When an automotive air conditioning system appears to function properly but the compressor oil, visible at the pressure ports, looks black or contaminated, it indicates internal degradation known as “Black Death.” This issue results from metallic particles or residues caused by compressor wear or chemical reactions between the refrigerant and the oil. If not addressed promptly, it can spread quickly and damage other components.
Below are the recommended steps to resolve this problem:
1. Depressurize and Disconnect the System
- Completely depressurize the system.
- Disconnect components such as the compressor, condenser, evaporator, and hoses.
- This step prevents accidents and facilitates thorough cleaning.
2. Clean the Components
- Use a specialized cleaning solution and compressed air equipment.
- Clean each component individually, including the evaporator, condenser, and hoses.
- Perform this procedure in a well-ventilated area to avoid exposure to harmful chemicals.
3. Replace the Receiver Drier or Desiccant Filter
- Replace the drier filter, as it traps moisture and particles.
- A clean filter prevents contaminants from circulating back into the system.
4. Replace Seals
- When reassembling the system, use new seals.
- This ensures an optimal seal and prevents future refrigerant leaks.
5. Replace Compressor Oil
- Remove all oil from the compressor crankcase and replace it with new PH-type oil.
- Add the same quantity of oil that was removed.
- If the compressor has a screw or plug, use this point to add the oil; otherwise, add it through the thicker pipe while slowly turning the shaft to lubricate the internal components.
- Avoid exposing PH oil to the environment to prevent moisture absorption.
6. Check for Leaks
- Reassemble the system while keeping it turned off.
- Pressurize the system with nitrogen to 200 PSI (pounds per square inch).
- Leave the system pressurized for several minutes and verify that the pressure remains stable, indicating no leaks.
7. Vacuum the System
- If no leaks are detected, remove the nitrogen and vacuum the system until it reaches 500 microns of mercury.
8. Add Additional Oil and Refrigerant
- Add an amount of oil equivalent to what was removed from the compressor.
- Recharge the refrigerant following the manufacturer’s specifications, ensuring a low-pressure reading close to 35 PSI with the engine idling.
9. Perform a Final System Check
- Turn on the air conditioning and verify that it operates without strange noises or irregularities.
- If any additional issues are detected, conduct a more detailed inspection.
