Switches and Sensors on Refrigerant Circuit and Connections

A/C Refrigerant High Pressure Switch -F23-

Note

For switching pressures, removing and installing switches and switch arrangement and version, see vehicle-specific refrigerant circuit.

Function:

Switches the coolant fan to the next higher level when the pressure in the refrigerant circuit increases (approximately 16 bar (232 psi) ).

Magnetic Clutch High Pressure Switch -F118-

Note

For switching pressures, removing and installing switches and switch arrangement and version, see vehicle-specific refrigerant circuit.

Function:

Switches off A/C compressor when there is excessive pressure in the refrigerant circuit (approximately 32 bar (464 psi) ).

A/C Refrigerant Low Pressure Switch -F73-

Note

For switching pressures, removing and installing switches and switch arrangement and version, see vehicle-specific refrigerant circuit.

Function:

Switches off A/C compressor when there is excessive pressure in the refrigerant circuit (approximately 2 bar (29 psi) ).

Refrigerant Circuit Connections with Valve for Switches

Note

For switching pressures, removing and installing switches and switch arrangement and version, see vehicle-specific refrigerant circuit.

WARNING

There is a danger of ice-up.

Refrigerant will leak out if refrigerant circuit is not discharged.

Refrigerant must be extracted before removing valve -C-. If refrigerant circuit is not opened within 10 minutes of extraction, pressure may form in refrigerant circuit due to evaporation. Extract the refrigerant once more.

• Different threads for switch on high pressure and low pressure sides.
• Only valves and o-rings that are resistant to refrigerant R134a and refrigerant oil must be installed.

1. 1
   Connection (soldered in)
2. 2
   O-Ring
3. 3
   Valve (with o-ring)

   

A/C Pressure Switch -F129-

Note

For switching pressures, removing and installing switches and switch arrangement and version, see vehicle-specific refrigerant circuit.

This pressure switch has 3 functions:

1. Switches the coolant fan to the next higher level when the pressure in the refrigerant circuit increases (approximately 16 bar (232 psi) ).

2. Switches off A/C system if pressure is excessive (approximately 32 bar (464 psi) ), for example. because of insufficient engine cooling.

3. Switches off A/C system if pressure is insufficient (approximately 2 bar (29 psi) ), for example. loss of refrigerant.

Note

A/C Pressure Switch -F129- replaces the A/C Refrigerant High Pressure Switch -F23-, A/C Refrigerant Low Pressure Switch -F73- and the Magnetic Clutch High Pressure Switch -F118-.

High Pressure Sensor -G65-

Note

For switching pressures, removing and installing switches and switch arrangement and version, see vehicle-specific refrigerant circuit.

This High Pressure Sensor -G65- is installed in place of an A/C Pressure Switch -F129-.

The high-pressure sensor generates a square-wave signal or a data telegram when voltage is applied. This signal changes along with pressure in the system.

The downstream control modules (coolant fan control module, ECM), Front A/C Display Control Head -E87- or Climatronic Control Module -J255-, etc.) use this signal to calculate pressure in the refrigerant circuit and to activate the coolant fans and motor and A/C Clutch -N25- or to change the A/C Compressor Regulator Valve -N280- activation.

A/C Pressure/Temperature Sensor -G395-

Note

For switching pressures, removing and installing switches and switch arrangement and version, see vehicle-specific refrigerant circuit.

WARNING

There is a danger of ice-up.

Refrigerant will leak out if refrigerant circuit is not discharged.

The refrigerant must be extracted before the A/C Pressure/Temperature Sensor -G395- is removed. If refrigerant circuit is not opened within 10 minutes of extraction, pressure may form in refrigerant circuit due to evaporation. Extract the refrigerant once more.

This A/C Pressure/Temperature Sensor -G395- is installed instead of the High Pressure Sensor -G65- or A/C Pressure Switch -F129-.

The pressure signal is always being checked, where the temperature signal is only checked at temperatures above 0 ºC (32 ºF).

The Climatronic Control Module -J255- operates with this information and controls the coolant fans and activation of the A/C Compressor Regulator Valve -N280-.

A/C Compressor Regulator Valve -N280-

Note

For switching pressures, removing and installing switches and switch arrangement and version, see vehicle-specific refrigerant circuit.

The regulator valve is implemented into the compressor. It is activated by the A/C Display Control Head -E87- or Climatronic Control Module -J255-. Pressure on the low pressure side is influenced via the regulator valve and thus regulates the temperature in the evaporator.

Note

The A/C Compressor Regulator Valve -N280- is a component of the A/C compressor and cannot be replaced separately.