Cooling Output Of Front A/C System Is Not Achieved

Cooling Output Of Front A/C System Is Not Achieved






Test Continuation The A/C compressor actuation is switched off






Continuation of test: "Pressure in refrigerant circuit increases"






• The pressure in the refrigerant circuit depends on several factors. However, in general, the pressure should not exceed 20 bar (290 ps) at an ambient temperature of 20 to 25 °C (68 to 77 °F). Under extreme conditions (for example stop and go traffic at a high ambient temperature and high relative humidity), pressures up to 31 bar may occur due to the extremely high cooling output.

• At ambient temperatures below 25 °C (77 °F), pressure in refrigerant circuit does not normally exceed 16 bar (232 psi) coolant fans run and cool condenser).

• The Climatronic control module, calculates the pressure in the coolant circuit via the measured value of the A/C pressure/temperature sensor (G395) and displays it using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• At an absolute pressure of less than approximately 1.8 bar (26 psi) or greater than approximately 32 bar (464 psi), the Climatronic control module does not switch on the A/C compressor (the A/C compressor regulator valve is not activated). The A/C compressor is only switched on once the absolute pressure becomes greater than 1.8 (26 psi) bar or less than 16 bar (232 psi).

• Additional information regarding the pressure in the refrigerant circuit can be found in Guided Fault Finding using the Vehicle Diagnostic Tester in the "Guided Fault Finding" function.

• To prevent abrupt A/C compressor shutoff due to excessive pressure in refrigerant circuit or an excessive coolant temperature, the Climatronic control module regulates the A/C compressor output. As soon as pressure in refrigerant circuit exceeds 30 bar (absolute pressure), full A/C compressor performance is only enabled again after pressure has become less than 27 bar (391.6 psi), or coolant temperature exceeds 115 °C (239 °F) (it is switched off completely at 118 °C (244 °F)).