Components

Components

Compressor







The compressor is driven via a poly V-belt by the vehicle engine.

Compressor with A/C clutch:
An electromagnetic coupling attached to the compressor provides the power link between pulley and compressor crankshaft when the air conditioning is switched on.

Compressor with no A/C clutch:
An overload safeguard attached to the pulley of the compressor is tripped if the compressor does not move freely, thus protecting the belt drive against overload.

The compressor draws in refrigerant gas from the evaporator, compresses it and conveys it to the condenser.

NOTE:
- The compressor contains refrigerant oil which mixes with refrigerant R134a at all temperatures.
- The rating plate indicates the refrigerant for which the compressor is designed. A valve regulates the pressure on the low-pressure side within the specified range (control characteristic).
- On compressors with no A/C clutch, a regulator valve is externally actuated.
- On compressors with no A/C clutch, the engine is only to be started following complete assembly of the refrigerant circuit.
- To prevent compressor damage if the refrigerant circuit is empty, the A/C clutch is deactivated and the A/C Compressor Regulator Valve N280 no longer actuated (compressor idles with engine).
- If the refrigerant circuit is empty, a compressor with no A/C Clutch N25 (with A/C Compressor Regulator Valve N280 ) is switched to internal lubrication by way of a valve.

Condenser







The condenser dissipates heat from the compressed refrigerant gas to the surrounding air.

In this process, the refrigerant gas condenses to form liquid.

Evaporator







The liquid refrigerant evaporates in the coiled pipes of the evaporator. The heat required for this is extracted from the air flowing past the evaporator fins. The air cools down. The refrigerant evaporates and is drawn in by the compressor together with the absorbed heat.

A defined quantity of refrigerant is supplied to the evaporator by way of a restrictor or expansion valve. In systems with an expansion valve the flow rate is regulated such that only gaseous refrigerant emerges at the evaporator outlet.

Reservoir







To ensure that the compressor draws in only gaseous refrigerant, the reservoir collects the mixture of vapor and gas coming from the evaporator. The vapor becomes gaseous refrigerant.

An oil extraction hole ensures that refrigerant oil entrained in the circuit does not remain in the reservoir.

Any moisture penetrating into the refrigerant circuit during assembly is trapped by a filter (desiccant bag) in the reservoir.

Gaseous refrigerant with oil is drawn in by the compressor.

NOTE:
- Replace reservoir if refrigerant circuit has been open for a lengthy period and moisture has penetrated or if replacement is stipulated on the basis of a specific complaint.
- Do not remove sealing plugs - A - and - B - until immediately prior to installation.
- If a reservoir is not sealed, the desiccant bag soon becomes saturated with moisture and can no longer be used.
- On installation, note arrow indicating direction of flow if applicable.

Restrictor







The restrictor forms a constriction. This constriction restricts the flow, thus separating the refrigerant circuit into high and low pressure sides. Upstream of the restrictor, the refrigerant is warm due to the high pressure. Downstream of the restrictor, the refrigerant is cold due to the low pressure. A strainer is provided upstream of the constriction to trap dirt. The strainer downstream of the constriction is designed to atomize the refrigerant before it enters the evaporator.

NOTE:
- Arrow - A - on restrictor faces evaporator.
- Always replace after opening circuit.
- Different versions, observe notes in various customer service information sources.

Receiver







The receiver collects the droplets of liquid and conveys them in a continuous stream to the expansion valve. Any moisture penetrating into the refrigerant circuit during assembly is collected by a dryer in the receiver.

NOTE:
- Replace receiver if refrigerant circuit has been open for a lengthy period and moisture has penetrated or if replacement is stipulated on the basis of a specific complaint.
- Only remove sealing plugs immediately prior to installation.
- If a receiver is not sealed, the desiccant bag soon becomes saturated with moisture and can no longer be used.
- On installation, note arrow indicating direction of flow if applicable.
- Depending on the construction of the refrigerant circuit, the receiver may also be secured on the condenser or installed in the condenser.
- Depending on the construction of the refrigerant circuit, the desiccant bag as the dryer cartridge may also be installed in the condenser.

Expansion Valve







The expansion valve atomizes the refrigerant flowing in and controls the flow rate in line with the quantity of heat transferred such that gas does not form until it reaches the evaporator outlet.

NOTE:
- Pay attention to correct part number when replacing expansion valve.
- Different characteristic curves matched to the appropriate circuit with Internally Regulated Compressor, with Externally Regulated Compressor.

O-Rings







These rings seal the joints between the individual components of the refrigerant circuit.

Only O-rings resistant to R134a refrigerant and the related refrigerant oils are to be used. This is guaranteed by genuine replacement parts.

O-rings:
- Always use only once.
- Make sure diameters - a - and - b - are correct.
- Moisten with refrigerant oil before installing

NOTE: The color coding of O-rings for R134a refrigerant circuits has been discontinued. Use is made of black and colored seals.

Refrigerant Circuit Pipes and Hoses
The mixture of refrigerant oil and refrigerant R134a corrodes certain metals (e.g. copper) and alloys and dissolves certain hose materials. Genuine replacement parts are therefore always to be used.

The pipes and hoses are linked by threaded joints or special connectors.

NOTE: Observe specified torques for threaded joints and use the specified release tools for connectors.

Pressure Relief Valve







The pressure relief valve is attached to the compressor or receiver.

The valve opens at a pressure of approx. 38 bar and closes again once the pressure has dropped (approx. 30 bar).

Not all the refrigerant escapes.

Certain versions feature a transparent plastic disc which breaks off as soon as the valve responds.