Hummer H1 (2006+). Manual - part 323

11-26 Heating/Ventilation/Air Conditioning (HVAC)

______________________

2.

Tighten the clamps.

3.

Refill the cooling system and check for leaks (Section 4).

WATER CONTROL VALVE

The water control valve determines when coolant will flow through the heater cores. The design of the valve allows the engine
coolant to flow around (bypass) the HVAC system when the temperature dial on the control head is moved to the cold position.
The valve is operated by vacuum directed by the control head. When vacuum is applied, the valve bypasses. When atmospheric
pressure is vented in, engine coolant flows through the heater cores (Figure  11-14).

WATER CONTROL VALVE REPLACEMENT

Removal

1.

Place a drain container under the vehicle directly below the control valve (Figure  11-14).

NOTE: Use extreme caution when working on a hot engine. Let the engine cool down before proceeding. 

2.

Relieve the pressure from the cooling system by loosening the coolant pressure cap.

3.

Remove the air intake hoses.

4.

Disconnect the vacuum hose from the control valve diaphragm.

5.

Clamp the control valve hoses with heater hose clamp pliers or equivalent tool.

6.

Remove the hoses from the valve.

7.

Remove the tie wrap and the valve from the mounting bracket.

Installation

CAUTION: Do not overtighten the tie wrap that secures the control valve to the mounting bracket. Overtightening can deform the
valve housing and cause binding. After tightening, push the plunger in and out of the vacuum diaphragm to ensure the valve is
moving freely.

1.

Gently secure the control valve to the mounting bracket with the tie wrap (Figure  11-14).

2.

Secure the hoses to the valve with the clamps.

3.

Release and remove the hose clamp pliers or equivalent tools from the valve hoses.

4.

Connect the valve vacuum hose (Figure  11-14).

5.

Check the coolant level and add coolant if necessary.

6.

Tighten the coolant pressure cap. 

7.

Check the valve for proper operation and leaks.

_____________________

 Heating/Ventilation/Air Conditioning (HVAC)  11-27

Figure 11-14:   Water Control Valve

DRAIN TUBE REPLACEMENT

Removal

1.

Remove the drain tube from the main HVAC unit inner cowl area by pulling straight out. If the drain tube grommet pulled out 
with the drain tube, it will need to be reinstalled. It may be necessary to loosen the drain tube from the main HVAC unit drain
outlet.

Installation

1.

Install the drain tube and the grommet, if removed, to the drain tube outlet on the main HVAC unit (Figure  11-15). Ensure the
drain tube is attached to the main HVAC unit drain outlet.

TO HEATER

FROM HEATER

TO ENGINE

FROM ENGINE

FROM VACUUM

WATER CONTROL

VALVE

MOUNTING

BRACKET

PLUNGER

CONTROL

TIE

STRAP

11-28 Heating/Ventilation/Air Conditioning (HVAC)

______________________

Figure 11-15:   Drain Tube Replacement

COMPRESSOR REPLACEMENT 

WARNING:  Air conditioning system components are subject to high-pressure refrigerant R-134a gas. Always dis-
charge pressure and contain R-134a using approved service equipment. Use extreme care when handling R-134a.
Direct contact with skin may cause frostbite. Do not smoke in areas where R-134a is stored or used. Failure to follow
these warnings may result in serious injury.

Removal

1.

Discharge the air conditioning system.

2.

Remove the belt from the A/C compressor.

3.

Remove the bolt and the discharge hose the from the A/C compressor (Figure  11-16).

4.

Remove the bolt and the suction hose from the A/C compressor (Figure  11-16).

5.

Discard the sealing washers and cap all of the openings.

6.

Disconnect the electrical connectors from the compressor.

7.

Remove the A/C compressor mounting bolt and remove the compressor.

Installation

1.

Install the A/C compressor and torque the mounting bolts to 37 lb-ft. (50 N·m).

2.

Connect the electrical connections.

3.

Remove the caps or tape from the hose and line ends.

4.

Install the A/C suction hose to the compressor using a new sealing washer. Torque the bolt to 12 lb-ft. (16 N·m).

5.

Install the A/C discharge hose to the compressor using a new sealing washer. Torque the bolt to 12 lb-ft. (16 N·m).

6.

Install the drive belt.

7.

Evacuate and recharge the A/C system.

8.

Leak test the fittings of the component using the J-39400-A leak detector.

GROMMET

DRAIN TUBE

_____________________

 Heating/Ventilation/Air Conditioning (HVAC)  11-29

Figure 11-16:   Receiver/Dryer 

RECEIVER/DRYER

The receiver/dryer provides storage for high pressure liquid refrigerant. Desiccant inside of the receiver/dryer assists in removing
moisture from the refrigerant. The receiver/dryer also acts as a filter, filtering out particles of debris and preventing bubbles of va-
por form entering the expansion valve (Figure  11-16).

AMBIENT TEMPERATURE SWITCH

The ambient temperature switch is mounted on the passenger side near the condenser. The switch, which monitors ambient air tem-
perature, is wired in series with the compressor activation circuit. The switch interrupts current flow to the compressor clutch when
outside temperature drops below 45°F (10°C).

CONDENSER

The condenser provides heat exchange for the A/C system. The condenser is located on the front of the radiator and cooler assem-
blies. Air from forward movement, and the engine cooling fan is forced through the fins of the condenser, removing heat from the
highly pressurized refrigerant. Refrigerant enters the condenser as a vapor and exits as a liquid.

CONDENSER

DISCHARGE HOSE

O-RING

P-CLAMP

RECEIVER

DRYER

EXPANSION VALVE

MANIFOLD BLOCK

OUTLETS

TO AUXILIARY

COMPRESSOR

LOW PRESSURE

CUT OFF SWITCH

SEALING WASHERS