| 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.
- Perform the Diagnostic System Check - Vehicle before using the Symptom Tables in order to verify that all of the following are true:
- Review the system operation in order to familiarize yourself with the system functions. Refer to Air Delivery Description and Operation
| • | There are no DTCs set. |
| • | The control module(s) can communicate via the serial data link. |
Visual/Physical Inspection
- Inspect for aftermarket devices which could affect the operation of the HVAC System. Refer to Checking Aftermarket Accessories .
- Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
- Verify the A/C compressor clutch turns freely and is not seized.
- Verify that the customer is using the correct key to enable personalization and is not inadvertently activating auxiliary HVAC controls.
- The following conditions may cause window fogging:
- Inspect the air distribution system for causes of reduced air flow:
| • | Wet carpet or mats |
| • | High humidity |
| • | Interior water leak |
| • | Blocked A/C evaporator drain tube |
| • | Maximum passenger capacity |
| • | Blocked body pressure relief valves |
| • | 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:
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. |
| ||||
The line to the condenser is excessively hot. | A restricted flow of refrigerant is in the system. | Locate and repair the restriction. |
Symptoms | Checks | Actions | ||||
|---|---|---|---|---|---|---|
The condenser is not hot. | Insufficient refrigerant is in 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. |
Symptoms | Checks | Actions | ||||
|---|---|---|---|---|---|---|
The condenser is not hot. | Insufficient refrigerant is in 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. |
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. |
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. |
| ||||
The condenser is excessively hot. | Excessive refrigerant is in the system. | Recover, evacuate, and recharge the system. |
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. |
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
- 70 kPa (10 psi)
- 138 kPa (20 psi)
- 207 kPa (30 psi)
- 276 kPa (40 psi)
- 345 kPa (50 psi)
- 414 kPa (60 psi)
- 483 kPa (70 psi)
- 552 kPa (80 psi)
- 621 kPa (90 psi)
- 690 kPa (100 psi)
High Side Pressure
- 690 kPa (100 psi)
- 1379 kPa (200 psi)
- 2069 kPa (300 psi)
- 2758 kPa (400 psi)
