BMW X3 Service & Repair Manual: Refrigeration oil

2.0 REFRIGERATION OIL

OIL USED IN FREONÂ-CHARGED SYSTEMS

A mineral-based oil is used. The oil level in the compressor must be checked before filling an air conditioner with refrigerant. It can be checked only if the system is without refrigerant.

Always check the oil level each time a new system is filled with Freon R12 or after repairs. The oil level is very important for the entire air conditioning system. Part of the oil (approx. 25% depending on amount of refrigerant) is mixed with the refrigerant and is continuously circulated in the system. This oil lubricates the moving parts of the system, such as the expansion valve and compressor.

OIL USED IN R-134A-CHARGED SYSTEMS

A synthetic oil is used, which is totally different than the mineral-based oils used in Freon R12 systems.

R-134a systems require Polyalkylene Glycol lubricants, often referred to as "PAG" oil. Use of R-12 compressor oil in R-134a systems will cause the compressor to seize and fail. The R-12 mineral oil does not stay in solution in R-134a. In addition, R-134a compressor should not be used in an R-12 system. Long term damage and corrosion will result.

The GREEN R-134a system labels, usually located near the top side of the fan shroud in the engine compartment, will display the refrigerant requirement for R-134a systems. An example is illustrated.

R-12 systems will have a BLACK label in a similar location.

PAG oil should only be stored in its original container, and sealed as tightly as possible. PAG oil is totally devoid of moisture when packaged, and will absorb moisture readily (hygroscopic) if exposed to the atmosphere, rendering it useless. Dispose of all extracted lubricants from A/C systems. Never reuse old compressor oil. Contaminated PAG oil should never be added to the air-conditioning system, and old PAG oil is typically contaminated with moisture. R-134a is even more sensitive to moisture contamination than R-12 systems, and because of the desiccant material change PAG oil may be obtained from BMW of North America.

BMW Part No. 82 11 1 468 042.

3.0 AIR CONDITIONING UNIT DISINFECTANTS

A musty odor may be detected in the vehicle, particularly when the air conditioner is first switched on.

This is caused by microorganisms growing on the evaporator from moisture condensation.

A disinfectant can be applied to the air conditioning system:

4.0 AIR CONDITIONER REFRIGERATION/OIL FILL CAPACITIES

Reference information for servicing BMW Air Conditioning systems is listed on the chart on page 6. Please refer to this chart when evacuating/recharging BMW A/C systems.

Note that some 1993 Model Year early production R-134a equipped vehicles have under-hood labels that specify higher charge values than those specified in the chart. Testing has confirmed that the values given are the optimum fill capacities. Consult the chart before refilling. Labels with the lower refrigerant charge amount specified on the chart have been phased into production as of 11/92.

When performing repairs to the A/C system that require recharging, only the specifications given in this chart should be used, as well as the label part numbers, as appropriate (see chart). However, inadvertent refrigerant charging up to the fill capacity given on an "original" ('93 MY production prior to 11/92) under-hood label will not cause any problems.

Refrigerant, Special Features, Production Range, Fill Capacity g (lbs), Fill Capacity ml (oz), BMW P/N

AIR CONDITIONER REFRIGERATION/OIL FILL CAPACITIES CHART

(1) The Modine condenser was used in many E36 vehicles over the production range 9/91 - 3/92. This condenser has a smaller volume, and the A/C system must be charged accordingly.
(2) Production start of 1993 MY E34/S38 (M5) 9/92; E32/M70 (750iL) 11/92.
(3) R-134a, the environmentally friendly air conditioning refrigerant, was introduced to the U.S. market beginning with 3/92 production E32/M30 (735i/iL) vehicles.
(4) Labels reflecting the proper charging volumes given on this chart are available form BMW Parts.
These may be used in place of the original equipment labels on '93 model year vehicles produced before 11/92.
(5) All vehicles equipped with R-134a refrigerant require special PAG lubricant..
(6) Nippon Denso
(7) Seiko Seiki