A/C Compressor Regulator Valve N280

WARNING: This page does not describe the selected car, but rather 17 other vehicles, including the 2009 Audi S4, 2009 Audi A4, 2008 Audi S4, 2008 Audi RS 4, and 2008 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: A/C Compressor Regulator Valve N280

Courtesy of VOLKSWAGEN UNITED STATES, INC.

The regulator valve is installed in the compressor. It is actuated by the A/C Control Head E87 or the Climatronic Control Module J255. The pressure on the low pressure side is influenced by way of the regulator valve, thus regulating the temperature in the evaporator.

NOTE:

The A/C Compressor Regulator Valve N280 is part of the compressor and cannot be replaced separately.

Fig 2: Identifying A/C Compressor Speed Sensor G111

Courtesy of VOLKSWAGEN UNITED STATES, INC.

A/C Compressor Speed Sensor G111

Inductive sensor

The sensor pulses (4 per compressor revolution) and the engine speed enable the A/C Control Head E87 or the Climatronic Control Module J255 to calculate belt slip.

If the belt slip exceeds a specified value, the compressor is switched off by the control module via the A/C clutch.

NOTE:

The sensor is installed in Audi vehicles with compressor drive via poly V-belt and Zexel compressor.

Fig 3: Refrigerant Temperature Sensor G454

Courtesy of VOLKSWAGEN UNITED STATES, INC.

Refrigerant Temperature Sensor G454

The Refrigerant Temperature Sensor (with temperature-dependent resistor) is installed e.g. in high pressure line in vicinity of the compressor.

In the refrigerant circuit, there is a direct relationship between temperature and pressure, if there should be too little refrigerant in the refrigerant circuit, the temperature in the refrigerant circuit rises higher than intended for this pressure while A/C system is running.

NOTE:

Installed e.g. in the Audi Q7 with specific engines → 87 - Air conditioning and → Electrical Wiring Diagrams, Troubleshooting and Component Locations
The A/C control head, Climatronic Control Module J255 evaluates pressure and temperature in the refrigerant circuit and switches off the compressor in the event the temperature increases above the value stored for this pressure → 87 - Air conditioning and in the Guided Fault Finding function of A/C system

Coolant Fan Control Module J293

(Not on refrigerant circuit)

Fig 4: Coolant FC (Fan Control) Control Module - J293

Courtesy of VOLKSWAGEN UNITED STATES, INC.

This control module switches the A/C clutch and thus the compressor on and off. It switches the coolant fans and calculates the pressure in the refrigerant circuit on vehicles with High Pressure Sensor G65 → Electrical Wiring Diagrams, Troubleshooting and Component Locations and → 87 - Air conditioning .