Low Pressure Sensor / Switch: Testing and Inspection

Switch -F129-:

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

Switch part between contacts -T4a/1 - and -T4a/2 of connector housing switches magnetic coupling -N25- off when refrigerant system insufficiently filled or pressure too high.
- Opens below 1.2 bar (17.4 psi) and closes again above 2.4 bar (35.8 psi) (switching threshold)
- Opens above 32 bar (464 psi) and closes again below 24 bar (34.8 psi) (switching threshold)
- Briefly bridge circuit between chambers 1 and 2 with engine running. If the compressor clutch -N25- switches on, the refrigerant system is empty. Take vehicle to specialist service workshop.

Switch part between contacts 3 and 4 of connector housing
- Closes above 16 bar (232 psi) and opens below 12.5 bar (181.3 psi) (switching threshold)