how much oil does my car ac system need ?
The amount of auto air conditioning system oil and the correct type for the vehicle is vital to the life of the a/c compressor. Proper lubrication is a must for ac compressor long life. When the a/c compressor is operated ,oil gradually leaves the compressor, and the oil is circulated through the entire ac system together with the refrigerant. After the air conditioning system is operated for the first time an oil balanced condition is reached in which a certain amount of oil is retained in the compressor and a certain amount is re-circulated through the ac system components with different amounts of oil depositing in them . If a component of the system is replaced after the system has been operated, we need to compensate for this by adding oil to the new replacement ac part.
HOW AN OVERCHARGE/UNDERCHARGE A/C OIL CONDITION AFFECT THE A/C SYSTEM?
Too much oil in the a/c system could result in extremely high head pressures which will cause poor air conditioning performance and premature wear and failure of the hvac compressor. If there is a surplus of oil in the system, too much oil circulates with the refrigerant ,causing the cooling capacity of the system to be reduced and the compressor head pressure to increase. Too little oil results in poor lubrication of the compressor and an increase in the heat of compression which shorten the life of the ac compressor.
OIL BALANCING AN AC SYSTEM
When there has been excessive leakage of refrigerant, or it is necessary to replace a component of the refrigeration system oil balancing is necessary to assure that the total oil charge in the system is the correct one after the leak has been repaired or the new ac part is installed in the car.
HOW TO OIL BALANCE MY CAR AC SYSTEM
The recommended procedure step by step
- Measure the oil recovered from the system while recovering the refrigerant prior to part replacement
- Drain and measure the oil left in the old part
- Drain the new part(if factory oil-prefilled)
- Refill the new part with the same amount of oil removed from the old part and the amount of oil recovered from the system
WHAT TYPE OF OIL ACCORDING TO TYPE OF REFRIGERANT R-12 R-1234YF AND R-134a
The refrigerant oil required by the automotive ac system depends on a number of factors ,but it is primarily dictated by the type of refrigerant used in the system.R-12 car systems used a mineral oil. Mineral oil mixes well with R-12 without breaking down and losing its lubrication characteristics. Mineral oil however cannot be used to lubricate ac systems with R-134a refrigerant.R-134 systems require a different synthetic oil,polyalkylene glycol (PAG).There are different blends of PAG and POE oil; always use the recommended by the vehicle manufacturer or the replacement part manufacturer.
The lubricant oil used in automotive air-conditioning systems is a non-foaming, sulfur free grade specially formulated for use in cars a/c systems. New refrigerants like R-1234yf might use PAG 46 and are backwards compatible for use with R-134a systems, but the R-134a old PAG 46 oils are not forward compatible with R-1234yf systems.
OIL RECHARGE AMOUNTS
| REFRIGERANT OIL Recommended PAG oil: DENSO ND-OIL 8 |
| Add the recommend refrigerant oil in the amount listed if you replace any of the following parts: |
| A/C condenser(including receive Dryer. | 25 mL (5/6 fl oz) |
| Evaporator | 40 mL (1 1/3 fl oz) |
| Line or hose | 10 mL (1/3 fl oz) |
| Receiver/dryer | 10 mL (1/3 fl oz) |
| Leakage repair | 25 mL (5/6 fl oz) |
| A/C compressor | For A/C compressor replacement, subtract the volume of oil drained from the removed A/C compressor from 82 mL (2 3/4 fl oz), and drain the calculated volume of oil from the new A/C compressor: 82 mL (2 3/4 fl oz) － Volume of removed A/C compressor = Volume to drain from new A/C compressor. NOTE: Even if no oil is drained from the removed A/C compressor, do not drain more than 50 mL (1 2/3 fl oz) from the new A/C compressor. |
