To the top of the document
Nubira-Lacetti
To Previous Page To Next Page
GMDE Start Page Load static TOC Load dynamic TOC Help?

SECTION 7B

MANUAL CONTROL HEATING, VENTILATION AND AIR CONDITIONING SYSTEM

Caution : Disconnect the negative battery cable before removing or installing any electrical unit or when a tool or equipment could easily come in contact with exposed electrical terminals. Disconnecting this cable will help prevent personal injury and damage to the vehicle. The ignition must also be in LOCK unless otherwise noted.

SPECIFICATIONS

General Specifications

Application
Unit
Description
Compressor
-
V5
Receiver-Dryer
-
AL R/DRYER
Refrigerant
Type
-
R-134a System
Capacity
g
640±20 (RHD : 690±20)
Refrigerant Oil in A/C System
Type
-
Union Carbide 488 PAG OIL
Capacity
cc (ml)
180
Evaporator Capacity (Airflow rate 8.7 kg/min)
Kcal/h
6000±10%

Fastener Tightening Specifications

Application
N•m
Lb-Ft
Lb-In
Pressure Transducer
7
-
62
Expansion Valve Stud Bolts
8
-
71
Liquid Pipe Support Clamp Bolts
4
-
35
Liquid Pipe Block-to-Receiver Dryer Retaining Nut
14
10
-
Liquid Pipe Block-to-Expansion Valve Retaining Nut
14
10
-
Refrigerant Discharge Hose Block-to-Condenser Retaining Nut
16
12
-
Refrigerant Discharge Hose Block-to-Compressor Retaining Nut
33
24
-
Evaporator Core Cover Screws
1.2
-
11
Heater Core Housing-to-Evaporator Housing Retaining Screws
1.2
-
11
Suction Hose Block-to-Compressor Retaining Nut
33
24
-
Suction Hose Support Clamp-to-Longitudinal Member Bolt
4
-
35
Suction Hose Support Clamp-to-Engine Bracket Bolt (1.4D, 1.6D only)
4
-
35
Suction Hose Support Clamp-to-Engine Bracket Bolt (1.8D, 2.0D only)
14
10
-
Suction Hose Block-to-Expansion Valve Retaining Nut
14
10
-
(Receiver Dryer) Band Clamp Bolt
5
-
44
Receiver Dryer-to-Condenser Pipe Block Bolt
5
-
44
Upper Compressor-to-Bracket Mounting Bolts (1.4D, 1.6D only)
25
18
-
Lower Compressor-to-Bracket Mounting Bolts (1.4D, 1.6D only)
45
33
-
Front Compressor-to-Bracket Mounting Bolts (1.8D, 2.0D only)
35
26
-
Rear Compressor-to-Bracket Mounting Bolts (1.8D, 2.0D only)
20
15
-
Condenser Mount Bolts
4
-
35
(Compressor) Clutch Plate and Hub Assembly Retaining Nut
17
13
-
(Compressor) Through Bolts
10
-
89

