Volkswagen New Beetle. Manual - part 2000

 

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Volkswagen New Beetle. Manual - part 2000

 

 

PRESSURE RELIEF VALVE 

Fig. 13: Locating Pressure Relief Valve 
Courtesy of VOLKSWAGEN OF AMERICA, INC. 

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Function: Protects refrigerant circuit from overpressure. See Fig. 13 .  

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The pressure relief valve plug indicates if valve has opened to release pressure -arrow-. An adhesive plate 
is pushed out.  

A/C PRESSURE SWITCH - F129- 

A/C pressure switch -F129-, checking 

Visual check: Ensure that O-ring (color: red) 10.8mm x 1.8mm is seated in groove. 

Fig. 14: A/C Pressure Switch - F129- 
Courtesy of VOLKSWAGEN OF AMERICA, INC. 

Switch function between contacts -T4a/1- and -T4a/2- (at connector housing) switches A/C clutch -N25- off 
whenever: 

 

2003 Volkswagen New Beetle GLS 

1998-2004 HVAC Air Conditioning - New Beetle

  

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excessive refrigerant circuit pressure is present (e.g.: insufficient air flow over condensor or if system is 
overcharged)  

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insufficient refrigerant circuit pressure is present (e.g.: when refrigerant has leaked out). 

Switch function between contacts -T4a/3- and -T4a/4- (at connector housing) switches coolant fan -V7- to 
2nd speed when refrigerant pressure rises. 

Switching conditions 

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Contacts -1- and -2- open below 1.2 bar (17.4 psi) and closed above 2.4 bar (34.8 psi) switching threshold 

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Contacts -1- and -2- open above 32 bar (464 psi) and closed below 24 bar (348 psi) switching threshold  

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Contacts -3- and -4- closed above 16 bar (232 psi) and open below 12.5 bar (181.2 psi) switching 
threshold 

Fig. 15: A/C Pressure Switch - F129 
Courtesy of VOLKSWAGEN OF AMERICA, INC.

 

2003 Volkswagen New Beetle GLS 

1998-2004 HVAC Air Conditioning - New Beetle

  

Checking switch function 

Bridge contacts -1- and -2- with engine running. If A/C clutch -N25- switches on, refrigerant system may be 
empty, See A/C refrigerant system, testing with pressure gauges . 

Fig. 16: A/C Pressure Switch - F129 
Courtesy of VOLKSWAGEN OF AMERICA, INC. 

HIGH PRESSURE SENSOR -G65- 

Function 

Where equipped, the high pressure sensor -G65- -B-, transmits a square wave signal to Coolant Fan Control 
(FC) Module -J293- at a rate which varies according to the refrigerant system pressure. 

The signal from -G65- is processed as follows:

 

2003 Volkswagen New Beetle GLS 

1998-2004 HVAC Air Conditioning - New Beetle

  

Based on the pulse rate transmitted by -G65-, -J293- determines the A/C refrigerant system pressure and 
controls the function of the A/C clutch -N25- and coolant fan (s) accordingly. For example: 

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Switches the radiator fan -V7- to the next higher speed when pressure in the refrigerant circuit increases.  

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Switches off A/C clutch -N25- when pressure is excessive (for example when engine cooling is 
insufficient).  

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Switches off A/C clutch -N25- off when pressure is too low (for example with low/no refrigerant). 

The signal generated by high pressure sensor -G65- is also provided as an input to the Motronic Engine 
Control Module (ECM). As the amount of torque needed to drive the A/C compressor varies according to 
the refrigerant system pressure, the ECM processes this signal in order to enhance engine performance. 
Depending on the type of ECM, this signal may or may not appear as a duty cycle on the read measuring 
value block display (function 08). 

High pressure sensor -G65-, pin assignments 

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Contact 1: Ground (GND)  

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Contact 2: Square wave signal (output) to Coolant Fan Control (FC) Module -J293- and Motronic Engine 
Control Module (ECM) -J220-  

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Contact 3: Terminal 15 (ignition on)  

 

2003 Volkswagen New Beetle GLS 

1998-2004 HVAC Air Conditioning - New Beetle

  

 

 

 

 

 

 

 

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