Hummer H1 (2002+). Manual — part 183

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

®

05745159

A/C Pressure Test Diagnosis

Condition

Possible Cause

Correction

Low Side High
High Side High
(Discharge Air Warm -
Discharge Line Warm to
Hot)

1.

Condenser fins obstructed or distorted.

1.

Clear obstruction with water spray and
compressed air. Straighten distorted fins
with tool J–36847 or equivalent.

2.

System overcharged.

2.

Recover excess charge with A/C service
cart J–39500-A.

3.

Air in system.

3.

Evacuate and recharge system.

4.

Expansion valve failed.

4.

Replace valve.

5.

Condenser restricted.

5.

Replace condenser. Evacuate and recharge
system.

6.

Compressor drive belt slipping.

6.

Replace belt or belt tensioner as needed.

Low Side High
High Side High
(Discharge Air Slightly
Cool - Discharge Line
Cool)

1.

Air and moisture in system.

1.

Discharge system. Replace receiver/dryer
and evacuate - recharge system.

2.

Leak at A/C line of 1/2 ounce or less.

2.

Locate with D-Tek leak tester. Recharge
system and verify proper operation.

Low Side Low
High Side Low

1.

System low on refrigerant.

1.

Add refrigerant and leak test system. Cor-
rect leak source and recharge as needed.

NOTE:

If leak was large, check compres-

sor oil level also and correct as needed.

2.

Expansion valve failed.

2. Replace valve, then evacuate and recharge
system.

Low Side High
High Side Low

1.

Internal leak in compressor

1.

Replace compressor and evacuate -
recharge system.

2.

Expansion

valve

failure.

2.

Discharge system. Replace valve and
recharge system.

3.

Drivebelt slip.

3.

Replace belt.

Low Side Low
High Side High

1.

Expansion valve failed.

1.

Discharge system. Replace valve and
recharge.

2.

A/C hose constricted, plugged.

2.

Check hose for kinks. Replace hose if
plugged and evacuate - recharge system.

3.

Receiver/Dryer restricted or has failed.

3.

Evacuate system. Replace receiver/dryer
and recharge system.

4.

Condenser problem (blocked, damaged).

4.

Evacuate system. Replace condenser and
recharge system.

Low Side and High Side
Normal But Cooling is
Inadequate

1.

Air and/or moisture in system.

1.

Leak test system. Repair leaks if neces-
sary. If leaks are not evident, evacuate and
recharge system.

2.

Receiver/Dryer fault.

2.

Evacuate system, replace receiver/dryer
and recharge system.

11-12

Heating/Ventilation/Air Conditioning (HVAC)

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®

Compressor Diagnosis

Condition

Possible Cause

Correction

Compressor Noise

1.

System overcharge.

1.

Recover all R-134a with J–39500-A ser-
vice cart and recharge with proper charge.

2.

Drivebelt problem.

2.

Replace belt if worn, frayed, cut or torn.

3.

Compressor clutch fault.

3.

Replace core or pulley bearing as needed.

4.

Compressor

internal

fault.

4.

Replace compressor if pressure test
indicates worn, inoperative condition.

Compressor Does Not Engage

1.

System fuse blown.

1.

Replace fuse. Check circuit for shorts,
ground.

2.

Clutch wires damaged.

2.

Repair wires.

3.

Pressure cycling clutch, or A/C cutout
switch fault.

3.

Replace switch(s) as needed.

4.

Compressor

clutch

failure.

4.

Replace clutch core and/or pulley as
needed.

5.

Compressor seized.

5.

Replace compressor.

6.

High engine coolant temperature trig-
gering A/C cutout switch.

6.

Let engine cool down and fix engine
cooling system problem first.

Compressor Engages but Cool-
ing is Inadequate

1.

A/C duct restrictions, loose connec-
tions.

1.

Repair as needed.

2.

System leaks (high side pressure
below 50 psi (345 kPa)).

2.

Check for leaks with D-Tek tool and
repair as needed.

3.

Expansion valve inoperative.

3.

Replace valve.

4.

Receiver/Dryer fault.

4.

Replace

5.

Condenser fault.

5.

Replace condenser.

6.

Compressor internal wear.

6.

Replace compressor if pressure indicates
internal wear or damage.

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Heating/Ventilation/Air Conditioning (HVAC) 11-13

®

05745159

SPECIFICATIONS

System refrigerant — R-134a

Compressor oil — PAG (polyalkaline glycol)

Refrigerant capacity — 3 lbs.2oz.

Compressor type — Harrison HT6

*Low and high side pressures are affected by relative humid-
ity. Greater humidity will cause higher pressures

A/C System Test Pressures

Ambient Temperature

Low Side Pressure Range*

High Side Pressure Range*

F°

C°

Psi

kPa

Psi

kPa

70

21

10-32

69-221

112-270

772-1861

75

24

12-33

83-228

120-280

827-1930

80

27

17-34

117-234

131-310

903-2137

85

29

18-35

124-241

185-325

1276-2172

90

32

19-47

131-324

210-330

1448-2275

95

35

21-47

145-324

225-350

1551-2413

100

38

28-51

193-352

240-370

1655-2551

110

43

30-55

207-379

255-390

1758-2689

11-14

Heating/Ventilation/Air Conditioning (HVAC)

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®

R-134a Pressure-to-Temperature Relationship Chart (with Engine OFF)

Psi

Temp (°F)

R-134a

Psi

Temp (°F)

R-134a

Psi

Temp (°F)

R-134a

Psi

Temp (°F)

R-134a

0

-14.7

25

29.3

70

69.6

200

130.1

1

-12.1

26

30.5

75

72.9

210

133.5

2

-9.6

27

31.7

80

76.1

220

136.7

3

-7.2

28

32.9

85

79.2

230

139.8

4

-4.9

29

34.0

90

82.2

240

142.9

5

-2.7

30

35.1

95

85.0

250

145.9

6

-0.6

32

37.4

100

87.8

260

148.8

7

1.4

34

39.5

105

90.5

270

151.6

8

3.4

36

41.6

110

93.1

280

154.3

9

5.3

38

43.6

115

95.6

290

157.0

10

7.1

40

45.6

120

98.0

300

159.6

11

8.9

42

47.4

125

100.4

310

162.2

12

10.6

44

49.2

130

102.7

320

164.7

13

12.3

46

51.0

135

104.9

330

167.2

14

13.9

48

52.8

140

107.1

340

169.6

15

15.4

50

54.5

145

109.3

350

171.9

16

17.0

52

56.4

150

111.4

360

174.2

17

18.5

54

57.8

155

113.3

370

176.5

18

19.9

56

59.3

160

115.4

380

178.7

19

21.4

58

60.8

165

117.4

390

180.7

20

22.8

60

62.4

170

119.3

400

183.1

21

24.1

62

63.9

175

121.2

-

-

22

25.5

64

65.4

180

123.0

-

-

23

26.8

66

66.8

185

124.8

-

-

24

28.0

68

68.2

190

126.6

-

-