SERVICE MANUAL 12. Insert  eight  cap  screws  to  attach  bottom  cap  to body   tube   and   deflector   assembly.       Tighten alternately and evenly to 20.3 Nm (15 ft.  lbs.).  If unit previously had old style deflector attached to bottom   cap,   use   the   eight   longer   cap   screws contained in the deflector replacement kit. 13. Reconnect  the  air  line  to  the  inlet  port  (this  line leads from the compressor service port). 14. Reconnect    the    governor    control    line    to    the unloader  port  in  unloader  nut  (Item  27  of  Fig. 23). 15. Reconnect the wire to the heater. 16. Test  the  unit  following  the  instructions  listed  in SERVICE CHECKS. Servicing Check Valve Assembly There  are  several  indications  which  may  mean that the check valve needs servicing: Air     is     exhausted     from     exhaust     port     when compressor is in stand-by mode. System  air  pressure  bleeds  off  rapidly  when  air using equipment is not being operated. Compressor goes into stand by mode but cycles rapidly. Compressor    attempts    to    build    pressure    but system pressure will not build up. Safety valve opens. These    situations    can    be    caused    by    several conditions.  Check ’the TROUBLE SHOOTING GUIDE to make    sure    that    the    probable    cause    is    a    defective assembly.    The  following  is  the  procedure  for  servicing and replacing the check valve assembly. Refer to Fig. 26 for numbers in parenthesis. 1. Refer to the General Instructions. 2. Disconnect air line at outlet port at top of unit. 3. Remove top nut (4).  This nut is spring loaded. 4. Remove   copper   gaskets   (3),   spring   (1),   and check valve spindle (2). 5. Clean  and  dry  entire  check  valve  area  and  top nut (4). 6. Position  new  check  valve  spindle  (2)  in  top  cap with tapered end down. Fig. 26  Check Valve Assembly 1 Spring 3 Gaskets 2 Spindle 4 Nut 7. Install spring (1) in check valve spindle. 8. Position  new  copper  gaskets  (3)  in  nut  (4)  and rub a small quantity of grease on the gaskets to help them keep their position in the top nut. 9. Thread  nut  on  to  top  cap  and  torque  to  81  Nm (60 ft.  lbs.).  Top nut (4) is not included in check valve replacement kit. 10. Reconnect  the  air  line  to  the  outlet  port.    The safety   valve   (Item   41   of   Fig.   23)   cannot   be serviced  and  it  is  recommended  that  it  not  be removed  from  the  top  cap.    If  the  safety  valve was   removed,   apply   non-hardening   sealant   to threads of top cap. 11. Test  the  unit  following  the  instructions  listed  in SERVICE CHECKS. Servicing Filter Assembly Although    the    filter    assembly    of    the    unit    is designed  to  require  little  or  no  servicing,  it  is  a  good practice  to  service  the  filter  assembly  when  performing service  on  the  other  filters  located  on  the  vehicle.    This servicing can be accomplished in one of two ways, either replacing  the  entire  filter  assembly,  or  by  servicing  the filter assembly.  In most cases, simply servicing will only be necessary.  The following  are  the  steps  for  servicing the filter assembly.   If  the  entire  filter  assembly  is  being replaced, those steps preceded by an asterisk (*) can be eliminated. Refer to Fig. 27 for numbers in parenthesis. 1. Refer to the General Instructions. 2. Remove air line at outlet port. CTS-4079 - CHAPTER XIV - Page 17