Basic Rules For Working on Refrigerant Circuit

Basic Rules For Working On Refrigerant Circuit

General
- Follow workplace-specific instructions.
- Ensure absolute cleanliness when working.
- Wear safety goggles and gloves when working with refrigerant and nitrogen.
- Workshop extraction systems are to be switched on.
- Use A/C service station to discharge refrigerant circuit, then unfasten screw connections and replace malfunctioning components.
- Use caps to seal off opened assemblies and hoses to prevent ingress of moisture and dirt.
- Make exclusive use of tools and materials intended for refrigerant R134a.
- Re-seal opened refrigerant oil vessels to guard against moisture.

NOTE:
- After completing service work, screw sealing caps (with seals) onto all connections with valves as well as service connections.
- Before starting up air conditioning system, pay attention to vehicle-specific capacities Refrigerant R134a/Refrigerant Oil Capacities and Specifications.
- Do not top up refrigerant. Extract existing refrigerant and recharge system.

Refrigerant Circuit, Cleaning
Flush refrigerant circuit with refrigerant R 134a (or with compressed air and nitrogen) if:
- Moisture or dirt has entered into refrigerant circuit (e.g. following an accident)
- Refrigerant oil is dark and viscous.
- There is too much refrigerant oil in the refrigerant circuit after compressor replacement.
- The A/C compressor had to be replaced on account of "internal" damage (e.g. noise or no output).

NOTE: When flushing components with compressed air and nitrogen, always extract the gas mixture escaping from the components using suitable extraction units (workshop extraction system).

Additional Notes for Vehicles with A/C Compressor Regulator Valve N280)
- The engine is only to be started following complete assembly of the refrigerant circuit (constant compressor operation).
- If engine has to be operated with the refrigerant circuit empty, only do so for as long as absolutely essential and avoid high engine speeds.

O-Rings
- Use only seals which are resistant to refrigerant R134a and the related refrigerant oils. Color coding of O-rings is no longer employed. Black and colored O-rings are used.
- Pay attention to correct ID of seals used.
- Seals are only to be used once.
- Before installing, moisten seals slightly with refrigerant oil (PAG oil).

Before starting up Air Conditioning System after Charging
- Rotate compressor roughly 10 times by hand using the clutch plate or pulley of the A/C clutch.
- Start engine with air conditioning system switched off ( A/C Clutch N25 and A/C Compressor Regulator Valve N280 are not actuated).
- Following engine idling speed stabilization, switch on compressor and run it for at least 10 minutes at idling speed with maximum cooling output.