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Skoda Workshop Service and Repair Manuals

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Properties of refrigerant R 134a and of the refrigerant oil > < Extractor, filler and measurement valves for quick couplings of the service position on the refrigerant circuit

Octavia Mk2

Parts for securing the refrigerant circuit
Parts for securing the refrigerant circuit
   
Pressure relief valve
The pressure relief valve is located on the compressor and opens in the event of overpressure. The refrigerant does not flow out completely.
If the valve was opened the adjoining area is also covered in oil.
Opening pressure: 4 ±0.4 MPa (40±4 bar)
Closing pressure: at least 3.1 MPa (31 bar)
  Note
If the pressure relief valve was opened, determine the cause of the overpressure in the system and eliminate it.
  S87-0143
Belt protection for blocked compressor
The compressor operates continuously via a driver clutch -2- and -3- in the belt drive, whether or not the air conditioning system is switched on.
If the compressor blocks, the rubber elements -3- will shear off or the driver disc -2- will become deformed depending on the compressor temperature (it depends on the temperature).
In any case the belt pulley of the compressor can rotate while the driver disc/compressor shaft is at a standstill.
Replace the compressor.
Various compressors with a differently designed anti-lock device are fitted engine dependent ( → Chapter).
  Note
t  This anti-lock device applies for the Denso compressor.
t  The anit-lock device for the compressors Zexel and Sanden is designed differently.
  S87-0230
High-pressure sender -G65-
The high-pressure sender -G65- determines the pressure in the refrigerant circuit and transmits the values to the Air conditioning system control unit -J301- (climatic) or to the Climatronic control unit -J255-.
The following are shifted via these control units:
t  The radiator fan -V7- switches to the next speed in the event of a pressure rise in the refrigerant circuit
t  Reduction of the compressor output if the pressure is too high, 3.2 MPa (32 bar), e.g. too little engine cooling
t  Reduction of the compressor output if the pressure is too low, 0.2 MPa (2 bar), e.g. refrigerant loss
  S87-0233
Air conditioning system control unit -J301- (Climatic)
The air conditioning system control unit -J301 - is integrated in the heating and air conditioning system control.
It processes information such as ambient temperature, actual and required interior temperature, evaporator temperature, pressure in the refrigerant circuit, engine load and driving conditions.
Depending on the required cooling output the climatronic control unit -J301 - sends a PWM signal (pulse width modulated) to the regulating valve of the compressor.
  Note
t  On vehicles fitted with Climatronic, the Climatronic control unit -J255- takes over these functions.
t  As of MY 09, different arrangement of actuating elements and displays.
  S87-0221
Regulating valve for compressor of air conditioning system -N280-
Depending on the required cooling output the regulating valve -arrow- (component of the compressor, cannot be replaced separately) receives a PWM signal from the air conditioning system control unit - J301- or Climatronic control unit -J255- and regulates the displacement of the compressor via the suction pressure (position of the articulated disc).
This guarantees that the output of the compressor does not exceed the requirements.
  Note
Depending on the type of manufacturer, the regulating valve can be constructively designed differently.
  S87-0231

Properties of refrigerant R 134a and of the refrigerant oil > < Extractor, filler and measurement valves for quick couplings of the service position on the refrigerant circuit