SPECIAL TOOLS

Special Tools Table


J5403
Display graphicTranslations of text in graphics


J-5403
Snap Ring Pliers

J6083
Display graphicTranslations of text in graphics


J-6083
Snap Ring Pliers

J8092
Display graphicTranslations of text in graphics


J-8092
Driver Handle

J84331
Display graphicTranslations of text in graphics


J-8433-1
Puller Crossbar

J84333
Display graphicTranslations of text in graphics


J-8433-3
Forcing Screw

J9398A
Display graphicTranslations of text in graphics


J-9398-A
Bearing Remover

J9481
Display graphicTranslations of text in graphics


J-9481
Bearing Installer

J95531
Display graphicTranslations of text in graphics


J-9553-1
O-Ring Remover

J9625A
Display graphicTranslations of text in graphics


J-9625-A
Pressure Testing Connector

J23128A
Display graphicTranslations of text in graphics


J-23128-A
Seal Seat Remover and Installer

J35372
Display graphicTranslations of text in graphics


J-35372
Support Block

J33011
Display graphicTranslations of text in graphics


J-33011
O-Ring Installer

J33013B
Display graphicTranslations of text in graphics


J-33013-B
Hub and Drive Plate Remover and Installer

J34993
Display graphicTranslations of text in graphics


J-34993
Cylinder Alignment Rods

J33017
Display graphicTranslations of text in graphics


J-33017
Pulley Rotor and Bearing Installer

J33019
Display graphicTranslations of text in graphics


J-33019
Bearing Staking Tool Set Includes:
J-33019-1
Bearing Staking Guide
J-33019-2
Bearing Staking Pin

J33020
Display graphicTranslations of text in graphics


J-33020
Pulley Puller

J34614
Display graphicTranslations of text in graphics


J-34614
Shaft Seal Protector

J33022
Display graphicTranslations of text in graphics


J-33022
Shaft Nut Socket

J33023A
Display graphicTranslations of text in graphics


J-33023-A
Puller Pilot

J33024
Display graphicTranslations of text in graphics


J-33024
Clutch Coil Installer Adapter

J33025
Display graphicTranslations of text in graphics


J-33025
Clutch Coil Puller Legs

J34992
Display graphicTranslations of text in graphics


J-34992
Compressor Holding Fixture

J33027
Display graphicTranslations of text in graphics


J-33027
Clutch Hub Holding Tool

SCHEMATIC AND ROUTING DIAGRAMS

A/C System - Typical


J6B17B01
Display graphicTranslations of text in graphics


  1. Compressor
  2. Condenser
  3. Receiver-Dryer
  4. Evaporator
  5. Expansion Valve

Manual Control A/C Diagram (1 of 2)


J5B17B01
Display graphicTranslations of text in graphics


Manual Control A/C Diagram (2 of 2)


J5B17B02
Display graphicTranslations of text in graphics


DIAGNOSIS

GENERAL DIAGNOSIS

Testing the Refrigerant System

If you suspect a problem in the refrigerant system, check for the following conditions:
  1. Check the outer surfaces of the radiator and the condenser cores to be sure that the airflow is not blocked by dirt, leaves, or other foreign material. Check between the condenser and the radiator, as well as all outer surfaces.
  2. Check for restrictions or kinks in the condenser core, the hoses, and the tubes.
  3. Check the operation of the blower fan.
  4. Check all the air ducts for leaks or restrictions. Low airflow rate may indicate a restricted evaporator core.
  5. Check for slippage of the compressor clutch.
  6. Check the drive belt tension.

Insufficient Cooling "Quick Check" Procedure

Perform the following "hand-feel" procedure to get a quick idea of whether the A/C system has the proper charge of Refrigerant-134a. The air temperature must be above 21°C (70°F) for most models.
  1. Warm up engine. Run the engine at idle.
  2. Open the hood and all the doors.
  3. Turn the A/C switch ON.
  4. Set the temperature control to the full cold position.
  5. Set the blower speed switch on the maximum speed setting.
  6. "Hand-feel" the temperature of the evaporator outlet pipe. The pipe should be cold.
  7. Check for other problems. Refer to "Testing the Refrigerant System" in this section.
  8. Leak check the system. Refer to "Leak Testing the Refrigerant System" in this section. If you find a leak, discharge the system and repair the leak as required. After completing the repair, evacuate the system and charge it.
  9. If there is no leak, refer to "Insufficient Cooling Diagnosis" in this section.

