Refrigerant Pressure Sensor / Switch: Testing and Inspection

Testing, removal and installation of pressure switch for A/C compressor in fluid reservoir





Testing

- Switch on ignition and air-conditioner
- With voltmeter check positive connection to battery and ground one after the other at the two terminals on the pressure switch (S31/1). If ground is present only at one terminal, the air-conditioner is either not charged sufficiently or the pressure switch (S31/1) is defective. If ground is present at both terminals and the refrigerant compressor does not switch on check compressor shut-off.
- Check refrigerant level, for this purpose allow engine to run at idle and jump the two terminals on the pressure switch (S31/1). Assure that refrigerant flows without bubbles after A/C compressor switches on by watching obervation glass on fluid reservoir; recharge air-conditioner if required.


Removal and installation

- Drain air-conditioner.
- Disconnect both plugs on pressure switch (S31/1).
- Unscrew pressure switch (S31/1).
- Plug connection on fluid reservoir.
- Reinstall in reverse order; moisten O-ring with refrigeration oil and tighten to 20 f 4 Nm.
- Charge air conditioner, check for proper function and leakage, allow engine to run at idle speed only for first 4 minutes.


Data
Pressure switch (S31/1) in fluid reservoir for A/C compressor
switch-off pressure: 2.0/30 bars
switch-on pressure: 2.6/22 bars