| The air conditioner compressor is driven by the engine via a poly V-belt or a drive shaft. |
| Air conditioner compressor with magnetic clutch: |
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| An electromagnetic clutch -A- attached to the air conditioner compressor provides the power link between the pulley -B- and the compressor crankshaft when the air conditioning system is switched on. |
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| An overload safeguard attached to the clutch plate or fitted in the solenoid of the air conditioner compressor is triggered if the air conditioner compressor is not running smoothly in order to protect the belt drive against overload. |
| Air conditioner compressor with no magnetic clutch: |
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| An overload safeguard attached to the pulley -B- or fitted in the drive unit of the air conditioner compressor is triggered if the air conditioner compressor is not running smoothly in order to protect the belt drive against overload. |
| All air conditioner compressors |
| The air conditioner compressor draws in refrigerant gas from the evaporator, compresses it and conveys it to the condenser. |
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| The air conditioner compressor contains refrigerant oil which mixes with refrigerant R134a at all temperatures. |
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| The rating plate indicates the refrigerant for which the air conditioner compressor is designed. A valve regulates the pressure on the low-pressure end within the specified range (control characteristic). |
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| At present, actuation is effected externally by way of a regulating valve -C- on air conditioner compressors with or without magnetic clutch. |
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| On air conditioner compressors with no magnetic clutch, the engine is only to be started following complete assembly of the refrigerant circuit. |
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| To prevent air conditioner compressor damage if the refrigerant circuit is empty, the magnetic clutch is deactivated and the air conditioner compressor regulating valve -N280- no longer actuated (air conditioner compressor idles with engine). |
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| If the refrigerant circuit is empty, an air conditioner compressor with no air conditioning system magnetic clutch -N25- (with air conditioner compressor regulating valve -N280-) is switched to internal lubrication by way of a valve. |
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| Depending on the version of the air conditioner compressor, the high-pressure end of the air conditioner compressor may be fitted with a valve to prevent the backflow of liquid refrigerant into the compressor after switching off the air conditioning system. If an air conditioner compressor with this valve is fitted on a vehicle with a refrigerant circuit with an expansion valve, a relatively long period may elapse before the pressure on the high-pressure end decreases (the expansion valve is cold and the pressure on the low-pressure end increases rapidly after switch-off, the expansion valve closes and the refrigerant can only flow slowly to the low-pressure end). If the air conditioner compressor is switched on, the pressure on the low-pressure end decreases, the expansion valve opens and the refrigerant can flow to the low-pressure end. |
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| In the case of air conditioner compressors with an electromagnetic clutch -A- and a regulating valve -C-, the electromagnetic clutch -A- is usually only actuated when the regulating valve -C- is actuated as well → Air conditioning; Rep. gr.87. |
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