Refrigerant (R134A)

Volvo introduced refrigerant R134a in the 940 and 960 from the 1993 models on. Only this refrigerant may be used in A/C systems for which it is specified. R134a contains only fluorine, unlike R12, which is a chlorofluorocarbon (CFC). The car is equipped with a sticker (11) in the engine compartment and a yellow tag around the service valve (9) to indicate that the system contains the new medium.

The components (1-9) have been modified and adapted especially for R134a in the 1993 models. These components are described in further detail on the following page.

Two new drainage and recycling units (RHS 850 and RHS 650) have been developed in conjunction with the introduction of the new refrigerant. The operation of these units is described on pages 248 and 262 respectively. The RHS 850 and RHS 650 units may be used to drain, purify and recover the refrigerant, in addition to vacuum-pumping, testing and refilling the A/C system in the car.




1. Compressor
2. Condenser
3. Safety switch
4. High-pressure switch, blower, high speed
5. High-pressure switch, blower, low speed
6. Expansion tube (orifice)
7. Low-pressure ("pressostat")
8. Air receiver (dryer)
9. Service valve


New and modified components introduced with refrigerant R134a
- Since R134a operates at a different pressure and temperature than R12, the expansion tube and all pressure switches are new.
- The compressors have been modified internally using materials of different types to ensure satisfactory lubrication.
- A special drying agent is used in the air receiver.
- On 4-cylinder and diesel models, the reciprocating compressors have been replaced by the rotary vane type (1), in which the increase in pressure is achieved by a progressive decrease in the volume between the vanes as the rotor rotates between the inlet and outlet ports. The noise from this type of compressor is lower and somewhat different compared with the reciprocating type.
- All compressor variants are equipped with a temperature switch (10), which interrupts the supply if the unit becomes overheated, for example, due to refrigerant leakage. The supply is restored when the temperature returns to normal.


- The service valve (9) is of a new type with an SAE standard connection. (SAE stands for Society of Automotive Engineers.)
- The evaporator (12) is the same as before.

To eliminate the risk of installing earlier components in a new system, the pressure switch and air receiver connection threads have been altered from Imperial to metric sizes.

Under no circumstances may an A/C system using R134a be filled with the earlier R12 refrigerant. Furthermore, only PAG (PolyAlkylene Glycol) oil may be used with R134a. Two different PAG oils are available depending on the make of compressor installed in the car. When filling with oil, it is extremely important that the correct grade for the particular compressor is used. The PAG oils may not be interchanged or mixed. The correct PAG oils for the various compressors using refrigerant R134a are shown in the table below.

The following will occur if refrigerant R12 is used in a system designed for R134a:
A. The compressor will overheat and seize.
B. The working temperature will become excessive, leading to failure of hoses and seals.

Similarly, a system designed for R12 will suffer damage if filled with R134a or with PAG oil.