Test No. 20: Refrigerant System
- Test A/C system performance. See A/C SYSTEM PERFORMANCE . If system pressures are not as specified, diagnose and repair system accordingly. See REFRIGERANT SYSTEM DIAGNOSIS DIRECTORY table. If high pressure and low pressure readings are the same, check for improper A/C compressor operation. See TEST NO. 21: VANE NOISE .
- Check for clogged or damaged condenser fins. Repair as necessary. Ensure there is sufficient refrigerant in system. If condenser fins are not clogged or damaged, check if there is too much refrigerant in system. Adjust as necessary.
- Perform leak test. If leak or oil stains exist, repair as necessary. If leak and oil stains are not present, check for insufficient refrigerant caused by occasional leakage. Correct refrigerant level if necessary.
- Check if heat-sensing tube is properly positioned and securely connected to evaporator outlet pipe. Re-install tube if necessary. If tube is properly positioned and secured, replace expansion valve.
- Turn blower switch off and wait about 10 minutes. Place blower switch in fourth speed position. Check pressure readings immediately after compressor is shut off. If pressure readings are normal, expansion valve is clogged due to frozen moisture. Replace receiver-drier.
- If pressure readings are not normal, check if heat-sensing tube is properly positioned. Re-install tube if necessary. If tube is properly positioned, replace expansion valve.
REFRIGERANT SYSTEM DIAGNOSIS DIRECTORY
| High Pressure Reading |
Low Pressure Reading |
Go To |
| More Than Spec. |
More Than Spec. |
Step 2 |
| Less Than Spec. |
Less Than Spec. |
Step 3 |
|
|
Step 4 |
| ..... |
Negative Pressure |
Step 5 |