For 1990-2009 cars

Table 1: | Discharge High Pressure Abnormally High
Table 2: | Discharge Pressure Abnormally Low
Table 3: | Suction Low Pressure Abnormally Low
Table 4: | Suction Pressure Abnormally High
Table 5: | Suction and Discharge Pressure Abnormally High Charge
Table 6: | Suction and Discharge Pressure Abnormally Low
Table 7: | Refrigerant Leaks

Important: The following steps must be completed before using the symptom tables.

1. Perform the Diagnostic System Check - Vehicle before using the Symptom Tables in order to verify that all of the following are true:

• | There are no DTCs set.

• | The control module(s) can communicate via the serial data link.

2. Review the system operation in order to familiarize yourself with the system functions. Refer to Air Delivery Description and Operation

### Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the HVAC System. Refer to Checking Aftermarket Accessories .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
3. Verify the A/C compressor clutch turns freely and is not seized.
4. Verify that the customer is using the correct key to enable personalization and is not inadvertently activating auxiliary HVAC controls.
5. The following conditions may cause window fogging:

• | Wet carpet or mats

• | High humidity

• | Interior water leak

• | Blocked A/C evaporator drain tube

• | Maximum passenger capacity

• | Blocked body pressure relief valves

6. Inspect the air distribution system for causes of reduced air flow:

• | Obstructed or dirty passenger compartment air filter, if equipped

• | Blocked or damaged air inlet or outlet vents

### Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

### Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

• | HVAC Compressor Clutch Does Not Engage

• | Blower Motor Malfunction

• | Too Hot in Vehicle

• | Too Cold in Vehicle

• | Air Delivery Improper

• | Improper Control Response

#### Discharge High Pressure Abnormally High

Symptoms | Checks | Actions
--- | --- | ---
After stopping the compressor, the pressure drops about 299 kPa (43 psi) quickly, then falls gradually. | Air is in the system. | Recover, evacuate, and recharge the system with the specified amount of refrigerant.
The condenser is excessively hot. | Excessive refrigerant is in the system. | Recover, evacuate, and recharge the system with the specified amount of refrigerant.
Reduced flow or no air flow through the condenser | The condenser or the radiator fins are clogged. | Clean the condenser or the radiator fins.
The condenser or the radiator fan is not working properly. |

• | Inspect the voltage and the fan RPM.

• | Verify the fan direction.

The line to the condenser is excessively hot. | A restricted flow of refrigerant is in the system. | Locate and repair the restriction.

#### Discharge Pressure Abnormally Low

Symptoms | Checks | Actions
--- | --- | ---
The condenser is not hot. | Insufficient refrigerant is in the system. |

• | Inspect the system for a leak.

• | Charge the system.

High and low pressures are balanced soon after stopping the compressor. | A faulty compressor pressure relief valve is present. | Repair or replace the compressor.
Low side pressure is higher than normal. | A faulty compressor seal is present.
The outlet of the expansion valve is not frosted. | A faulty expansion valve is present. | Replace the expansion valve.
The low pressure gage indicates vacuum. | Moisture is in the system. | Recover, evacuate, and recharge the system.

#### Suction Low Pressure Abnormally Low

Symptoms | Checks | Actions
--- | --- | ---
The condenser is not hot. | Insufficient refrigerant is in the system. |

• | Repair the leaks.

• | Recover, evacuate, and recharge the system.

The expansion valve is not frosted and the low pressure line is not cold. | A frozen expansion valve is present. | Replace the expansion valve.
The low pressure gage indicates a vacuum. | A faulty expansion valve is present.
The discharge temperature is low and the airflow from the vents is restricted. | The evaporator is frozen. | Clear the restricted evaporator case drain.
The expansion valve is frosted. | The expansion valve is clogged. | Clean or replace the expansion valve.
The receiver/dryer outlet is cool and the inlet is warm. | The receiver/dryer is clogged. | Replace the receiver/dryer.

#### Suction Pressure Abnormally High

Symptoms | Checks | Actions
--- | --- | ---
The low-pressure hose and the check joint are cooler than the temperature around the evaporator. | The expansion valve is opened for too long. | Replace the expansion valve.
The capillary tube is loose.
Suction pressure is lowered when the condenser is cooled by water. | Excessive refrigerant is in the system. | Recover, evacuate, and recharge the system.
High and low pressure are equalized as soon as the compressor is stopped and both gages fluctuate while the compressor is running. | A faulty gasket is present. | Repair or replace the compressor.
A faulty high-pressure valve is present.
Foreign particles are stuck in the high-pressure valve.

#### Suction and Discharge Pressure Abnormally High Charge

Symptoms | Checks | Actions
--- | --- | ---
Airflow through the condenser is reduced. | The condenser or the radiator fins are clogged. | Clean the condenser and the radiator.
The radiator cooling fans are not working properly. |

• | Inspect the voltage and the radiator cooling fan RPM.

• | Verify the fan direction.

The condenser is excessively hot. | Excessive refrigerant is in the system. | Recover, evacuate, and recharge the system.

#### Suction and Discharge Pressure Abnormally Low

Symptoms | Checks | Actions
--- | --- | ---
The low-pressure hose and metal end areas are cooler than the evaporator. | The low-pressure hose is clogged or kinked. | Repair or replace the low-pressure hose.
The temperature around the expansion valve is low compared to the temperature around the receiver/dryer. | The high pressure line is clogged. | Repair or replace the high-pressure line.

#### Refrigerant Leaks

Symptoms | Checks | Actions
--- | --- | ---
The compressor clutch is dirty. | The compressor shaft seal is leaking. | Repair or replace the compressor.
The compressor bolts are dirty. | Leaking occurs around a compressor housing bolt. | Tighten the bolts or replace the compressor.
The compressor gasket is wet with oil. | The compressor gasket is leaking. | Repair or replace the compressor.

### Low and High Side Pressure Relationship Chart

#### Low Side Pressure

1. 70 kPa (10 psi)
2. 138 kPa (20 psi)
3. 207 kPa (30 psi)
4. 276 kPa (40 psi)
5. 345 kPa (50 psi)
6. 414 kPa (60 psi)
7. 483 kPa (70 psi)
8. 552 kPa (80 psi)
9. 621 kPa (90 psi)
10. 690 kPa (100 psi)

#### High Side Pressure

1. 690 kPa (100 psi)
2. 1379 kPa (200 psi)
3. 2069 kPa (300 psi)
4. 2758 kPa (400 psi)