GM Full-Size Trucks 1970-1979 Repair Guide

Auxiliary Air Conditioning System

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REMOVAL & INSTALLATION



Suburban

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: View of the auxiliary A/C system components found on the Suburban

OVERHEAD DUCT
  1. Disconnect the negative battery cable.
  2.  
  3. Disconnect the condensation drain tube from the rear duct.
  4.  
  5. Remove the screws securing the duct to the roof panel. Remove the rear header bracket.
  6.  
  7. Remove the duct assembly.
  8.  
  9. Installation is the reverse of the removal procedure.
  10.  

BLOWER MOTOR ASSEMBLY
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the rear duct assembly.
  4.  
  5. Disconnect the blower motor lead wire and the motor ground strap.
  6.  
  7. Remove the lower to upper blower/evaporator case screws. Lower the lower case and motor assembly. Before removing the case assembly screws, support the case to prevent damage to the motor or case.
  8.  
  9. Remove the motor retaining strap and remove the motor and wheels. The wheels can be removed from the motor shaft.
  10.  
  11. Installation is the reverse of the removal procedure. Be sure the blower wheels rotate freely and no binding exists.
  12.  

EXPANSION VALVE
  1. If equipped, have the A/C system properly discharged by a reputable repair shop.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the rear duct assembly.
  6.  
  7. Disconnect the blower motor lead and ground wires.
  8.  
  9. Remove the loser to upper blower/evaporator case screws. Lower the case and motor assembly. Before removing the case screws, support the case assembly to avoid damage to the motor/evaporator case assembly.
  10.  
  11. Remove the expansion valve sensing bulb clamps.
  12.  
  13. Disconnect the valve inlet and outlet lines. Remove the expansion valve assembly. Cap the openings immediately.
  14.  
  15. Installation is the reverse of the removal procedure.
  16.  
  17. If equipped, take the truck to a reputable repair shop to have the A/C system evacuated, charged and leak tested, using the correct equipment.
  18.  

EVAPORATOR CORE
  1. If equipped, have the A/C system properly discharged by a reputable repair shop.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Remove the rear duct. Disconnect the power lead and the ground lead to the blower motor.
  6.  
  7. Disconnect the refrigerant lines at the rear of the blower/evaporator assembly. Cap the openings immediately.
  8.  
  9. Support the blower/evaporator assembly and remove the retaining screws between the case and the roof rail. Lower the blower/evaporator assembly and place it on a work area away from the vehicle.
  10.  
  11. Remove the lower to upper case screws and remove the lower case assembly. Remove the support to upper case screws and remove the upper case from the evaporator core.
  12.  
  13. Remove the expansion valve inlet and outlet lines. Cap the openings immediately. Remove the expansion valve capillary tube from the evaporator outlet line and remove the valve.
  14.  
  15. Remove the plastic pins holding the screen to the core. Remove the screen.
  16.  
  17. The installation of the evaporator core is the reverse of the removal procedure. New O-rings must be used and lubricated with fresh refrigerant oil. Install the sensing bulb to the evaporator outlet tube, making sure the tube is in proper contact with the line.
  18.  
  19. Add three fluid ounces of refrigerant oil to the evaporator.
  20.  
  21. If equipped, take the truck to a reputable repair shop to have the A/C system evacuated, charged and leak tested, using the correct equipment.
  22.  

 
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