Volkswagen New Beetle. Manual - part 1999

Fig. 10: Identifying A/C Pressure Switch -F129- 
Courtesy of VOLKSWAGEN OF AMERICA, INC. 

Switch -F129- has three functions:  

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Switches the A/C clutch -N25- off when excessive refrigerant circuit pressure is present (e.g.: insufficient 
air flow over condensor or when overcharged).  

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Switches the A/C clutch -N25- off when insufficient refrigerant circuit pressure is present (e.g.: when 
refrigerant has leaked out).  

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Switches on the second speed coolant fan -V7- when refrigerant circuit pressure increases.  

High pressure sensor -G65- 

Fig. 11: Identifying High Pressure Sensor -G65-

NOTE:

Depending on engine type, refrigerant systems have either an A/C pressure 
switch -F129- or high pressure sensor -G65- instralled. Refer to system wiring 
diagrams.

 

2003 Volkswagen New Beetle GLS 

1998-2004 HVAC Air Conditioning - New Beetle

  

Courtesy of VOLKSWAGEN OF AMERICA, INC.

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 is processed as follows: 

Based on the signal transmitted by -G65-, -J293- determines the A/C refrigerant system pressure and controls 
A/C clutch -N25- and coolant fan functions accordingly. For example:  

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

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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 -G65- signal is also input to the Motronic Engine Control Module (ECM). As the amount of torque 
needed to drive the A/C compressor varies according to 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). 

For -G65- signal, checking, see High pressure sensor -G65- . 

A/C system hoses and lines 

The mixture of refrigerant oil (PAG oil) and refrigerant R-134a attacks some metals and alloys (for example, 
copper) and breaks down certain hose material. Use only hoses and lines that are identified with a green mark 
(stripe) or the lettering "R-134a". 

Hoses and lines are fastened together with threaded couplings/fittings and are retained (to bodywork or 
components) with specially isolated hose clamps. 

A/C REFRIGERANT SYSTEM, REPLACING COMPONENTS 

Replacement A/C compressors, evaporators and condensers supplied by the Parts Dept. are filled with Nitrogen. 
If gas (Nitrogen) does not escape when component is first opened, the component may be faulty (leaking), do 
not install. 

Replacement A/C compressors are filled with the total refrigerant oil quantity needed for the entire refrigerant 
system. 

Always replace the receiver drier whenever the refrigerant system has been left open. Install immediately after 
opening to prevent moisture contamination of drier desiccant. Moreover, keep refrigerant system and other 

NOTE:

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During servicing, all couplings, fittings and related fasteners must be 
torqued to specifications. See A/C refrigerant system, replacing 
components .  

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Ensure that only special tools (as specified) are used while servicing.  

 

2003 Volkswagen New Beetle GLS 

1998-2004 HVAC Air Conditioning - New Beetle

  

replacement components sealed for as long as possible to minimize the chance of dirt and moisture 
contamination. 

Always plug open refrigerant line connections to prevent dirt and moisture contamination. 

If the system has been discharged due to a damaged or leaking component (refrigerant hose/line, compressor, 
evaporator, condenser, etc.), flush the refrigerant system first with compressed air, then with nitrogen (available 
locally) and collect the oil that runs out. This will remove the refrigerant oil which may be saturated with 
moisture. 

If the compressor is replaced, do not add any additional oil as the total amount of oil required is already in the 
compressor. 

Dispose of contaminated refrigerant oil following laws governing hazardous waste disposal. Do not combine 
any refrigerant oil with any other old oils such as engine oil or transmission fluid. 

Follow all applicable Warnings and Cautions when working on the A/C system. 

A/C REFRIGERANT SYSTEM, SERVICING 

CAUTION: DO NOT flush R-134a refrigerant system with R-11. R-11 is not compatible 

with refrigerant R-134a and PAG oil and will cause total system 
contamination. If the compressor is not replaced after flushing the system, 
fill compressor with the correct type and quantity of refrigerant oil as 
specified under A/C system capacities, See A/C refrigerant system, 
capacities . Fill compressor with the total system oil capacity.

NOTE:

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Before carrying out any work on the A/C refrigerant system, refer to A/C 
refrigerant system safety measures, See A/C refrigerant system .  

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Except where indicated with *, all system components illustrated must 
only be serviced or replaced after discharging refrigerant system.  

 

2003 Volkswagen New Beetle GLS 

1998-2004 HVAC Air Conditioning - New Beetle

  

Fig. 12: A/C Refrigerant System Components (Engine Compartment)
Courtesy of VOLKSWAGEN OF AMERICA, INC. 

1. Damper  

2. Refrigerant hose  

3. Refrigerant pipe  

4. Refrigerant pipe 

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From receiver drier to expansion valve  

5. High pressure service valve 

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Only use Kent Moore ACR4 or equivalent  

6. A/C pressure switch -F129- (4-Pin) or high pressure sensor -G65- (3-Pin) * 

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Depending on engine type, refrigerant systems have either an A/C pressure switch -F129- or high 
pressure sensor -G65- instralled. Refer to system wiring diagrams.  

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Checking -F129-, See A/C pressure switch -F129-, checking  

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Checking -G65-, See High pressure sensor -G65-  

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Removing and installing, See Removing And Installing A/C Pressure Switch -F129- And High 
Pressure Sensor -G65-  

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Component can be removed without discharging refrigerant system  

7. Expansion valve  

8. Evaporator 

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In heater/evaporator unit  

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Removing, See Heater/evaporator unit, disassembly and assembly  

9. Refrigerant hose  

10. Refrigerant hose 

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From compressor to condenser  

11. Condenser 

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Removing and installing, See Condenser, removing and installing  

12. Pressure relief valve 

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On compressor  

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Checking, See Fig. 13  

13. Compressor 

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Sanden SD7-V16  

14. A/C clutch -N25-* 

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Clutch assembly can be serviced without discharging refrigerant system.  

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Servicing, See A/C clutch -N25-, servicing (Sanden) .  

15. Receiver drier  

NOTE:

The following list refers to items in Fig. 12 .

 

2003 Volkswagen New Beetle GLS 

1998-2004 HVAC Air Conditioning - New Beetle