Audi A4 Owners & Service Manuals

Audi A4: Refrigerant Circuit Complaints

Possible Refrigerant Circuit Concerns

Test Requirements

  • Electrical Equipment, vacuum system and air duct fault-finding has not revealed any faults. Refer to Guided Fault Finding for the A/C system ("OBD" or "Guided Fault Finding for the A/C system"), → Wiring diagrams, Troubleshooting & Component locations.
  • The OBD/Guided Fault Finding for the A/C System with Vehicle Diagnostic Tester cannot detect a fault, the A/C compressor shut off condition is not displayed in the measured values block (only on vehicles with OBD "A/C System"). Refer to "Guided Fault Finding".

Possible Concerns

  Note

  • For all complaints marked.
  • If a malfunction occurs at only one evaporator in vehicles with two evaporators, also check the pressures in the refrigerant circuit.
  • Observe the test requirements. Refer to → Chapter "Test Requirements".

Vehicles without a High-Voltage System

  • Total cooling system failure *
  • Insufficient cooling output at all vehicles speeds or engine speeds *
  • None or insufficient cooling after driving a few miles *
  • No or insufficient cooling at one or both evaporators (for vehicles with two A/C units) *
  • The A/C compressor, A/C Clutch -N25- or A/C Compressor Regulator Valve -N280- are shut off by a pressure switch (for example, A/C Refrigerant Low Pressure Switch -F73-, Magnetic Clutch High Pressure Switch -F118-, A/C Pressure Switch -F129- or by the Front A/C Display Control Head -E87- or Climatronic Control Module -J255-) due to excessive or inadequate pressure *. Refer to → Heating, Ventilation and Air Conditioning; Rep. Gr.87; Refrigerant Circuit; System Overview - Refrigerant Circuit
  • None or sharp decrease in fresh-air supply after driving several miles (evaporator iced up) *

Vehicles with a high-voltage system

  • Total cooling system failure *
  • Insufficient cooling output at all vehicles speeds or A/C compressor speeds *
  • None or insufficient cooling after driving a few miles. *
  • No or insufficient cooling in the evaporator or on a heat exchanger (for example on the high-voltage battery heat exchanger) *. Refer to → Heating, Ventilation and Air Conditioning; Rep. Gr.87; Refrigerant Circuit; System Overview - Refrigerant Circuit.
  • No or insufficient heating output on the heat exchanger for the heat pump output (for example on the Audi Q7 e-tron) *. Refer to → Heating, Ventilation and Air Conditioning; Rep. Gr.87; Refrigerant Circuit; System Overview - Refrigerant Circuit.
  • The Electrical A/C Compressor -V470- is switched off by a control module (for example Front A/C Display Control Head -E87-, Climatronic Control Module -J255- or Thermal Management Control Module -J1024-) due to excessive or inadequate pressure. Use theVehicle Diagnostic Tester in the "Guided Fault Finding" function
  • None or sharp decrease in fresh-air supply after driving several miles (evaporator iced up).

All Vehicles

From these, the following complaints may also occur:

The A/C compressor makes noises

- Tighten compressor securing bolts and compressor bracket using a torque wrench.

- Check the routing of refrigerant lines; they must not touch other components and must not be subject to strain (align if necessary).

Noise (refrigerant hammer) occurring immediately after switching on air conditioner and/or when cornering or braking

- Discharge, evacuate and charge refrigerant circuit (too much refrigerant in circuit).

  Note

Too much refrigerant oil in the circuit could also cause this problem. This could occur if the amount of refrigerant oil was not adjusted when replacing the A/C compressor.

Water sprays out of vents (in dash panel or footwell) although air conditioning system is otherwise functioning properly:

- Check proper routing of condensate drain; it must not be crushed or kinked.

- Check condensation drain valve, it must not be clogged by wax or underbody sealant and must close properly.

- Check plenum chamber cover; it must not be damaged and must be properly installed (to stop water running into evaporator).

- Check the water drains in plenum chamber; they must not be blocked (for example, by leaves).

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