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TM5-4120-377-14 a.   Inspection (1)  Inspect  for  evidence  of  leaks,  kinked,  or  otherwise  damaged  capillary  line,  and  loose  or  missing mounting   hardware. (2)  Check  thermal  bulb  to  see  that  is  is  securely  clamped  to  the  suction  line. (3)  If  a  leak  is  suspected  or  indicated,  test  per  paragraph  5-9. b.   Test (1)  Perform  a  refrigerant  pressure  check  on  unit  in  accordance  with  paragraph  5-12.  Leave  gages  or service   manifold   attached. (2)  Unwrap  insulation  tubing  from  compressor  suction  line  so  that  sensing  bulb  and  an  adjacent  section of  the  suction  line  is  exposed. (3)  Attach  an  accurate  thermometer  to  an  exposed  surface  to  suction  line  adjacent  to  the  sensing  bulb; use  a  small  gob  of  thermal  mastic,  to  improve  conductivity. (4) Check that service valve and gage connection to low (suction) side are open. Note pressure indicated on  gage  and  temperature  indicated  on  thermometer. (5)  Set  the  TEMPerature  control  thermostat  knob  to  full  INCREASE  (clockwise).  Start  the  air  conditioner in  COOL  mode.  Note  that  suction  pressure  drops  to  58  ±  2  psig  (4.0  ±  0.2  kg/cm2).  Allow  compressor  to  run for  at  least  20  minutes.  If  pressure  is  not  within  above  limits,  test  operation  of  pressure  regulating  valve  (para 5-24)  before  proceeding  with  quench  valve  test. NOTE Except   in   a   very   hot   climate,   with   room   air   temperature   above   90°F   (32.2°C),   the refrigeration  system  will  be  in  a  bypass  cycle  with  a  maximum  volume  of  hot  discharge vapor  being  recirculated  back  to  suction  side  of  compressor  through  pressure  regulator valve  and  quench  valve. (6) Observe that temperature indicated remains stable for a minimum of two minutes, then find saturation temperature  for  pressure  indicated  on  gage,  using  table  5-1.  For  example:  The  saturation  temperature  for  a refrigerant  pressure  pf  69  psig  (4.85  kg/cm2) is 40°F (4.4°C). (7)  Compare  the  saturation  temperature  with  indicated  temperature.  The  indicated  temperature  should be   25   ±   5°F   (13.9   ±   2.2°C)   higher   than   the   saturation   temperature.   For   example:   With   a   40°   saturation temperature,   the   thermometer   should   read   65   ±   5°F.   If   indicated   temperature   is   not   within   above   limits, quench  valve  is  not  functioning  properly  and  should  be  adjusted: If  valve  does  not  need  adjustment,  skip  (8)  below. (8) If the superheat setting is not within the limits shown above, adjust the liquid quench expansion valve as  follows: (a)  Remove  the  hexagonal  seal  cap  from  the  side  of  the  power  assembly. (b) Turn the adjusting stem two complete turns to change the superheat setting by 1°F (0.55°C). Turn the stem clockwise to increase superheat span; counterclockwise to decrease it. Do not change more than two full  turns  at  one  time,  then  wait  at  least  2  minutes  for  temperature  to  stabilize  and  recheck  pressure  and temperature  before  further  adjustment.  If  valve  cannot  be  properly  adjusted,  replace  the  valve. 5-33

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