Refrigerant Pressure Sensor / Switch: Description and Operation

2003 Volkswagen Eurovan V6-2.8L (AXK)SECTION Description and Operation



A/C Refrigerant System Component Functions, Overview

A/C Pressure Switch -F129-








Switch has three functions:

- Switches the A/C clutch -N25- off when excessive refrigerant circuit pressure is present (e.g.: insufficient air flow over condenser or when overcharged).
- Switches the A/C clutch -N25- off when insufficient refrigerant circuit pressure is present (e.g.: when refrigerant has leaked out)
- Switches on the second speed coolant fan -V7- when refrigerant circuit pressure increases.

Function






Pressure switch component between blue wires switches A/C clutch -N25- off when too little or excess refrigerant system pressure is present.

- Switch opens (compressor off) below 2 bar (29.4 psi) and closes (compressor on) above 3 bar (43.5 psi).
- Switch opens (compressor off) above 32 bar (464 psi) and closes (compressor on) below 24 bar (348 psi).
- Switch closes (fan on) above 16 bar (232 psi) and opens again (fan off) below 12.5 bar (181.25 psi).
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.