Procedure
The following procedure replaces the steps listed in the installation instructions included with the kit. The information has been revised and expanded for clarity:1. Safety Precautions when Handling Refrigerant
A/C systems are filled with refrigerant under pressure. Safety precautions must be followed when working with these systems. Refer to S.I. 64 10 92 (3536) for a list of procedures relating to safe refrigerant handling.
2. Discharging and Removing Mineral Oil from the A/C System
2.1 Discharge the A/C system using an approved R-12 recovery/recycling machine. Follow the directions included in the machine's instruction manual.
2.2
With compressor replacement - Replace the compressor according to the appropriate repair manual. Install the adapter wire for the magnetic clutch, if necessary.
Without compressor replacement - Recharge the A/C system with R-12. Fill with the quantity of R-12 specified on the vehicles A/C label, or refer to S.I. 64 01 90 (3042). Do NOT add any oil when recharging with R-12.
2.3
With compressor replacement -
Without compressor replacement - Start the engine and turn on the A/C system. Run the vehicle with the A/C system turned on, engine at idle, for 10 minutes.
2.4
With compressor replacement -
Without compressor replacement - Repeat steps 2.1 through 2.3. This will remove most of the mineral oil from the R-12 system during the discharge. The remainder of the oil will be collected in the bottom of the receiver-dryer, which will be replaced. Any residual mineral oil left in the system will remain in the evaporator or condenser, and is not harmful to the retrofitted system.
2.5
With compressor replacement -
Without compressor replacement - Discharge the A/C system.
3. Converting the A/C System Components
3.1 Apply the new pressure switch onto the new receiver dryer, using a new 0-ring. All components are provided with the retrofit kit.
3.2 Replace the old receiver dryer with the new unit along with the pressure switch. Replace the 0-rings on all receiver dryer connections opened during the retrofit procedure, including pressure relief valve, if applicable (all necessary 0-rings are provided in the kit).
3.3 Install the service port quick-disconnect adapters.
The larger, red-capped adapter is for the high side line, which runs from the condenser to the expansion valve. The line with the sight glass is the high side line.
The smaller, blue-capped adapter is for the low side line, which runs from the evaporator to the compressor inlet.
Do not overtighten the adapters on the line fittings. The adapters contain 0-ring seals and will seat fully when properly torqued. The pipe fitting joints are relatively fragile and will shear if overtightened. A torque of 10 - 12 Nm should be applied.
3.4 (Only early E32 / E34 models with separate high, low and intermediate pressure switch assemblies)
Cut off connector X125 on the vehicle harness (1). Splice the wire ends together, solder the connection, and insulate it with shrink-wrap tubing (2).
3.5 Connect the plugs of the new pressure switch to the matching connectors on the vehicle harness (X126 and X127 resp. X1010).
3.6 Connect an R-134a vacuum pump to the vehicle and maintain a vacuum close to 30 inches for a minimum of 40 minutes. This extended vacuum purge will ensure that any remaining R-12 or moisture trapped in the system is boiled away before charging with R-134a. After the vacuum cycle completes, a vacuum decay test should be performed on the sealed system to detect any leaks caused by improperly seated 0-rings. Close off all manifold valves and monitor the pressure gauges for a loss of vacuum. Vacuum should not decrease over several minutes.
4. Charging A/C System with Lubricant and R-134a Refrigerant
4.1 Charge the system with compressor lubricant
With compressor replacement - No lubricant has to be charged into the system. The R-134a replacement compressor already contains the appropriate amount of PAG oil.
Without compressor replacement - Use the established system vacuum to draw the appropriate amount of PAG lubricant (P/N 82 11 1 468 042) into the NC system. Refer to the blue charging label included in the retrofit kit for the proper amount of PAG lubricant to use.
4.2 Charge the A/C system with R-134a. The refrigerant flow will push the PAG lubricant out of the service hoses and into the system. Charge with the appropriate amount of refrigerant according to the blue label included in the retrofit kit. Refer to the chart above if the kit contains multiple labels.
5. Checking A/C System for Leaks
Check for leaks with an electronic R-134a leak detector, especially at connections that were opened for the retrofit. Refer to S.I. 04 26 92 (3644) for an approved R-134a leak detector.
6. Verify that the A/C System works properly.
7. Locate and peel off the original engine-compartment A/C information label. Make certain this area is clean, and attach the new appropriate blue A/C information label from the retrofit kit. If necessary, refer to the chart above to determine the proper label. Both English and German language labels are provided in the kit. The English version of the label should be installed. Record the date and the name of the dealership/service organization that performed the retrofit on the label with a permanent marker.