A/C System, General Repair Guidelines

A/C System, General Repair Guidelines

DANGER!
Remove the respective fuse(s) before working on electrical wires

• Disconnect battery before starting electric welding work on vehicle.

Refrigerant circuit of A/C system must not be discharged and opened => [ Refrigerant Circuit, Discharging with Service Station ] Refrigerant Circuit, Discharging with Service Station unless it is necessary because of safety precautions => [ Climate Control System and Refrigerant ] Climate Control System and Refrigerant or unless components of the refrigerant circuit of the A/C system have to be to replaced.

When performing all other usual vehicle repair work, the refrigerant circuit of the A/C system should also 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 Information

• The connections for the sensors/switches mentioned in this Repair Information are not always equipped with a valve. Valve closes automatically when unscrewing the switch, therefore only switches on which the connection is equipped with a valve maybe replaced when the refrigerant circuit is charged.

Servicing operations on A/C system for which it is necessary to discharge the refrigerant circuit and thus cannot be performed in every workshop are also in this Repair Information described => [ A/C Refrigerant System, Servicing Notes ] A/C Refrigerant System, Servicing Notes (vehicle must be delivered to an A/C system service point workshop to discharge the refrigerant circuit).

• Note for vehicles with parking/auxiliary heater (with poor heating performance)

• If customer complains of poor heating performance, check heating output of A/C system and function of Coolant Pump (V50) (also Coolant Pump (V36) on vehicles with 6 cyl. FSI engine) => [ Heating Performance of HVAC System and Function of Coolant Pump, Checking ] .

• If poor or insufficient heating performance (e.g. at low engine speeds) is reported on vehicles with a parking/auxiliary heater installed as optional equipment, check activation of Coolant Pump (V50) (also Coolant Pump (V36) on vehicles with 6 cyl. FSI engine), Engine Coolant (EC) Switch-Off Valve (heater) (N279), incorporation of parking/auxiliary heater into coolant circuit and function of parking/auxiliary heater (activation of Auxiliary Heater Control Module (J364)).

• By activation of Coolant Pump (V50) (also Coolant Pump (V36) on vehicles with 6 cyl. FSI engine), coolant flow through A/C system heater core(s) is increased at low engine speeds, achieving better heating performance.

• Coolant Pump (V50) (or Coolant Pump (V36)) is switched on by front Climatronic Control Module (J255) as soon as all switch-on conditions are met (ignition is switched on, front Climatronic Control Module (J255) is switched on, OFF button not operated, etc.) => [ Heating Performance of HVAC System and Function of Coolant Pump, Checking ] .

• Front Climatronic Control Module (J255) also switches the Coolant Pump (V50) (also Coolant Pump (V36) on vehicles with 6 cyl. FSI engine) if it receives information via Comfort CAN-Bus system from the Auxiliary Heater Control Module (J364).

• Incorporation of parking/auxiliary heater (and of Coolant Pump (V50) and of Coolant Pump (V36)) into coolant circuit.