GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 1998 🢒 Catera 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 TXV Air Conditioning (A/C) System Diagnosis
Table 1: Quick Look-Up Troubleshooting Table
Table 2: R-134a Temperature/Pressure Parameters

Step

Action

Value(s)

Yes

No

1
  1. Connect the scan tool.
  2. Read the scan tool for diagnostic codes.

Were diagnostic codes found?

--

Go to Step 19

Go to Step 2

2
  1. Turn the ignition switch to ON.
  2. Turn the blower speed from the following positions:
    3. • OFF to LO
    • MED LO to MED HI
    • HI
    • Then back to OFF
  3. Turn the ignition switch to LOCK.

Does the blower motor speed increase at each speed level when blower speed selector switch is turned to HI and then decreases as the switch is moved towards LO?

--

Go to Step 3

Go to Step 20

3

Inspect for a loose, damaged or missing compressor drive belt.

Is the action complete?

--

Go to Step 4

--

4

Inspect the engine coolant fan operation.

Is the action complete?

Refer to Engine Cooling Fan Description - Electric in Engine Cooling.

--

Go to Step 5

--

5
  1. Inspect the condenser for restricted air flow.
  2. Clean and/or repair as necessary.

Is the action complete?

--

Go to Step 6

--

6
  1. The ambient air temperature must be at least 16°C (60°F) before continuing to next step.
  2. Start the engine.
  3. Set the air mode to VENT.
  4. Set the blower speed to HI.
  5. Set the temperature mode to full COLD.
  6. Press the A/C switch to ON.

Does the compressor clutch engage?

--

Go to Step 7

Go to Step 9

7
  1. Closely monitor the compressor for unusual knocking or loud moaning noises and/or compressor drive belt slipping.
  2. Cycle the compressor clutch by pressing the A/C mode switch.
  3. Notice if compressor drive belt is slipping.

Is the compressor noise excessive?

--

Go to Step 21

Go to Step 8

8

Feel the liquid line between the condenser and the receiver/dryer. The line should feel warm to the touch.

Does the line feel cold?

--

Go to Step 22

Go to Step 12

9
  1. Turn the ignition switch to LOCK.
  2. Connect J 39500-B to the service parts,
  3. Inspect the system Lo and Hi pressures. Both pressures should be almost equal to each other.

Are both Lo and Hi pressures the same as or higher than specified value?

345 kPa (50 psi)

Go to Step 23

Go to Step 10

10

Monitor and compare Lo and Hi pressure readings.

Are both Lo and Hi pressures the same as or higher than specified value?

69345 kPa (1050 psi)

Go to Step 22

Go to Step 11

11

Inspect the system for refrigerant leaks.

Was the refrigerant leak found?

--

Go to Step 24

Go to Step 26

12

Feel the evaporator inlet pipe (small pipe) and evaporator outlet pipe at bulkhead. The evaporator inlet pipe should feel warm to the touch.

Does the inlet evaporator pipe feel colder than the evaporator outlet pipe?

--

Go to Step 13

Go to Step 16

13

Inspect the system for refrigerant leaks.

Was the refrigerant leak found?

--

Go to Step 24

Go to Step 14

14

Monitor compressor clutch cycle rate.

Was the compressor clutch cycle rate more than 8 cycles per minute?

--

Go to Step 25

Go to Step 15

15
  1. Start the engine.
  2. The air mode control knob set to VENT.
  3. Set the blower speed selector switch to HI.
  4. Set the temperature control knob all the way to COLD.
  5. Press the A/C mode to ON.
  6. Feel the evaporator inlet pipe (small pipe) and evaporator outlet pipe at bulkhead again. The evaporator inlet pipe should feel warm to the touch.

Does inlet evaporator pipe feel colder than the evaporator outlet pipe?

--

Go to Step 25

Go to Step 26

16
  1. Warm the engine to normal operating temperature.
  2. Feel the heater inlet hose at engine coolant control valve. It should feel warm but not as hot as engine coolant.

Does the heater inlet hose feel hot?

--

Go to Step 27

Go to Step 17

17

Inspect HI pressure.

Does the compressor engage within specified values?

196-3140 kPa (28-455 psi)

Go to Step 18

Go to Step 28

18
  1. Run compressor and monitor both clutch operation and HI pressure for five minutes.
  2. The compressor should disengage when HI pressure is outside specified values.

