Refrigerant Circuit, Servicing

Refrigerant Circuit, Servicing

Before working on electrical system (wiring), remove relevant fuse(s).

• Disconnect battery before starting electric welding work on vehicle.

The A/C refrigerant system may be drained and opened only if it is for safety reasons. Refer to=> [ A/C and Refrigerant Safety Precautions ] A/C and Refrigerant Safety Precautions or if components of the A/C refrigerant system must be replaced. Refer to=> [ Refrigerant Circuit, Draining ] Refrigerant Circuit, Draining.

When performing all other usual vehicle repair work, the refrigerant circuit of the A/C system should remain closed.

Servicing operations that can be performed on the heating and air conditioning system without opening the refrigerant circuit are described in this Repair Manual. Refer to=> [ A/C System Control and Regulation Components Outside Passenger Compartment ] A/C System Control and Regulation Components Outside Passenger Compartment.

• The connections for the senders/switches described in this Workshop Manual are fitted with a valve which closes automatically when the switches are unscrewed. These switches can thus be replaced in any Audi and Volkswagen workshop even though the refrigerant circuit is fully charged.

Service work on the A/C system that require the refrigerant circuit to be discharged and thus cannot be performed in every Audi and VW workshop are described in => [ Refrigerant Circuit Components Overview ] Refrigerant Circuit Components Overview. Certain tools are required to discharge the refrigerant circuit, these work procedures must only be performed by trained personnel as well. Therefore, bring vehicle to a workshop that has the necessary tools and in which the work can be performed accordingly by qualified personnel if necessary.

• Refrigerant in refrigerant circuit is never to be topped up (drain, evacuate and refill circuit).

• Compressor is always driven when engine is running; there is no magnetic clutch. Engine is not to be started unless refrigerant circuit has been properly assembled. For example; if the refrigerant lines 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. Such internal heat generation results from the fact that, even with delivery near 0%, the compressor is confronted with a fixed resistance (sealed circuit).

• To stop the A/C compressor from destroyed when the refrigerant circuit is empty, it is designed such that delivery is reduced to roughly 0% and lubrication is maintained by way of an internal oil circuit with the oil left in the A/C compressor.

• The entire amount of refrigerant oil to be added to the refrigerant circuit is in the replacement compressor.

• Different refrigerant oils are required for compressors made by Denso, Sanden and Zexel.

• Beginning the production year 2006, the name of the "Zexel" A/C compressor was changed from "Zexel" to "Valeo".

• Coat the O-ring seals lightly with refrigerant oil prior to installation. Refer to=> [ Refrigerant Circuit O-rings ] Refrigerant Circuit O-rings.

• The specified diameters for O-rings and the tightening torque pertain also to the threaded connections of the refrigerant lines or refrigerant hoses between the separate components.

• Only install O-rings that have been approved to be used with refrigerant R134a. Refer to => [ Refrigerant Circuit O-rings ] Refrigerant Circuit O-rings.

• Check cooling performance; refer to => [ A/C Unit, Checking Cooling Output ] A/C Unit, Checking Cooling Output.

• Check pressures in refrigerant circuit.

• Appropriate current flow diagrams can be found in Current Flow Diagrams, Electrical Fault Finding and Fitting Locations binder.

• A data plate in engine compartment indicates the refrigerant used and capacity.

• Contact corrosion. Refer to => [ Contact Corrosion ] Contact Corrosion.

• Notes for performing Guided Fault Finding on the A/C system, refer to => [ Performing Guided Fault Finding ] Performing Guided Fault Finding

• Checking the electrical components on the A/C system, refer to => [ Checking Electrical Components ] Checking Electrical Components

• Components Actuated by A/C System, Electrical Test. Refer to => [ Components Actuated by A/C System, Electrical Test ] Components Actuated by A/C System, Electrical Test.

• Refrigerant circuit, servicing, refer to=> [ Refrigerant Circuit, Servicing ] Service and Repair.