A/C Performance Test

RELATIVE HUMIDITY ( % )
AMBIENT AIR TEMPERATURE
LOW SIDE PRESSURE
ENGINE SPEED (RPM)
CENTER DUCT AIR TEMPERATURE
HIGH SIDE PRESSURE
.
°C
°F
Psi
Kpa
.
°C
°F
Psi
Kpa
.
21
70
26
179
.
7
45
160
1103
20
27
81
24
165
2000
8
46
212
1462
.
32
90
26
179
.
9
48
277
1910
.
38
100
33
228
.
14
57
333
2296
.
21
70
26
179
.
7
45
160
1103
30
27
81
24
165
2000
8
46
220
1517
.
32
90
27
186
.
10
50
283
1951
.
38
100
34
234
.
15
59
349
2406
.
21
70
26
179
.
8
46
162
1117
40
27
81
26
179
2000
9
48
227
1565
.
32
90
29
200
.
11
52
295
2034
.
38
100
37
255
.
17
63
364
2510
.
21
70
26
179
.
8
46
162
1117
50
27
81
26
179
2000
9
48
235
1620
.
32
90
32
221
.
13
55
304
2096
.
38
100
71
490
.
19
66
380
2620
.
21
70
27
186
.
8
46
165
1138
60
27
81
26
179
2000
9
48
246
1696
.
32
90
34
234
.
15
59
324
2234
.
38
100
44
303
.
22
72
393
2710
.
21
70
27
186
.
9
48
171
1179
70
27
81
28
193
2000
10
50
260
1793
.
32
90
36
248
.
16
61
330
2275
.
38
100
47
324
.
24
75
401
2765
.
21
70
27
186
.
9
48
178
1227
80
27
81
30
207
2000
12
54
266
1834
.
32
90
37
255
.
17
63
339
2337
.
21
70
27
186
.
9
48
178
1227
90
27
81
30
207
2000
12
54
272
1875
.
32
90
38
262
.
18
64
340
2344
* Test Conditions : Doors & hood opened, A/C ON, Recirculation mode, Full Cool with maximum Blower speed, No Sunlight, Wind velocity at 8km/h (5 mph).

Pressure-Temperature Relationship of R-134A

Temperature °C (°F)*
Pressure kPa (psi)*
Temperature °C (°F)*
Pressure kPa (psi)*
-8 (17.6)
113.1 (16.4)
9 (48.2)
296.2 (43.0)
-7 (19.4)
121.5 (17.6)
10 (50.0)
309.6 (44.9)
-6 (21.2)
130.2 (18.9)
15 (59.0)
383.7 (55.7)
-5 (23.0)
139.1 (20.2)
20 (68.0)
467.7 (67.8)
-4 (24.8)
148.4 (21.5)
25 (77.0)
567.5 (82.3)
-3 (26.6)
157.9 (22.9)
30 (86.0)
667.8 (96.9)
-2 (28.4)
167.6 (24.3)
35 (95.0)
785.6 (113.9)
-1 (30.2)
177.8 (25.8)
40 (104.0)
916.4 (133.0)
0 (32.0)
188.2 (27.3)
45 (113.0)
1 062.2 (154.0)
1 (33.8)
198.8 (28.8)
50 (122.0)
1 222.1 (177.2)
2 (35.6)
209.9 (30.4)
55 (131.0)
1 398.2 (202.8)
3 (37.4)
221.2 (32.1)
60 (140.0)
1 589.6 (230.5)
4 (39.2)
232.9 (33.8)
65 (149.0)
1 799.0 (260.9)
5 (41.0)
245.0 (35.5)
70 (158.0)
2 026.6 (293.9)
6 (42.8)
257.4 (37.3)
75 (167.0)
2 272.2 (329.5)
7 (44.6)
269.8 (39.1)
80 (176.0)
2 544.0 (369.0)
8 (46.4)
282.9 (41.0)
-
-
* All calculated values are rounded to one decimal place.
Evaporator Range: From -7 to 7°C (19.4 to 44.6°F), the temperatures represent the gas temperatures inside the coil and not on the coil surfaces. Add 2 to 6°C (4 to 11°F) to the coil and air-off temperatures.
Condenser Range: From 45 to 70°C (113°to 158°F), the temperatures are not ambient. Add 19 to 22°C (34 to 40°C) to the ambient temperatures for proper heat transfer. Then refer to the pressure chart.
Example:
32°C (90°F) Ambient temperature + 22°C (40°F) = 54°C (130°F)
Condenser temperature, which yields 1 379 kPa (200 psi), based on 50 km/h (31 mph) airflow.

