Q: What precautions should be taken when servicing or replacing the receiver/drier and compressor in a Hyundai Sonata's air conditioning system?A: The receiver/drier should be serviced or replaced whenever the compressor is replaced. Have the refrigerant discharged by an automotive air conditioning technician. Disconnect the negative cable from the battery. Raise the vehicle and support it securely on jackstands. Remove the drivebelt from the compressor. Disconnect the electrical connector and the refrigerant lines. Seal the ends to prevent contamination. Unbolt the compressor and lower it from the vehicle. If a new or rebuilt compressor is being installed, follow the directions that came with the compressor regarding adding oil to the proper level prior to installation. Installation is the reverse of removal. Replace any 0-rings with new ones specifically made for the purpose and lubricate them with refrigerant oil. Tighten the mounting bolts evenly in several passes to avoid stressing the compressor case. Have the system evacuated, recharged and leak tested by the shop that discharged it.