Refrigerant Oil: Service and Repair

Filling and adjusting compressor oil
The A/C system is filled with 150 ml of compressor oil for the A/C pump (petroleum) and 295 ml for A/C pump (diesel). A certain amount of compressor oil is always lost in when draining refrigerant and when changing components. This amount must be topped up again so that the system operation will not be adversely affected.

Filling of compressor oil should be done on the compressor high-pressure side. The compressor oil is supplied in tubes of 20 ml. The tables below indicate how much compressor oil that is lost in conjunction with various types of service work on the A/C system.

A/C pump, petroleum

Reason for loss of oil Amount of oil lost
Draining of refrigerant 15 ml
Ruptured A/C hose 30 ml
Replacing hose 15 ml
Replacing condenser 30 ml
Replacing evaporator 30 ml
Replacing receiver 30 ml
Replacing expansion valve 15 ml
Replacing compressor* 50 ml*

* Note that the new compressor contains 150 ml of oil when delivered. In order to avoid getting too much oil in the A/C system, and thereby reducing cooling performance, the oil must be drained before the compressor is fitted. How much needs to be drained depends on how much oil that has been lost in conjunction with any eventual other component replacements. The A/C system must always contain 150 ml of compressor oil.

If only the compressor is to be replaced, 85 ml of oil should be drained from the new compressor (150 - 50 - 15 = 85). If the receiver is also replaced, only 55 ml should be drained from the compressor, according to the following calculation:

150 ml (in new compressor)
- 15 ml (lost when draining)
- 30 ml (lost when replacing receiver)
- 50 ml (lost when replacing compressor)
55 ml (drained from the new compressor)

A/C pump, diesel

Reason for loss of oil Amount of oil lost
Draining of refrigerant 30 ml
Ruptured A/C hose 60 ml
Replacing hose 30 ml
Replacing condenser 60 ml
Replacing evaporator 60 ml
Replacing receiver 60 ml
Replacing expansion valve 30 ml
Replacing compressor* 100 ml*

* Note that the new compressor contains 295 ml of oil when delivered. In order to avoid getting too much oil in the A/C system, and thereby reducing cooling performance, the oil must be drained before the compressor is fitted. How much needs to be drained depends on how much oil that has been lost in conjunction with any eventual other component replacements. The A/C system must always contain 295 ml of compressor oil.

If only the compressor is to be replaced, 165 ml of oil should be drained from the new compressor (295 - 100 - 30 = 165). If the receiver is also replaced, only 105 ml should be drained from the compressor, according to the following calculation:

295 ml (in new compressor)
- 30 ml (lost when draining)
- 60 ml (lost when replacing receiver)
- 100 ml (lost when replacing compressor)
105 ml (drained from the new compressor)