Leak Testing Refrigerant System

Test for leaks whenever you suspect a refrigerant leak in the system. You should also test for leaks whenever you perform a service operation which results in disturbing the lines or the connections. Leaks are commonly found at the refrigerant fittings or at the connections. Leaks are commonly caused by the following problems:

Liquid Leak Detectors

Use a liquid leak detector solution on locations such as fittings. Apply the solution to the area in question with the swab that is supplied with the solution. Look for bubbles to appear. This will indicate the existence and the location of any leak.
For areas where this is not practical, such as sections of the evaporator and the condenser, an electronic leak detector is more useful.

Electronic Leak Detectors

Follow the manufacturer's instructions for calibration, operation, and maintenance of an electronic leak detector. Battery condition is especially important to the accuracy of a portable model. Set the detector to R-134a before beginning the test.

Notice : Electronic leak detectors are sensitive to windshield washing solutions, solvents and cleaners, and certain vehicle adhesives. Surfaces must be clean to prevent false readings. Make sure that all surfaces are dry to prevent damage to the detector.

General Testing Instructions

  1. Follow the entire path of the refrigerant system.
  2. Completely circle each joint at 25 to 50 mm (1 to 2 inches) per second.
  3. Hold the probe tip within 6 mm (1/4 inch) of the surface.
  4. Do not block the air intake.
  5. The audible tone changes from 1 to 2 clicks per second into a solid alarm if there is a leak. Adjust the balance control to maintain 1 to 2 clicks per second.
  6. Test all of the following areas, even after one leak has been confirmed:

Testing Service Ports/Access Valves

The sealing caps provide protection for the service ports. Make sure that these caps are not missing or loose. Always use the correct cap for each port.

Testing the Evaporator Core

Leaks in the evaporator core are difficult to find. Test the evaporator core using the following procedure:
  1. Run the blower fan at the maximum speed setting for at least 15 minutes.
  2. Turn the blower OFF.
  3. Wait for 10 minutes.
  4. Remove the blower motor resistor. Refer to Section 7A, Heating and Ventilation System.
  5. Insert the leak detector probe as close as possible to the evaporator core. The detector will indicate a leak with a solid alarm.
  6. Use a flashlight to search for refrigerant oil on the core surface.

Testing the Compressor Shaft Seal

  1. Blow shop air behind and in front of the compressor clutch/pulley for at least 15 seconds.
  2. Wait 1 to 2 minutes.
  3. Probe the area in front of the pulley. If the detector emits a solid alarm, there is a leak.

V5 SYSTEM AIR CONDITIONING DIAGNOSIS

Insufficient Cooling Diagnosis

Test Description

The numbers below refer to steps on the diagnostic table.
  1. See the Important below.
  2. See the Important below.

Important : Perform this test under garage conditions with the air temperature at 21-32°C (70-90°F), and no sun load. Follow this test carefully for accurate results.

Important : Perform this test exactly as described to obtain accurate results.

