Mechanically Driven A/C Compressor:

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2024 Audi SQ5, 2024 Audi Q5 e, 2024 Audi Q5, 2023 Audi SQ5, and 2023 Audi Q5 e. However, it is still accessible from the selected car via links, so may be relevant.

The A/C compressor is driven by a ribbed belt or an input shaft, which is driven by the vehicle engine.

Fig 1: Identifying A/C Compressor, Mechanically Driven

Courtesy of AUDI OF AMERICA, LLC

A/C Compressor with A/C clutch:

An electro-magnetic clutch -A- attached to the A/C compressor provides the power link between the belt pulley -B- and A/C compressor crankshaft when the A/C system is switched on.
An overload safeguard attached to the clutch plate or in the A/C compressor solenoid coil is tripped if the A/C compressor does not move freely, thus protecting the belt drive against overload.

A/C Compressor without A/C clutch:

An overload safeguard attached to the belt pulley -B- or installed in the A/C compressor drive unit is tripped if the A/C compressor does not move freely, thus protecting the belt drive against overload.

All A/C Compressors

The A/C compressor extracts the refrigerant gas from the evaporator, compresses it and sends it to the condenser.

NOTE:

The A/C compressor contains refrigerant oil, which can be mixed with refrigerant R134a under any temperature.

The type plate lists the type of refrigerant required for the A/C compressor. A regulator valve regulates pressure within the specified range (control characteristics) on the low pressure side.

A/C compressors with or without an A/C clutch are currently activated externally by a regulator valve -C-.

On A/C compressors without an A/C clutch, the engine is only to be started if the refrigerant circuit is completely assembled.

So that the A/C compressor does not get damaged when the refrigerant circuit is empty, the A/C clutch is turned off and the A/C Compressor Regulator Valve -N280- is no longer activated (A/C compressor runs at idle with engine).

If the refrigerant circuit is empty, an A/C compressor without A/C Clutch -N25- (with A/C Compressor Regulator Valve -N280-) is switched to internal lubrication by way of a valve.

Depending on the A/C compressor version, there may be a valve installed on the high pressure side of the A/C compressor, which prevents the liquid refrigerant from flowing back into the A/C compressor after the A/C system is turned off. If an A/C compressor with this valve is installed in a vehicle with a refrigerant circuit having an expansion valve, then it may take some time until the pressure in the high pressure side decreases (the expansion valve is cold and the pressure in the low pressure side quickly increases after it is turned off, the expansion valve closes and the refrigerant can flow slowly to the low pressure side). If the A/C compressor is switched on, the pressure on the low pressure side decreases, the expansion valve opens and the refrigerant can flow to the low pressure side.

On A/C compressors with an electro-magnetic clutch -A- and a regulator valve -C-, the electro-magnetic clutch -A- is, for the most part, only activated when the regulator valve -C- is activated. Refer to Refrigerant Circuit .