Refrigerant Circuit, General Precautions

Refrigerant Circuit, General Precautions

- Workplace-specific instructions. Refrigerant from A/C Systems/Refrigerant Oils should be hung in the workplace and followed.
- Ensure absolute cleanliness when working.
- Wear work clothing, safety goggles and gloves when working with refrigerant and nitrogen.
- Switch on existing ventilation systems.
- Use service station to discharge refrigerant circuit, only then open 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.

- Flushing refrigerant circuit with compressed air and nitrogen.
- Flushing refrigerant circuit with R134a refrigerant.

On vehicles with A/C compressor without magnetic clutch:

NOTE:
- The engine should only be started after assembling the refrigerant circuit.
- If possible start engine only with a filled refrigerant circuit.
- A/C compressor is driven permanently by the ribbed belt pulley/torsion elastic clutch (not fitted with a magnetic clutch):
- If an A/C compressor locks-up the overload protection for the A/C compressor shaft is triggered. If no bumps are visible on the ribbed belt pulley/overload protection, the A/C compressor may be blocked. Another indicator is abraded rubber material in the area of the ribbed belt pulley/overload protection
- The A/C compressor is equipped with a protected oil supply, this prevents A/C compressor damage in the event that the system is empty. This means that approximately 40 to 50 cu.cm of refrigerant oil remains in the A/C compressor.
- The engine may only be started when the refrigerant circuit is installed correctly. For example; if the refrigerant pipes are not connected to A/C compressor, when the engine is running the A/C compressor may heat up (via internal heat generation) so much that the A/C compressor will be damaged.
- A/C Compressor Regulator Valve N280 is not activated when the refrigerant circuit is empty and the A/C compressor idles with the engine.

- If it is necessary to start the engine with a discharged refrigerant circuit:
- Refrigerant circuit must be fully assembled.
- At least 1/4 of the prescribed refrigerant oil must be in the A/C compressor.
- No not rev engine higher than 2000 rpm.
- The engine should run 10 minutes.

O-ring Seals
- Make exclusive use of seals which are resistant to refrigerant R134a and the related refrigerant oils. Color coding of Orings is no longer employed. Colored and black O-rings are used.
- Ensure inner diameter on seals used is correct.
- Use O-rings only once.
- Before installing O-rings, coat lightly with refrigerant oil (PAG oil).

NOTE:
- When flushing components with compressed air and nitrogen, always extract the gas mixture escaping from the components with suitable extraction units (workshop extraction system).
- After engine all service work, screw sealing caps (with seals) onto all connections with valve and service connections.

Before starting up A/C system. Observe vehicle specific filling capacities Heating, Ventilation and Air Conditioning.

Do not top off refrigerant, extract refrigerant present and fill the system anew

After Charging A/C System
- After installing a new A/C compressor or fresh refrigerant oil has been filled into compressor (e.g. after blowing through the A/C system), turn ribbed belt pulley of A/C compressor 10 rotations by hand before starting the engine. This prevents damage to the A/C compressor.
- For 5-cyl. and 10 cyl. diesel engines, rotate A/C compressor 10 rotations by hand at overload protection. Then install A/C compressor. This prevents damage to the A/C compressor.
- Start engine with A/C system switched off ( A/C Clutch N25 and A/C Compressor Regulator Valve N280 are not actuated).
- Following engine idling speed stabilization, switch on A/C compressor and run it for at least 10 minutes at idling speed with maximum cooling output.