is  defective  and  should  be  replaced.  Check  voltage between  terminals  C2  of  armature  relay  (K4) and  ground  (El),  terminal  A2  of  armature  relay K5 and ground (El), and terminal B2 of armature relay  (K5)  and  ground  (El).  120  (±10)  vac should  be  indicated,  or  relay  is  defective  and should be replaced. Warning:   Be   careful   when  working with  high  voltage.  Failure  to  comply  can  result in  serious  injury  or  death. (3)  Removal. (a)  Refer  to  figure  3-4  and  remove  the lower  front  access  cover. (b)  Remove  cover  from  junction  box  (fig. 3-10). (c)  Refer  to  figure  3-13  and  remove  the relay. (4) Installation.   Installation  is  the  reverse of removal. c. Compressor  Start  Relay. (1) General.  The  compressor  start  relay  op- erates  in  conjunction  with  the  time  delay  relay (K3)  and  the  high-  and  low-pressure  cutout switches  (S6  and  S7)  to  insure  proper  starting sequence  of  the  refrigerant  compressor  when  ei- ther  S6  or  S7  require  non-operation. (2)   Testing. (a) Apply 208 volts, 60 Hertz, 3-phase, ac electrical  power  to  the  air  conditioner. (b) Place  rotary  switch  (S1)  in  COOL  po- sition. (c) Check  voltage  between  terminals  X1 and  X2  of  compressor  start  relay  (K1).  30  vdc (±3)  vdc  should  be  indicated.  If  30  vdc  is  indi- cated,  and  high-pressure  cutout  switch  (S6), low-pressure  cutout  switch  (S7)  and  time  delay relay (K3) are in operating condition, proceed to check  voltage  between  terminals  A2  and  B2,  B2 and  C2,  and  C2  and  A2.  If  208  vac  is  not  indi- cated, compressor relay is defective and must be replaced. If 30 vdc is not indicated between ter- minals X1 and X2 of relay (K1), check for phase ABC at phase sequence relay (K6) using a phase meter.  If  phasing  is  incorrect,  check  unit  incom- ing power. If phasing is correct, check terminal 2 of  relay  (K6)  for  110  vat.  If  110  vac  is  not  indi- cated, relay is defective and should be replaced. If  110  vac  is  indicated,  check  terminal  2  of  XF1 for  110  vat.  If  110  vac  is  not  indicated;  replace fuse.  Check  for  110  vac  at  terminal  3  of  XF1.  If 110 is not indicated, replace fuse. If 110 vac is in- dicated at terminals 2 and 3 of XF1, check for 30 vac at terminals X1 and X2 of transformer (T1). If  30  vac  is  not  indicated,  transformer  is  defec- tive and should be replaced. If 30 vac is indicated, check terminals 2 and 3 of rectifier (CRI) for 30 vdc.  If  30  vdc  is  not  indicated,  rectifier  is  defec- tive and should be replaced. If 30 vdc is indicated, check  terminal  2  of  XF2  for  30  vdc.  If  30  vdc  is not indicated, replace fuse. If 30 vdc is indicated, check  terminal  1  of  TB2  for  30  vdc  (rotary switch  must  be  in  COOL).  If  30  vdc  is  not  indi- cated, replace rotary switch (S1). If 30 vdc is in- dicated,  check  terminal  2  of  low-pressure  cutout switch (S7) for 30 vdc. If 30 vdc is not indicated, reset  switch  (S7)  and  recheck  for  30  vdc.  If  30 vdc is not indicated, replace low-pressure cutout switch  (S7).  If  30  vdc  is  indicated,  check  termi- nal  2  of  high-pressure  cutout  switch  (S6)  for  30 vdc. If 30 vdc is not indicated, reset switch (S6) and  recheck  for  30  vdc.  If  30  vdc  is  indicated, check  terminal  3  of  TB2  for  30  vdc.  If  30  vdc  is not indicated, remove plug (P4) and check resist- ance  between  pins  D  and  E  of  connector  (J4).  If no resistance, replace compressor. If resistance is indicated,  replace  connector  (J4).  If  30  vdc  is indicated  at  terminal  3  of  TB2,  check  terminals 5 and 7 of time delay relay (K3) for 30 vdc. If 30 vdc is not indicated at terminal 7 of K3, replace relay  (K3). (3)  Removal. (a)  Refer  to  figure  3-4  and  remove  the lower f rent access cover. (b) Remove  from  junction  box  (fig.  3-10). (c)  Refer  to  figure  3-13  and  remove  the relay. (4) Installation.   Installation  is  the  reverse of removal. d.  Heater  Relay. (1) General  The  heater  relay  (K2)  closes  to supply power to the electric heaters as called for by  the  KI-HEAT  or  LO-HEAT  setting  of  the  ro- tary selector switch (S2). (2)  Testing. (a)  Place   rotary   switch   (S1)   in   LO- HEAT position. (b) Apply 208 volts, 60 Hertz, 3-phase, ac electrical  power  to  the  air  conditioner. (c)  Check   voltage   between   terminals   Xl and X2 of heater relay (K2). 30 vdc should be in- dicated. If 30 vdc is indicated between terminals X 1 and X2, proceed to check voltage between ter- minals Al and B1, B1 and C1, and C1 and A1. If 30  vdc  is  not  indicated,  heater  relay  is  defective and must be replaced. If 30 (±3) vdc is not indi- cated,  check  for  30  vdc  to  ground  (El)  at  termi- nal  2  of  thermostat  (S2).  If  30  vdc  is  not  indi- cated at terminal 2 of thermostat (S2), check for phase ABC at phase sequence relay (K6), using a phase  meter.  If  phasing  is  incorrect,  check  unit incoming  power.  If  phasing  is  correct,  check  ter- minal 2 of relay (K6) for 110 vat. If 110 vac is in- 3-19