Hummer H1 (2002+). Manual - part 186

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 Heating/Ventilation/Air Conditioning (HVAC)  11-23

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05745159

WATER CONTROL VALVE REPLACEMENT

Removal 

1.

Place a drain container under the vehicle directly below 
the control valve (Figure 11-19).

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

2.

Relieve pressure from cooling system by loosening
coolant pressure cap.

3.

Remove the air intake hoses.

4.

Disconnect the vacuum hose from the control valve
diaphragm.

5.

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

6.

Remove hoses from valve.

7.

Remove clamp and valve from mounting bracket.

Installation

CAUTION: Do not overtighten the clamp that secures the con-
trol valve to the mounting bracket. Overtightening the clamp
can deform the valve housing and cause binding. After tighten-
ing, push the plunger in and out of the vacuum diaphragm to
ensure the valve is moving freely.

1.

Gently secure control valve to mounting bracket with 
clamp (Figure 11-19).

2.

Secure hoses to valve with clamps.

3.

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

4.

Connect the valve vacuum hose (Figure 11-19).

5.

Check the coolant level and add coolant if necessary.

6.

Tighten coolant pressure cap. 

7.

Check the valve for proper operation and leaks. 

Figure 11-19:   Water Control Valve Installation

TO HEATER

FROM HEATER

TO ENGINE

FROM ENGINE

FROM VACUUM

SOLENOID

WATER CONTROL

VALVE

MOUNTING

BRACKET

CLAMP

PLUNGER

11-24

Heating/Ventilation/Air Conditioning (HVAC)

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MAIN A/C - HEAT UNIT COWL INSULATION 
REPLACEMENT

Removal

1.

Remove air intake weathercap (Section 3).

2.

Remove air cleaner assembly shield.

3.

Remove vent line from air cleaner assembly.

4.

Remove air cleaner assembly and air induction tube.

5.

Loosen and remove two clamps and move surge tank out
of the way.

6.

Remove drain tube.

7.

Remove trim screws, as necessary, from insulation on air
intake housing (Figure 11-20).

8.

Remove screws and washers, as necessary, from insulation
on upper cowl.

9.

Remove bolts, nuts, and fasteners, as necessary, from
insulation on front of cowl. 

10. Remove three nuts and washers from insulation on main

A/C - heat unit mounting studs.

11. Remove cowl insulation.

Figure 11-20:   Cowl Insulation Mounting

Installation

1.

Position cowl insulation so that flap side is inserted under 
surge tank bracket (Figure 11-20).

2.

Install three nuts and washers to secure insulation to main
A/C - heat unit mounting studs.

3.

Install bolts, nuts, and retainers as necessary to secure
insulation to front of cowl.

4.

Install screws and washers as necessary to secure
insulation to upper cowl.

5.

Install trim screws as necessary to secure insulation to air
intake housing.

6.

Install drain tube.

7.

Install two surge tank screw clamps to secure surge tank.

8.

Install air cleaner assembly and air induction tube (Section
3).

9.

Install air cleaner assembly vent line.

10. Install air cleaner assembly shield.

11. Install air intake weathercap.

DRAIN TUBE REPLACEMENT

Removal

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

Installation

Install drain tube and grommet, if removed, to drain tube outlet
on main A/C - heat unit (Figure 11-21). Ensure drain tube is at-
tached to main A/C - heat unit drain outlet. 

Figure 11-21:   Drain Tube Replacement

TRIM SCREWS

SEAL RETAINER

OVER INSULATION

FRONT

FASTENERS

AIR INTAKE 

HOUSING

UPPER
COWL

FLAP

COWL 

INSULATION

BLOWER MOTOR

RESISTOR

GROMMET

DRAIN TUBE

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 Heating/Ventilation/Air Conditioning (HVAC)  11-25

®

05745159

AIR CONDITIONING/HEATER DUCT 
REPLACEMENT

Passenger Floor Duct

Removal

1.

Remove right side crash pad (Section 10).

2.

Remove screw securing passenger side closeout panel to
upper closeout panel bracket (Figure 11-22).

3.

Lower panel down, and pull rearward to remove from
lower bracket (Figure 11-22).

4.

Remove screw securing duct hose to closeout panel
(Figure 11-22).

5.

Remove screw securing duct hose to the drivers floor duct
assembly (Figure 11-22).

6.

Remove duct hose

Installation

1.

Route new duct hose from drivers floor duct to closeout 
panel along right side of the main HVAC unit.

2.

Secure the duct hose at both ends with a trim screw.

3.

Put the bottom of the passenger side closeout panel into
the lower bracket., raise the rear to the upper mount
bracket and secure with a trim screw.

4.

Install crash pad.

Figure 11-22:   Passenger Floor Duct

Driver Floor Duct

The driver floor vent and floor duct are both integrated as part
of the closeout panel assembly. Failure of either component
constitutes closeout panel assembly replacement.

Removal

1.

Remove screws and closeout panel from instrument panel.

2.

Remove duct hose from driver floor duct on back side of
closeout panel.

Installation

1.

Attach duct hose to driver floor duct on back side of close-
out panel.

2.

Secure closeout panel to I. P. with screws.

Figure 11-23:   Driver floor Duct Appearance

7-S11-074

VENT

PASSENGER FLOOR

DRIVERS FLOOR DUCT

PASSENGER SIDE
CLOSEOUT PANEL

UPPER
BRACKET

CLOSEOUT

PANEL

DUCT
HOSE

CONNECTS

HERE

DRIVER

FLOOR

DUCT

DRIVER

FLOOR

VENT

CLOSEOUT

PANEL

(VIEWED

FROM BEHIND)

~

11-26

Heating/Ventilation/Air Conditioning (HVAC)

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DEFROST DUCT AND WINDSHIELD NOZZLES 
REPLACEMENT

Center Defrost Duct

Removal

1.

Remove right side crash pad (Section 10).

2.

Remove front console (Section 10).

3.

Remove engine cover (Section 10).

4.

Remove twelve screws, nuts, washers, and closeout panel
from A-beam (Figure 11-24).

5.

Remove eight screws, washers, and driver’s and pas-
senger’s lower windshield retainers from A-beam.

NOTE: Plusnuts must be drilled out in order to remove ducts.
New plusnuts are installed in the same holes. 

6.

Remove center defrost duct from A-beam.

Installation

1.

Install center windshield defrost duct into A-beam 
(Figure 11-24). Align both ends with adjacent duct and 
insuring a leak-free overlap joint. 

NOTE:  Apply Silaprene Sealant 05593929 in a continuous
bead around the new plusnuts making sure to cover both the
edge of the plusnut and the vehicle body. This will provide bet-
ter sealing. 

2.

Install new plusnuts into A-beam. 

3.

Install driver’s and passenger’s lower windshield retainers
on A-beam with eight screws and washers.

4.

Secure closeout panel to A-beam with twelve screws,
plusnuts, and washers.

5.

Install engine cover (Section 10).

6.

Install front console (Section 10).

7.

Check operation of windshield defrosters.

8.

Install right side crash pad (Section 10).

Figure 11-24:   Windshield Defrost Ducts and Nozzles

SIDE WINDOW

DEMISTER VENT HOSE

DRIVER WINDSHIELD

DEFROST NOZZLE

CENTER WINDSHIELD

DEFROST DUCT

PASSENGER WINDSHIELD

DEFROST NOZZLE

SIDE WINDOW

DEMISTER VENT HOSE

A-BEAM

DRIVER LOWER

WINDSHIELD RETAINER

CLOSEOUT PANEL

PLUSNUT