| Subject: | Revised Evaporator Core Replacement Procedure | 
| Models: | 1997-2001 Chevrolet and GMC M/L-Van | 
 
This bulletin is being issued to revise the Evaporator Core Replacement
procedure in the Heating, Ventilation and Air Conditioning sub-section of
the Service Manual. Please replace the current information in the Service
Manual with the following information.
The following information has been updated within SI2000. If you are
using a paper version of this Service Manual, please make a reference to this
bulletin on the affected page.
Removal Procedure
- Remove the air cleaner. Refer to Air Cleaner Assembly Replacement.
 
- Recover the refrigerant from the system. Refer to Refrigerant
Recovery and Recharging.
 
- Remove the coolant recovery reservoir. Refer to Coolant Recovery
Reservoir Replacement.
 
- Disconnect the electrical    connectors.
 
- Remove the compressor hose assembly from the accumulator. Refer
to Compressor/Condenser Hose Replacement - Auxiliary.
 
- Remove the bypass valve bracket from the outer case.
 
- Remove the evaporator tube from the accumulator.
 
- Remove the relay bracket.
 
- Remove the evaporator tube from the evaporator. Refer to the appropriate
procedure:
 
| •  | Evaporator Tube Replacement | 
 
| •  | Evaporator Tube Replacement - Auxiliary Front | 
 
- Remove the screws from  the  outer  evaporator
case.
 
- Remove the outer case from the module.
 
- Remove the screws in order to split the evaporator module in half.
 
- Remove the inner case from the module.
 
- Remove the evaporator core.
 
Installation Procedure
- Install the  evaporator   core.
 
Notice: Refer to Fastener Notice in Cautions and Notices.
- Install the inner case to the evaporator module.
 
Tighten
Tighten the screws to the evaporator case to 6 N·m   (53 lb in).
- Install the outer case to the evaporator module.
 
Tighten
Tighten the screws to the evaporator case to 6 N·m   (53 lb in).
- Install the evaporator tube to the evaporator.
 
| •  | Evaporator Tube Replacement | 
 
| •  | Evaporator Tube Replacement - Auxiliary Front | 
 
- Install the bypass valve bracket to the outer case.
 
- Install the evaporator to the accumulator.
 
- Install the compressor hose assembly to the accumulator. Refer
     to Compressor/Condenser Hose Replacement - Auxiliary.
 
- Install the relay bracket.
 
- Connect the electrical connectors.
 
- Install the coolant recovery reservoir. Refer to Coolant Recovery
Reservoir Replacement.
 
- Refill the engine coolant. Refer to Draining and Filling Cooling
System.
 
- Evacuate and recharge the system. Refer to Refrigerant Recovery
and Recharging.
 
- Install the air cleaner. Refer to Air Cleaner Assembly Replacement.