Step Action Value(s) Yes No
1
Record the customer's complaint.
Can you verify the customer's complaint?
-
Go to Step 2
System OK
2
  1. Check the A/C fuse.
  2. Check the blower fan operation.
  3. Check the engine cooling fan operation.
  4. Check the A/C compressor belt.
  5. Check the A/C condenser for restricted airflow.
  6. Check the clutch coil connection.
  7. Repair or replace any components as needed.
  8. Check the discharge air temperature with the A/C turned ON.
Is the discharge air temperature normal?
At least 7°C (12°F) below ambient air temperature
System OK
Go to Step 3
3
  1. Turn the ignition switch to LOCK.
  2. Connect the high- and the low-pressure gauges.
Are both pressures within the value specified?
69-345 kPa (10-50 psi)
Go to Step 4
Go to Step 5
4
  1. Check the A/C system for leaks.
  2. Repair any refrigerant leaks as needed.
  3. Recover, evacuate, and recharge the A/C system.
  4. Observe the two pressure gauges.
Are both pressures above the value specified?
345 kPa (50 psi)
Go to Step 7
-
5
Observe the two pressure gauges.
Are both pressures below the value specified?
69 kPa (10 psi)
Go to Step 6
Go to Step 7
6
  1. Add 0.45 kg (1 pound) of refrigerant R-134a.
  2. Check the A/C system for leaks.
  3. Repair any refrigerant leaks, as needed.
  4. Recover, evacuate, and recharge the A/C system.
  5. Observe the two pressure gauges.
Are both pressures above the value specified?
345 kPa (50 psi)
Go to Step 7
-
7
  1. Start the engine and allow it to run at idle.
  2. Set the A/C controls to the following positions:
    • The A/C switch to the ON.
    • The fresh air control switch to fresh air (indicator lamp OFF).
    • The blower motor to 4.
    • The temperature to full cold.
Does the A/C compressor clutch engage?
-
Go to Step 8
Go to Step 10
8
  1. Check for a knocking noise from the A/C compressor.
  2. Cycle the A/C compressor ON and OFF in order to verify the source of the noise.
Do you hear a loud knocking noise?
-
Go to Step 9
Go to Step 13
9
  1. Recover the A/C system refrigerant.
  2. Replace the A/C compressor.
  3. Evacuate and recharge the A/C system.
  4. Check the A/C system for leaks.
Is the compressor running normally?
-
Go to Step 13
-
10
  1. Turn the ignition switch to LOCK.
  2. Disconnect the A/C compressor clutch coil connector.
  3. Connect a jumper wire from ground to one A/C compressor clutch coil terminal.
  4. Connect a fused jumper wire from the positive battery terminal to the other A/C compressor clutch coil terminal.
Does the A/C clutch engage?
-
Go to Step 11
Go to Step 12
11
Repair the electrical circuit to the A/C compressor clutch coil.
Does the A/C clutch engage?
-
Go to Step 8
-
12
Replace the A/C compressor clutch coil.
Does the A/C clutch engage?
-
Go to Step 8
-
13
  1. Close all of the vehicle's windows and doors.
  2. Close all of the vehicle's windows and doors.
  3. Set the A/C controls to the following positions:
    • The A/C switch to the ON position.
    • The fresh air control switch to fresh air.
    • The blower motor to 4.
    • The temperature to full cold.
  4. Start the engine and allow it to run at idle for 5 minutes.
  5. Feel the evaporator inlet and outlet pipes.
Is there a noticeable difference in the temperature of the evaporator inlet and outlet pipes?
-
Go to Step 15
Go to Step 14
14
  1. Turn the ignition switch to LOCK.
  2. Recover the A/C system refrigerant.
  3. Examine the high-pressure pipe for an obstruction.
  4. Examine the expansion valve for an obstruction or a malfunction.
  5. Repair the obstruction or replace the expansion valve as needed.
  6. Evacuate and recharge the A/C system.
  7. Check the A/C system for leaks.
  8. Note the discharge air temperature with the A/C ON.
Is the discharge temperature normal?
At least 7°C (12°F) below ambient air temperature
Go to Step 15
Go to Step 13
15
  1. Record the low- and the high-side pressures after the A/C system has been operating for 5 minutes or more with the engine cooling fan ON.
  2. Locate the intersection of the low- and the high side pressures. Refer to "Low- and High-Side Pressure Relationship Chart" in this section.