Did the compressor stay engaged outside specified values?

196-3140 kPa (28-455 psi)

Go to Step 28

Go to Step 29

19

Refer to Blower Motor Inoperative at Any Speed .

Is the action complete?

--

Go to Step 2

--

20

Refer to Blower Motor Inoperative at Any Speed for blower motor diagnosis.

Is the action complete?

--

Go to Step 3

--

21

Refer to Noise Diagnosis and determine the cause of excessive compressor noise.

Is the action complete?

--

Go to Step 8

--

22

Repair restriction in the HI side of the refrigerant system. Visually check for a line/pipe frosty spot to locate restriction.

Is the action complete?

--

Go to Step 12

--

23

Correct and/or repair code setting criteria.

Is the action complete?

--

Go to Step 7

--

24

Repair the refrigerant leak.

Is the action complete?

--

Go to Step 29

--

25
  1. Discharge the system.

    2. Refer to Refrigerant Recovery and Recharging

  2. Inspect for plugged expansion valve or HI side restriction.

Is the action complete?

--

Go to Step 29

--

26

Evacuate and recharge the system. Refer to Refrigerant Recovery and Recharging

Is the action complete?

--

Go to Step 29

--

27

Inspect the Heater Water Valve for a leaking or constantly-open.

Is the action complete?

--

--

--

28

Replace the A/C dual pressure switch.

Is the action complete?

--

Go to Step 17

--

29

Perform the A/C performance test.

Is the action complete?

--

System OK

--

Quick Look-Up Troubleshooting Table

Set controls to: NORMAL mode, HI blower, Lowest °C (°F) setting, Window open

Pressures as compared to a normal operating system

A/C Not Cold

HI-Side PSI

LOW-Side PSI

Related Symptoms

Undercharge

Low

Low

Compressor Grumbling Heard Inside of Vehicle

TXV Failure or Stuck Closed

Low

Low

Low-side Gauge Fluctuation

Low Side Restriction

Low

Normal to Low

Hose Kinked or Restricted

Engine Cooling Fan(s) Inoperative

High

High

Confirm Operation of Fan and Direction of Rotation

Overcharged

High

High

Compressor Cutting Out Due to High Pressure

Air in System

High

High

Compressor Cutting Out; Evaporator Freeze Up Possible

Restricted Airflow Across Condenser

High

High

Visually Inspect

TXV Stuck Open

High

High

Rapid Pressure Equalization on Shutdown; Slugging Noise Heard from Evaporator on Startup

Clutch/Relay/Electrical Failure

Low

High

Compressor Clutch Does Not Engage/High and Low-Side Pressures are Equal

Internal Compressor Failure

Low

High

No Change ON vs. OFF; High and Low-Side Pressures are equal

High-Side Restriction

Normal to High

Normal to Low

Feel High Side Hose/Piping for Abrupt Drop in Temperature

R-134a Temperature/Pressure Parameters

R-134a TEMPERATURE-PRESSURE

Temperature

 

Pressure

Temperature

 

Pressure

°C

°F

kPa

PSI

°C

°F

kPa

PSI

-9

16

 

106

15

38

100

 

857

124

-8

18

115

17

39

102

887

129

-7

20

124

18

40

104

917

133

-6

22

EVAP. RANGE

134

19

41

106

948

137

-4

24

144

21

42

108

980

142

-3

26

155

22

43

110

COND. RANGE

1012

147

-2

28

166

24

44

112

1045

152

-1

30

177

26

46

114

1079

157

0

32

188

27

47

116

1114

162

1

34

200

29

48

118

1149

167

2

36

212

31

49

120

1185

172

3

38

225

33

50

122

1222

177

4

40

238

35

51

124

1260

183

7

45

272

40

52

126

1298

188

10

50

310

45

53

128

1337

194

13

55

 

350

51

54

130

1377

200

16

60

392

57

57

135

1481

215

18

65

438

64

60

140

1590

231

21

70

487

71

63

145

1704

247

24

75

540

78

66

150

1823

264

27

80

609

88

68

155

1948

283

30

85

655

95

71

160

2079

301

32

90

718

104

74

165

2215

321

35

95

786

114

77

170

 

2358

342