Hummer H1 (2002+). Manual - part 185

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 Heating/Ventilation/Air Conditioning (HVAC)  11-19

®

05745159

Discharge Hose Replacement

Removal

1.

Disconnect discharge hose from condenser. Remove and 
discard O-ring (Figure 11-12).

2.

Remove driver side engine splash shield (Section 10).

Figure 11-12:   Discharge Hose Location

3.

Remove tie strap securing discharge hose to oil cooler
lines. Discard tie strap.

4.

Remove discharge hose from compressor block and
discard O-ring  (Figure 11-10). 

Installation 

CAUTION: To avoid potential thread or fitting damage, hand
start connections before using wrenches. 

1.

Position O-ring on discharge hose (Figure 11-10).

2.

Secure discharge hose to compressor block. Torque fitting
to 15-20 lb-ft (20-27 N•m). 

3.

Lubricate O-ring, position on discharge hose, and connect
hose to condenser. Using two wrenches for equalized
support, tighten to 15-20 lb-ft (20-27 N•m).

4.

Secure discharge hose to oil cooler lines with tie strap.

5.

Install driver side engine splash shield.

6.

Evacuate and charge air conditioning system.

7.

Check for system leaks.

8.

Check A/C operation.

Condenser-to-Receiver/Dryer Hose 

WARNING:  Air conditioning system components are
subject to high pressure R-134a gas. Always discharge
pressure and contain refrigerant 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 

CAUTION: To avoid potential thread or fitting damage, hand
start connections before using wrenches. 

1.

Discharge air conditioning system.

2.

Disconnect hose from condenser and remove O-ring.
Discard O-ring (Figure 11-13).

3.

Remove hose and O-ring from receiver/dryer. Discard O-
ring.

Figure 11-13:   Receiver/Dryer Location

Installation

1.

Lubricate O-ring with PAG oil, position on hose, and 
secure hose to condenser. Using two wrenches for equal-
ized support, tighten to 11-13 lb-ft (15-18 N•m).

2.

Lubricate O-ring with PAG oil, position on hose, and
secure hose to receiver/dryer. Using two wrenches for
equalized support, tighten to 11-13 lb-ft (15-18 N•m).

3.

Evacuate and charge air conditioning system.

4.

Check system for leaks.

5.

Check air conditioning system operation.

CONDENSER

DISCHARGE HOSE

OIL 

 LINES

TIE STRAP

COOLER

O-RING

HOSE

CONDENSER

RECEIVER

 DRYER

TO EVAPORATOR

11-20

Heating/Ventilation/Air Conditioning (HVAC)

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®

Receiver/Dryer-To-Evaporator Core Hose 

WARNING:  Air conditioning system components are
subject to high pressure R-134a gas. Always discharge
pressure and contain refrigerant 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 air conditioning system.

2.

Disconnect hose from receiver/dryer and remove O-ring.
Discard O-ring (Figure 11-13).

3.

Disconnect auxiliary hose connection (if equipped).

4.

Remove hose and O-ring from expansion valve manifold
block. Discard O-ring (Figure 11-11)

Installation 

1.

Lubricate two O-rings with PAG oil and position on hose 
(Figure 11-11).

2.

Secure hose to expansion valve manifold block. Using two
wrenches for equalized support, tighten to 11-13 lb-ft (15-
18 N•m).

3.

Torque auxiliary unit line to 11-13 lb-ft (15-18 N•m).

4.

Secure hose to receiver/dryer. Using two wrenches for
equalized support, tighten to 11-13 lb-ft (15-18 N•m)
(Figure 11-13).

5.

Leak test system.

CONDENSER REPLACEMENT

Removal 

WARNING:  Air conditioning system components are
subject to high pressure R-134a gas. Always discharge
pressure and contain refrigerant 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.

1.

Discharge air conditioning system.

NOTE: Cover all open lines to prevent contamination.

2.

Disconnect two pressure hoses from condenser and
remove O-rings. Discard O-rings.

Figure 11-14:   Condenser Replacement 

3.

Remove screws, washers, spacers, and condenser from oil
cooler  (Figure 11-14).

Installation 

1.

Secure condenser to oil cooler with spacers, washers, and 
screws (Figure 11-14).

2.

Lubricate two O-rings with PAG oil and install on
pressure lines.

3.

Connect two pressure hoses to condenser.

4.

Evacuate and charge air conditioning system.

