The A/C system uses an A/C refrigerant pressure sensor mounted in the high pressure side of the A/C refrigerant system. The A/C pressure sensor responds to changes in the A/C refrigerant pressure. The PCM uses this information to turn ON the engine coolant fans when the A/C pressure is too high. The PCM also uses the information to disengage the A/C compressor when the A/C refrigerant pressure is excessively high or low. The PCM supplies the sensor with a 5 volt reference and a ground. The sensor returns a signal voltage relative to A/C refrigerant pressures. The PCM monitors the A/C pressure sensor to detect signal voltages outside of the possible range of the sensor. When the PCM detects an A/C pressure signal that is excessively high, DTC P0533 will set.
| • | The engine is running. | 
| • | The A/C has been requested. | 
| • | The A/C pressure sensor signal is more than 4.9 volts. | 
| • | The condition exists for 3 seconds. | 
| • | The PCM will not illuminate the malfunction indicator lamp (MIL). | 
| • | The PCM will store the conditions present when the DTC set as Failure Records data only. | 
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. | 
| • | The DTC can be cleared by using the scan tool Clear DTC Information function. | 
If the condition is intermittent, refer to Intermittent Conditions .
Step  | Action  | Values  | Yes  | No  | 
|---|---|---|---|---|
1  | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?  | --  | ||
2  | 
 Does the scan tool indicate a voltage above the specified value?  | 3.5V  | ||
3  | Is DTC P1639 also set?  | --  | ||
4  | 
 Does the scan tool indicate that DTC P0533 failed last test?  | --  | Go to Diagnostic Aids  | |
5  | 
 Does the scan tool a voltage near the specified value?  | 0V  | ||
6  | 
 Is the test lamp ON?  | --  | ||
7  | 
 Did you find and correct the condition?  | --  | ||
8  | 
 Did you find and correct the condition?  | --  | ||
9  | 
 Did you find and correct the condition?  | --  | ||
10  | Replace the A/C pressure sensor. Refer to Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement in Heating, Ventilation and Air Conditioning. Is the action complete?  | --  | --  | |
11  | 
 Important: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete?  | --  | --  | |
12  | 
 Does the scan tool indicate that DTC P0533 passed?  | --  | System OK  |