Hummer H1 (2002+). Manual - part 181

 

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 Heating/Ventilation/Air Conditioning (HVAC)  11-3

 

 

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05745159

 

A/C System Leak Testing

 

There are two methods of detecting refrigerant leaks. One
method is with the use of an electronic leak detector and the
other uses a flourescent tracer dye in the refridgerant which is
viewed at the leak site with an ultra violet (black) light.

 

Dye leak testing

 

R134a florescent dye will remain in the lubricant for the life of
the vehicle as long as the vehicle’s AC system has not been
flushed. To perform a dye leak test, do the following:

1.

Recover the existing R134a refridgerant and record the 
refridgerant weight.

2.

Add R134a florescent dye J–41447 using the dye injector
J–41459.

3.

Recharge the AC system following the procedures
outlined in chapter 11.

4.

Check for leaks using the high intensity black light
J-42220. If no leaks can be found, advise the customer of
the dye in the system and that it may need to be checked at
a later date. 

 

Figure 11-1:   Dye Injector Use

 

Electronic leak testing

 

Recommended electronic leak detector is the D-Tek, pocket
portable model (Figure 11-2). It is self powered by NiCad bat-
teries, extremely compact, and will locate leaks as small as 1/4
ounce. The Kent-Moore Tool number is J–41995.

 

Figure 11-2:    D-Tek Leak Detector

 

The D-Tek probe is flexible and can be used to make a 360

 

o

 

check of each hose connector and fitting. The correct method
of leak testing fittings is shown in  Figure 11-2.1.

 

Figure 11-2.1   Leak Testing Technique at 

Connections

 

A/C system potential leak points are outlined in  Figure 1-3. Be
sure to check each fitting and connector carefully with the D-
Tek tool.

00-S11-008

DYE

INJECTOR

 

4-1-00

 

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Heating/Ventilation/Air Conditioning (HVAC)

 

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CONNECTOR IDENTIFICATION

 

COMPRESSOR-OUT

CONDENSER - IN

CONDENSER - OUT

DRYER - IN

DRYER - OUT

H/P AUX TEE - IN

H/P AUX TEE - OUT

AUX EVAP - IN

AUX EVAP - OUT

MAIN EVAP - IN

MAIN EVAP - OUT

L/P AUX TEE - IN

L/P AUX TEE - OUT

COMPRESSOR - IN

COMPRESSOR - FRONT SEAL

SCHRADER VALVES

 

NOTE: 

 

Move detector wand at a slow, consistent rate above and below and around fittings/connnections. Carefully inspect all

hose connections to metal ferrules on crimp shells. Also test the small inspection holes on the shells.

 

Figure 1-3:   A/C System Leak Check Points

 

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 Heating/Ventilation/Air Conditioning (HVAC)  11-5

  

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05745159

 

A/C SYSTEM REFRIGERANT AND CAPACITY

 

The required refrigerant for Hummer A/C systems is R-134a.
This is a colorless, odorless non-flammable, liquefied gas. 

A special refrigerant oil is required for use with R-134a which
is polyalkaline glycol (PAG). This is the only oil that can be
used with R-134a refrigerant. More specifically, General Mo-
tors®  PAG oil must be used with the A/C compressor on the
HUMMER.

 

CAUTION: 

 

R12 and R-134a refrigerants are 

 

not

 

 compatible.

They must never be intermixed. Unsatisfactory cooling, rapid
sludge buildup, and compressor failure will result. System re-
frigerant capacity is:

 

3 lbs 2 oz 

 

R-134a Refrigerant Precautions

 

To avoid product damage and personal injury, the following
precautions should be followed when working with R-134a re-
frigerant.

• Wear safety goggles when servicing the A/C system as 

the refrigerant is under pressure.

• Never mix R-134a and R-12 refrigerants. They are in-

compatible and will cause severe damage to system 
components if mixed.

• Use an approved A/C service cart such as the Kent 

Moore J–39500-A to service the system. Recommended 
service carts are those capable of evacuation, recovery, 
recycling, and recharging of systems with R-134a.

• The only compressor lubricant oil that can used with 

this system is General Motors  PAG oil. Use of substi-
tutes will result in lubricant failure.

• Lubricate system fittings and o-rings with a 525 viscos-

ity refrigerant oil for leak proof connections.

• Do not heat containers of R-134a above 125° F (52° C).

• Never puncture or incinerate containers of R-134a.

• Avoid breathing R-134a. The gas will irritate the nose, 

throat, and lungs. In addition, because R-134a is heavier 
than air, it can displace oxygen in a confined and a 
poorly ventilated area. Be sure the work area is properly 
ventilated in case of accidental release into the nearby 
atmosphere.

 

A/C System Pressure Test

 

System pressure testing involves measuring suction and dis-
charge pressures with manifold gauge set J–39183-C, or with
the gauges contained in A/C service cart J–39500-A. One
gauge is for high side (discharge) pressures and one for low
side (suction) pressures. The gauges allow pressures to be
checked while the system is in operation.

On models where access to the service ports is limited, coupler
adapters J–39500-20A and J–39500-24A, will make gauge
hose connection easier.

 

Pressure Test Procedure

 

1.

Connect gauge hoses on service cart J–39500-A to service 
ports on suction and discharge lines (Figure 11-4). Red 
hose goes to high side (discharge) port and blue hose to 
low side (suction) port.