CONDENSER

OIL

COOLER

_____________________

 Heating/Ventilation/Air Conditioning (HVAC)  11-21

®

05745159

RECEIVER/DRYER REPLACEMENT

Removal 

WARNING:  Air conditioning system components are
subject to high-pressure R-134a gas. Always discharge
pressure and contain refrigerant 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.

NOTE: The receiver/dryer will quickly absorb water from the
atmosphere when not sealed. Do not leave system open during
service. Receiver/Dryer should be replaced any time major
components are replaced. If in doubt, replace unit. 

1.

Discharge air conditioning system.

2.

Disconnect electrical connector from high/low pressure
switch (Figure 11-15).

NOTE: Cover all open lines to prevent contamination.

3.

Disconnect two hoses from receiver/dryer and remove O-
rings. Discard O-rings.

4.

Remove two clamps and receiver/dryer from bracket.

Figure 11-15:   Receiver/Dryer

Installation 

1.

Secure receiver/dryer to bracket with two clamps. Position 
hose attachment ports to front and rear of vehicle 
(Figure 11-15).

2.

Lubricate two O-rings with PAG oil and position on hose
fittings.

3.

Connect two hoses to receiver/dryer.

4.

Connect electrical connector to high/low pressure switch.

5.

Test the system for leaks.

RECEIVER/DRYER PRESSURE SWITCH 
REPLACEMENT

Removal 

1.

Disconnect pressure switch jumper connector from 
receiver/dryer pressure switch (Figure 11-16).

NOTE: Unscrew the pressure switch as quickly as possible to
avoid excessive loss of refrigerant.

2.

Using a wrench, remove the pressure switch from the
receiver/dryer. 

Figure 11-16:   Receiver/Dryer Pressure Switch 

Mounting

Installation

1.

Thread the new pressure switch on the receiver/dryer fit-
ting by hand and use a wrench to finish securing the pres-
sure switch. (Figure 11-16). 

NOTE:  Install the pressure switch as quickly as possible to
avoid excessive loss of refrigerant.

2.

Connect the pressure switch jumper electrical connector to
the pressure switch.

3.

Check the pressure switch fitting for leaks using suitable
leak-testing equipment.

HOSE

HOSE

HIGH/LOW 

BRACKET

RECEIVER 

CLAMPS

PRESSURE SWITCH

DRYER

CONNECTOR

O-RINGS

RECEIVER/DRYER 

RECEIVER/

RECEIVER/DRYER 

ELECTRICAL CONNECTOR

PRESSURE SWITCH

 DRYER

11-22

Heating/Ventilation/Air Conditioning (HVAC)

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®

HEATER HOSE REPLACEMENT

Engine coolant is routed through 5/8 inch diameter heater hose
from the engine water crossover to the bottom fitting of the
heater shutoff valve. When the valve is open, coolant flows
through another length of hose from the valve’s rearward lower
fitting to the heater core inlet port. The heater outlet hose is
routed to the valve’s rearward upper fitting on vehicles without
an auxiliary A/C - heat unit. On vehicles equipped with an aux-
iliary unit, the heater outlet hose is routed to the auxiliary
heater core inlet—then from the auxiliary heater core outlet to
the rearward upper fitting on the heater shutoff valve. The
coolant return hose is routed from the forward upper heater
shutoff valve fitting to the water pump nipple (Figure 11-17).

Removal

1.

Drain cooling system (Section 4).

2.

Loosen worm gear clamps on either end of hose to be
removed.

NOTE: Damage to the heater core can result if too much force
is applied to the ports. If the hose is not easily removed by
moderate twisting and pulling, cut the hose just beyond the
port. Then cut the hose remaining on the port lengthwise and
remove it.

3.

Remove hose ends from fittings by twisting and pulling.

Figure 11-17:   Heater Hose Routing Without 

Auxiliary Unit

Installation

1.

With clamps loosely in place, connect hose ends to respec-
tive fittings.

2.

Tighten clamps.

3.

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

WATER CONTROL VALVE

The water control valve determines when coolant will flow
through the heater core(s). 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 core(s) (Figure 11-18).

Figure 11-18:   Water Control Valve

5/8" DIAMETER

HEATER HOSE

5/8" DIAMETER

HEATER HOSE

HEATER SHUTOFF VALVE

WATER 
CONTROL

VALVE

MOUNTING
BRACKET

6-S11-008