In automotive air conditioning systems, compressor oil does much more than just lubrication. It plays a vital role in sealing, cooling, and moisture absorption within the circuit. Using the wrong oil type or operating with insufficient oil can lead to complete compressor failure.
Key properties of proper AC oil:
- Refrigerant compatibility: PAG oils (e.g., PAG46, PAG100) are compatible with R134a. For newer refrigerants like R1234yf, POE or PAO oils are required.
- Correct viscosity grade: Viscosity should match the compressor design and the climate conditions.
- Chemical stability: The oil must resist breakdown under heat, moisture, and pressure over time.
Signs of oil issues in an AC system:
- Unusual compressor noise, especially when the clutch engages
- Weak cooling performance
- Leaks at seals, O-rings, or hose joints
Professional tip: When replacing the compressor or recharging refrigerant, always evacuate, flush, and refill the system with the correct oil using an automated A/C service machine to ensure proper operation and system longevity.