the    capillary    exit    blocking    the    flow    of    the refrigerant. Precautions   are   also   taken   in   manufacture   to exclude air and non-condensibles from the system. The    system    is    swept    with    a    refrigerant    vapor    and evacuated to 250 microns. Charging of the system with refrigerant is critical. An  overcharge  causes  the  suction  line  to  frost  or  sweat and may cause damage to the compressor. The    service    man    attempting    to    service    the refrigeration  system  in  the  field  should  have  a  vacuum pump   capable   of   pumping   down   to   100   microns,   a vacuum        gauge    capable    of    reading    10    microns,   a Halogen  leak  detector  capable  of  sensing  a  refrigerant leak of 0.10 ounces per year, a charging system capable of   charging   within   0.      10   ounces   by   weight   and   a thorough knowledge of the refrigeration system. It  is  highly  recommended  therefore,  to  have  the cooler with an internal refrigeration defect repaired at an authorized repair station. 12