Do the low- and the high-side pressures intersect in the white area of the chart?
-
System OK
Go to Step 16
16
Check the high- and the low-side pressures.
Do the low- and the high-side pressures intersect in the grey area of the chart?
-
Go to Step 17
Go to Step 20
17
Feel the liquid pipe between the condenser and the expansion valve.
Is the pipe cold?
-
Go to Step 18
Go to Step 19
18
  1. Examine the condenser for any restriction of the airflow.
  2. Check the cooling fans for proper operation.
  3. Remove the restriction or repair the fans, as required.
Is the pipe temperature normal now?
At least 7°C (12°F) below ambient air temperature
Go to Step 13
-
19
  1. Recover, evacuate, and recharge the A/C system.
  2. Check the A/C system for leaks.
Is the system free from leaks?
-
Go to Step 13
-
20
Observe the readings on the pressure gauges.
Are the A/C compressor high- and the low-side pressures within the specified value of each other?
207 kPa (30 psi)
Go to Step 21
Go to Step 26
21
  1. Run the engine at 3,000 rpm.
  2. Set the A/C controls to the following positions:
    • The A/C switch to the ON.
    • The fresh air control switch to fresh air.
    • The blower motor to 4.
    • The temperature to full cold.
  3. Close all of the vehicle's windows and doors.
  4. Turn the A/C switch ON and OFF every 20 seconds for 3 minutes.
Are the A/C compressor high- and the low-side pressures within the specified value of each other?
207 kPa (30 psi)
Go to Step 22
Go to Step 13
22
Observe the pressure rise on both gauges and the temperatures of both the compressor suction pipe and the discharge pipe.
Is the pressure rise on both gauges slow and the suction pipe warm with the discharge pipe very hot?
-
Go to Step 25
Go to Step 23
23
  1. Turn the ignition switch to LOCK.
  2. Make sure the compressor clutch is disengaged.
  3. Attempt to turn the clutch driver (not the pulley).
Can you turn the clutch driver freely by hand?
-
Go to Step 25
Go to Step 24
24
  1. Start the engine.
  2. Observe the low-side pressure gauge while running the engine between 3,000 and 3,800 rpm.
Does the low-side pressure rise rapidly?
-
Go to Step 32
Go to Step 25
25
  1. Recover the A/C system refrigerant.
  2. Replace the A/C compressor.
  3. Evacuate and recharge the A/C system.
Is the compressor functioning normally?
-
Go to Step 13
-
26
Check the low-side pressure.
Is the low-side pressure within the specified value?
172-241 kPa (25-35 psi)
Go to Step 27
Go to Step 32
27
Feel the high-side pipe leading up to the expansion valve connecting block.
Is the pipe cold before the connecting block?
-
Go to Step 28
Go to Step 29
28
  1. Check for a restriction in the high-side pipe before the expansion valve.
  2. Repair or replace the high-side pipe.
Is the pipe performing normally?
-
Go to Step 13
-
29
Add the specified amount of refrigerant to the A/C system.
Does the cooling performance improve?
0.40 kg (14 ounces)
Go to Step 30
Go to Step 31
30
  1. Check the A/C system for leaks.
  2. Repair any refrigerant leaks, as needed.
  3. Evacuate and recharge the A/C system.
  4. Check the A/C system for leaks.
Is the system free from leaks?
-
Go to Step 13
-
31
  1. Recover the refrigerant.
  2. Check the expansion valve for obstructions.
  3. Repair or replace the expansion valve, as required.
  4. Evacuate and recharge the system.
  5. Check the A/C system for leaks.
Is the system free from leaks?
-
Go to Step 13
-
32
  1. Run the engine for 5 minutes at 2,000 rpm.
  2. Set the A/C controls to the following positions:
    • The A/C switch to the ON position.
    • The fresh air control switch to recirculate (indicator lamp ON).
    • The blower motor to 1.
    • The temperature to full cold.
  3. Close all of the vehicle's windows and doors.
  4. Open the vehicle hood.
Is the low-side pressure within the specified value?
172-241 kPa (25-35 psi)
Go to Step 13
Go to Step 33
33
  1. Recover the A/C system refrigerant.
  2. Replace the A/C compressor control valve.
  3. Evacuate and recharge the A/C system.
  4. Check the A/C system for leaks.
Is the system free from leaks?
-
Go to Step 13
-