2.

Note pressure with engine not running and A/C system
inoperative. There should be approximately 50 psi to 70
psi in the system. If pressure is lower or zero, a system
leak exists. Add a small charge to the system. Then leak
test and repair as necessary before proceeding. 

3.

Start and run engine at 1200 rpm.

4.

Set A/C controls to maximum cooling and set blower to
highest speed.

5.

Verify that compressor clutch engages. If clutch fails to
engage, diagnose and repair before proceeding

6.

Record low and high side pressures. Depending on engine
speed and shop ambient temperature, low side pressure
will range from 18 to 35 psi (124 to 241 kPa) and high side
pressure from 176 to 320 psi. Ambient temperatures will
affect refrigerant pressures in the system. On cool days,
pressures are lower; on hot days pressures are higher.
Refer to system pressure comparison chart at end of this
section.

7.

If low and high side pressures are OK, check air
temperature at outlet duct closest to evaporator with
thermometer J–6742-03. Temperature should range from
33°F to 45°F  depending on ambient temperature. Be sure
thermometer tip is inserted into duct to a depth of at least
one inch (25 mm). 

8.

If low and high side pressures are incorrect and air duct
outlet temperatures are greater than specified, refer to
pressure test diagnosis charts for potential causes.

 

Figure 11-4:   Service Hose Connections at 

Compressor

00-S11-002

COMPRESSOR

BLUE SUCTION

(LOW SIDE) HOSE

RED DISCHARGE

(HIGH SIDE) HOSE

 

11-6

Heating/Ventilation/Air Conditioning (HVAC)

 

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A/C Servicing Precautions

 

There are precautions that should be followed when servicing
the A/C system. The precautions are necessary to avoid com-
ponent damage and personal injury.

• Wear eye protection when servicing the system. The re-

frigerant is under pressure and will cause injury if it 
contacts the eyes.

• Never perform system repairs until after the system has 

been fully discharged.

• Do not use refrigerant recovery, recycling, charging, 

and evacuation/discharge servicing equipment that does 
not meet SAE J–2210 standards.

• Never attempt to replace system components while the 

engine is running.

•  Avoid having R-134a contact the skin. The refrigerant 

can cause an injury similar to frostbite. Exercise care 
when handling R-134a.

• Do not allow any type of open flame near R-134a.

• Avoid breathing R-134a fumes. The refrigerant will 

cause eye, nose, throat, and lung irritation.

• Never mix R-12 and R-134a in the same system. The 

two refrigerants are 

 

not

 

 compatible. Mixing the two will 

result in failure of the compressor and other system 
components.

• Never use PAG oil from an unsealed container. The oil 

will quickly absorb moisture from the air if not sealed.

 

Recovering (Discharging) A/C System 
Refrigerant

 

1.

Shut engine off.

2.

Connect hoses from service cart J–39500-A to suction and
discharge service ports. Red hose goes to discharge side
and blue hose to suction side. Use adapter fittings J–
39500-20 and 24A if necessary. If manifold gauge set J–
39183-C is being used, connect center hose to a recovery
tank, or system.

 

NOTE: 

 

If both gauges indicate a zero reading, the system does

not contain any refrigerant. Add a small charge, leak test, and
make necessary repairs before proceeding.

3.

Begin recovery/discharge cycle as described in service
cart instructions.

4.

Recovery is complete when service cart gauges read
slightly below zero.

5.

Secure the service cart as described in the manufacturer’s
instructions.

 

Recycling System Refrigerant

 

The J–39500-A service cart (from Kent Moore), will recycle
R-134a refrigerant when necessary. The original recovered re-
frigerant is moved through a combination filtration/dryer unit
built into the cart. This unit removes impurities allowing
refrigerant reuse. Follow the manufacturer’s instructions care-
fully for the recycle process because incorrect use could result
in moisture in the refrigerant. The recycle process is accom-
plished automatically when the service cart is in evacuation
mode.

 

Evacuating the A/C System

 

CAUTION: 

 

Do not evacuate an A/C system that is not com-

pletely discharged. Check system pressures with a gauge set if
unsure about charge level.

 

The A/C system evacuation process involves applying 26-28
inches Hg to the A/C system for a minimum of 20 minutes.
The applied vacuum removes moisture. A vacuum pump built
into the service cart generates the necessary vacuum.

1.

Connect service cart J–39500-A to service ports.

2.

Discharge system.

3.

Connect vacuum pump to center hose on manifold if
gauge set J–39183-C is being used.

4.

Turn vacuum pump on, and open gauge valves.

 

NOTE: 

 

High side gauge should drop to zero or below. If not, a

blockage in A/C system is indicated. Deduct 1 in. vacuum from
maximum attainable reading for each 1000 ft elevation above
sea level.

5.

Evacuate unit until low pressure gauge reads 26-28 in. Hg.

6.

Turn vacuum pump off and allow system to sit
undisturbed for 15 min to  check for vacuum leaks. If
pressure rises, diagnose system leak.

7.

Continue evacuation for thirty minutes after correct gauge
reading of 26-28 in. Hg vacuum has been achieved.

8.

Turn gauge valves to closed position after evacuation is
complete.

9.

Turn off vacuum pump and disconnect center hose from
vacuum pump.