GM Blazer/Jimmy/Typhoon/Bravada 1983-1993 Repair Guide

Evaporator Core

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The evaporator is a device which cools and dehumidifies the air before it enters the vehicle. High pressure liquid refrigerant flows through the orifice tube into the low pressure area of the evaporator. The heat in the air passing through the evaporator core is lost to the cooler surface of the core, thereby cooling the air. As the process of heat loss from the air to the evaporator core surface is taking place, any moisture (humidity) in the air condenses on the outside surface of the evaporator core and is drained off as water. The core is located inside the blower motor/evaporator core case assembly, which is mounted to the passenger side of the cowl.


CAUTION
Please refer to General Information & Maintenance of this guide before discharging/recovering the A/C system or disconnecting air conditioning lines. Damage to the air conditioning system or personal injury could result. Consult your local laws concerning refrigerant discharge and recycling. In many areas it may be illegal for anyone but a certified technician to service the A/C system. Always use an approved recovery station when discharging the air conditioning.

REMOVAL & INSTALLATION



See Figure 1

  1. Either discharge and recover the refrigerant using a suitable recovery station, or have the system discharged by a professional shop.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. For 1992-93 vehicles, drain the engine cooling system to a level below the heater core, then disconnect the heater hoses from the core tubes.
  6.  
  7. For 1992-93 MFI-Turbo engines, remove the charge air cooler for access to the evaporator and blower assembly. For details, please refer to Engine & Engine Overhaul of this guide.
  8.  
  9. Remove the blower resistor with the wires attached.
  10.  
  11. Disengage the necessary electrical connectors from the blower motor and case components.
  12.  



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of a common A/C evaporator case assembly

  1. Remove the inlet line/evaporator tube from the A/C evaporator. Immediately plug all openings to prevent system contamination.
  2.  
  3. If necessary, remove the compressor hose assembly from the accumulator.
  4.  
  5. Remove the blower/evaporator case mounting nuts/screws, then remove the blower motor/evaporator case assembly from the vehicle.
  6.  
  7. Remove the accumulator inlet line from the evaporator and the accumulator. Immediately plug all openings to prevent system contamination.
  8.  
  9. Remove the blower motor case-to-evaporator case screws and separate the cases, then remove the evaporator core.
  10.  

To install:
  1. Install the evaporator core to the case, then join and secure the case assembly.
  2.  
  3. Remove the plugs, then install the accumulator inlet line to the evaporator and the accumulator.
  4.  
  5. Install the blower motor/evaporator case assembly to the vehicle and secure using the mounting nuts/screws. Tighten the fasteners until snug, but do not overtighten and crack the case.
  6.  
  7. If removed, install the compressor hose assembly to the accumulator.
  8.  
  9. Remove the plugs, then install the inlet line/evaporator tube to the A/C evaporator.
  10.  
  11. Engage the necessary electrical connectors to the blower motor and case components.
  12.  
  13. Install the blower resistor with the wires attached.
  14.  
  15. For 1992-93 MFI-Turbo engines, install the charge air cooler.
  16.  
  17. For 1992-93 vehicles, connect the heater hoses to the core tubes.
  18.  
  19. Connect the negative battery cable. For 1992-93 vehicles, properly refill the engine cooling system.
  20.  
  21. Either recharge the A/C refrigerant system or have the system recharged by a reputable shop.
  22.  

 
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