Hummer H1 (2006+). Manual - part 328

11-46 Heating/Ventilation/Air Conditioning (HVAC)

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Figure 11-45:   Evaporator Extension Tubes Removal

Installation

1.

Obtain a new evaporator. Ensure that any foam tape found on the previously removed unit is duplicated on the replacement. 

2.

Install the extension tubes onto the new evaporator using new o-rings lubricated with refrigerant oil.

3.

Install the evaporator into the original case half.

4.

Position the thermostat capillary tube in the same location it was removed from on the original evaporator. It will be necessary
to hot glue the tube near the exit hole (Figure  11-44). 

5.

Install the second half of the HVAC unit, ensuring that the edges of the case halves engage the S clips around the seam.

6.

Install the screws securing the two halves together. 

7.

Using a neutral cure silicone sealer, seal the entire perimeter of the seam.

8.

Install the passthrough plate onto the main unit and the evaporator. Install the bolt securing the evaporator extension tubes to
the passthrough plate. Use a new sealing washer between the passthrough plate and the evaporator extension tubes. 

NOTE: It may be necessary to trim the center from the gasket as received. The normal span of the gasket will not fit the evaporator
extension tube span.

9.

Install the expansion valve with a new sealing washer and torque to 100 in lbs.

10. Install the Vacuum motor bracket onto the main unit

11. Install the defrost door motor onto the mounting plate.

12. Connect all the vacuum motors to their perspective door arms using the washers and a new push clips.

13. Install a new door travel limiting rivet into the case, placing the door on the side of the rivet it was originally resting on.

14. Install the air intake assembly onto the main case.

15. Install the lower support bracket. 

16. Install the heater core and the retaining brackets, using a new sealing washers on the heater core tubes. Torque the heater

manifold to 32 in-lbs.

17. Install the vacuum harness onto the vacuum motors.

18. Install the unit into the vehicle (Refer to section11).

19. Fill the cooling system.

20. Evacuate the A/C system for a minimum of 45 minutes, with a 10 minute hold time for a leak check. Charge with 2 lbs 4 oz. of

R-134A refrigerant, adding the same amount of oil that was drained from the original evaporator.

EXTENSION TUBES

EVAPORATOR

7-S11-045

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 Heating/Ventilation/Air Conditioning (HVAC)  11-47

Thermostatic Cycling Switch Replacement 

Removal

1.

Remove the evaporator (Refer to section 11).

2.

Carefully remove the capillary tube from the evaporator, noting the positioning in the evaporator fins (Figure  11-44).

3.

Remove the two screws and remove the thermostatic cycling switch from the HVAC unit.

Installation

1.

Secure the thermostatic cycling switch to the HVAC unit with the two screws.

2.

Install the evaporator into the original case half.

3.

Position the thermostat capillary tube in the same location it was removed from on the original evaporator. It will be necessary
to hot glue the tube near the exit hole (Figure  11-44).

4.

Install the evaporator and the main HVAC unit into vehicle (Refer to section 11).

Air Intake Assembly Replacement

Removal

1.

Remove the main HVAC unit (Refer to section 11).

2.

Remove the air intake housing from the main unit by removing the attaching screws at the blower housing (Figure  11-39) and
the bracket at the front of the unit (Figure  11-38).

Installation

1.

Install the air intake housing on the main HVAC unit and secure with the screws.

2.

Install the main HVAC unit into the vehicle (Refer to section 11).

AUXILIARY AIR CONDITIONING/HEATING UNIT 

The auxiliary HVAC unit is utilized to enhance the heating and cooling of the Hummer. The unit is located under the center con-
sole. A secondary evaporator in parallel with the front evaporator and a heater core in parallel with the front heater core and a sec-
ond blower motor are included. The auxiliary unit requires that the front heater or A/C system be operating for heating or cooling.
The auxiliary blower motor operates with a switch on the engine console, with two available speeds, high and low. There is a re-
frigerant cut-off solenoid for the auxiliary unit to stop refrigerant flow when the temperature control knob is in the heat position
and the A/C compressor is running in the defrost mode.

AUXILIARY AIR CONDITIONING/HEATING UNIT REPLACEMENT

Removal

1.

Discharge the air conditioning system.

2.

Remove the center console (Refer to section 10).

3.

Install hose pinch pliers on heater hoses to minimize coolant loss.

4.

Remove the heater hoses from the auxiliary unit heater core ports (Figure  11-47).

5.

Remove the A/C hoses from the auxiliary unit. 

6.

Remove the drain tubes from the auxiliary unit (Figure  11-47).

11-48 Heating/Ventilation/Air Conditioning (HVAC)

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Figure 11-46:   Auxiliary A/C Components

Figure 11-47:   Auxiliary Heater Hose Routing

7.

Remove the screws securing the side brackets to the tunnel mounting bracket.

8.

Remove the auxiliary unit from the vehicle.

Installation

1.

Install the auxiliary unit in the vehicle and secure the side brackets to the tunnel mounting bracket with the screws (Figure
 11-46).

2.

Install the drain tubes on the auxiliary unit (Figure  11-47).

3.

Install the A/C hoses on the auxiliary unit.

4.

Wrap the low pressure fitting with prestite tape.

5.

Secure the heater hoses to the heater core ports on the auxiliary unit with the constant tension clamps. Remove the hose pinch
pliers.

6.

Evacuate, charge, and leak test the air conditioning system.

7.

Check the engine coolant level and add coolant as necessary.

8.

Start the engine and operate the auxiliary and the front air conditioning system to check for proper operation.

9.

Check the coolant connections for leakage, repair if necessary.

10. Stop the engine, recheck the coolant level and add coolant if necessary.

11. Install the center console (Refer to section 10). 

MOUNTING

SMALL

LARGE

O-RING

AUXILIARY UNIT

BRACKET

SELF-TAPPING

SCREW

 A/C HOSE

 A/C HOSE

DRAIN

TUBES

HEATER

CORE

PORTS

CLAMP

HEATER

HOSES

DRAIN TUBES

AND TEE

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 Heating/Ventilation/Air Conditioning (HVAC)  11-49

AUXILIARY BLOWER SWITCH REPLACEMENT

Removal

1.

Remove the four screws securing the center dash bezel and the bezel.

2.

Remove the connector from the back of the blower switch (Figure  11-48)

3.

Depress the tabs on the blower switch and push the switch through the faceplate.

Installation

1.

Push the blower switch into the opening in the bezel.

2.

Secure the connector to the blower switch and check the operation (Figure  11-48).

3.

Install the center dash bezel and secure with the four screws.

Figure 11-48:   Blower Switch Replacement

AUXILIARY HEATER HOSE REPLACEMENT

NOTE: Heater hose replacement is the same for both heater hoses.

NOTE: Production heater hose will have full underbody length of foil back insulation sleeve. Make sure the replacement hose also
has this protection. 

Removal

1.

Drain the cooling system (Refer to section 4).

2.

Remove the air cleaner induction tube (Refer to section 3).

3.

Select the heater hose to replace, loosen the hose clamps and remove the heater hose from the hose splice.

4.

Remove the two P-clamps from the underbody securing the auxiliary hoses.

5.

Remove the center console.

6.

Remove the constant tension clamps securing the heater hose to the heater and to the core port on the auxiliary unit (Figure
 11-47).

7.

Pull the heater hose through the tunnel grommet.

8.

Remove the heater hose.

CONNECTOR

AUX

BLOWER SWITCH

CENTER

DASH

ASSEMBLY

CENTER

DASH

ASSEMBLY

BEZEL