What the best way to change a heater-core on a.

HVAC MODULE ASSEMBLY REPLACEMENT

REMOVAL PROCEDURE

Drain the cooling system. Refer to Draining and Filling Cooling System in Cooling System.
Recover the refrigerant. Refer to Refrigerant Recovery and Recharging.
Disconnect the evaporator lines from the evaporator.
Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.
Disconnect the heater hoses at the heater core.
Lower the vehicle.
Remove the evaporator case drain tube.
Remove the inside and outside module attaching bolts and the accumulator mounting bracket bolt.
Remove the following components:

The instrument panel
For Chevrolet vehicles, refer to IP Carrier Replacement (Chevrolet).
For Pontiac vehicles, refer to IP Carrier Replacement (Pontiac).
The instrument panel tie bar
For Chevrolet vehicles, refer to Cross Vehicle Beam Replacement (Chevrolet).
For Pontiac vehicles, refer to Cross Vehicle Beam Replacement (Pontiac).

Remove the floor air outlet.
Disconnect the wiring harness from the module.
Disconnect the electrical connections at the following locations:

The blower motor
The blower resistor

Remove the module from the vehicle.

INSTALLATION PROCEDURE

Install the module in the vehicle.
Connect the electrical connections at the following locations:

The blower motor
The blower resistors

Connect the wiring harness to the module.
Install the floor air outlet.
Install the following components:

The instrument panel
For Chevrolet vehicles, refer to IP Carrier Replacement (Chevrolet).
For Pontiac vehicles, refer to IP Carrier Replacement (Pontiac).
The instrument panel tie bar
For Chevrolet vehicles, refer to Cross Vehicle Beam Replacement (Chevrolet).
For Pontiac vehicles, refer to Cross Vehicle Beam Replacement (Pontiac).

NOTE: Refer to Fastener Notice in Service Precautions.

Install the upper module attaching bolts.

Tighten
Tighten the bolts to 2 N.M (18 lb in).

Install the lower module attaching bolts.

Tighten
Tighten the bolts to 2 N.M (18 lb in).

Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle.
Install the evaporator case drain tube.
Connect the heater hoses to the heater core.
Lower the vehicle.
Connect the evaporator lines to the evaporator.

Tighten
Tighten the fittings to 24 N.M (18 lb ft).

Evacuate and charge the A/C system. Refer to Refrigerant Recovery and Recharging.
Fill the cooling system. Refer to Draining and Filling Cooling System in Cooling System.