TRUCK SERVICE MANUAL TM 5-4210-230-14&P-1 BODIES AND CABS 9. Remove control cable mounting bracket. 10. Disconnect -adjustable link from blend air door. 11. Rotate    control    valve    assembly    as    necessary    to withdraw   lower   neck   of   valve   through   grommet   in bottom  of  heater/evaporator  unit  housing.    Remove valve (Fig. 54). Fig. 54 Removing Hot Water Flow Control Valve from Unit Housing 12. Disconnect  hose  clamp  and  remove  valve-to-heater core hose from valve. 13. Inspect    all    hoses    and    control    valve    inlet    neck grommet    in    bottom    of    unit    housing.    Replace    if damaged or deteriorated. Installation: 1. Position  control  valve-to-heater  cover  hose  on  valve and tighten hose clamp. 2. Insert    lower    neck    of    flow    control    valve    through grommet in bottom of heater/evaporator unit housing and rotate valve assembly into position. 3. Connect adjustable link to blend air door. 4. Position   flange   of   control   cable   mounting   bracket under mounting flange of control valve. 5. Install and tighten valve mounting screws. 6. Connect inlet hose to lower neck of flow control valve and tighten hose clamp. 7. Install heater core as follows: a. Make  sure  gaskets  are  in  position  on  ends  of heater core. b. Open blend air door. c. Position heater core into housing.  Align slot in heater core frame with rivet at front of housing and push core into position. d. Install heater core mounting screws. e. Connect hoses to heater core and tighten hose clamps. 8. Connect  control  cable  to  blend  air  door  and  install cable mounting screw. 9. Adjust control cable as outlined under "Control Cable Adjustment". 10. Refill engine cooling system. 11. Set  heater  (HTR)  control  at  "HOT".    Operate  engine and check for coolant leaks and for proper operation of flow control valve. 12. Install covers on heater/evaporator unit and instrument panel. 13. Lower hood and fender assembly. LOW PRESSURE SWITCH The   low   pressure   switch   can   be   replaced   without discharging  the  refrigerant  from  the  air  conditioning  system. A  spring-loaded  valve  in  the  switch  mounting  adapter  on  the evaporator outlet pipe prevents loss of refrigerant when switch is removed. Removal: 1. Make sure key switch is "OFF". 2. Remove cover from right side of instrument panel. 3. Remove cover from heater/evaporator unit. 4. Disconnect   low   pressure   switch   wires   from   wiring harness. 5. Using   two   wrenches,   remove   low   pressure   switch from adapter on evaporator outlet pipe (Fig. 55). CTS-2731  Page 37 PRINTED IN UNITED STATES OF AMERICA