SYMPTOM DIAGNOSIS

Pressure Test Chart (R-134A System)

Test Results
Related Symptoms
Probable Cause
Remedy
Discharge (high) pressure abnormally high
After stopping the compressor, the pressure drops about 299 kPa (28 psi) quickly, then falls gradually.
Air in the system.
Recover, evacuate and recharge the system with the specified amount of refrigerant.
The condenser is excessively hot.
Excessive refrigerant in the system.
Recover, evacuate and recharge the system with the specified amount of refrigerant.
Reduced or no airflow through the condenser.
Condenser or the radiator fins are clogged.
Clean the condenser or the radiator fins.
.
Condenser or the radiator fan is not working properly.
Check the voltage and the fan rpm.
Check the fan direction.
Line to the condenser is excessively hot.
Restricted flow of refrigerant in the system.
Locate and repair the restriction.
Discharge pressure abnormally low
The condenser is not hot.
Insufficient refrigerant in the system.
Check the system for a leak.
Charge the system.
High and low pressures are balanced soon after stopping the compressor.
Faulty compressor pressure relief valve.
Repair or replace the compressor.
Low-side pressure is higher than normal.
Faulty compressor seal.
.
The outlet of the expansion valve is not frosted.
Faulty expansion valve.
Replace the expansion valve.
Low pressure gauge indicates vacuum.
Moisture in the system.
Recover, evacuate, and recharge the system.
Suction (low) pressure abnormally low
Condenser is not hot.
Insufficient refrigerant in the system.
Repair the leaks.
Recover, evacuate, and recharge the system.
The expansion valve is not frosted and the lowpressure line is not cold.
Faulty expansion valve.
Replace the expansion valve.
Low-Pressure gauge indicates a vacuum.
Frozen expansion valve.
.
Discharge temperature is low and the airflow from the vents is restricted.
Evaporator is frozen.
Clear the restricted evaporator case drain.
The expansion valve is frosted.
Expansion valve is clogged.
Clean or replace the expansion valve.
The receiver-dryer outlet is cool and the inlet is warm.
Receiver-dryer is clogged.
Replace the receiver-dryer.
Suction pressure abnormally high
Low-pressure hose and check joint are cooler than the temperature around the evaporator.
Expansion valve is opened for too long.
Replace the expansion valve.
.
Capillary tube is loose.
.
Suction pressure abnormally high
Suction pressure is lowered when the condenser is cooled by water.
Excessive refrigerant in the system.
Recover, evacuate, and recharge the system.
High and low pressure are equalized as soon as the compressor is stopped and both gauges fluctuate while the compressor is running.
Faulty gasket.
Repair or replace the compressor.
.
Faulty high-pressure valve. (V5 compressor only)
.
.
Foreign particles stuck in the high-pressure valve. (V5 compressor only)
.
Suction and discharge pressure abnormally high
Reduced airflow through the condenser.
Clogged condenser or radiator fins.
Clean the condenser and the radiator.
.
Radiator cooling fans working improperly.
Check the voltage and the radiator cooling fan rpm. Check the fan direction.
Condenser is excessively hot.
Excessive refrigerant in the system.
Recover, evacuate, and recharge the system.
Suction and discharge pressure abnormally low
Low-pressure hose and metal end areas are cooler than the evaporator.
Clogged or kinked low-pressure hose.
Repair or replace the low-pressure hose.
Temperature around the expansion valve is low compared to that around the receiver-dryer.
Clogged high-pressure line.
Repair or replace the high-pressure line.
Refrigerant leaks
The compressor clutch is dirty.
Leaking compressor shaft seal.
Repair or replace the compressor.
The compressor bolts are dirty.
Leaking around a compressor housing bolt.
Tighten the bolt(s) or replace the compressor.
The compressor gasket is wet with oil.
Leaking compressor gasket.
Repair or replace the compressor.

Low and High Side Pressure Relationship Chart


T3B17B82
Display graphicTranslations of text in graphics




To Previous Page To Next Page
© Copyright General Motors Chevrolet Europe. All rights reserved