Determining Malfunction if Specified Values Are Not Obtained

Determining Malfunction if Specified Values Are Not Obtained






• Only the Climatronic control module (J255) display and control head, part number 8P0 820 043 from index AE through index AH with software version 0430 (Audi A3 and Audi A3 Sportback) or from index BC or BD starting with software version 0800 (Audi A3 Cabrio) may be installed on vehicles with a 2.0L TFSI engine (engine code CAWB). If vehicle with this engine have a Climatronic control module with software version 0420 and 0700, then the control of the compressor is shut off by the Climatronic control module due to an unfounded request from the engine control module (the control current is limited to 300 mA, until the pressure in the refrigerant circuit exceeds approximately 7.5 bar) and the A/C cooling performance is unacceptable to the customer. Refer to the Electronic Parts Catalog and to => [ Climatronic Control Module, Applications ] Climatronic Control Module, Applications.

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 at an ambient temperature of 20 to 25 °C. Pressures up to 31 bar may occur due to extremely high performance under severe conditions (such as in southern countries with a hot climate, "stop and go" traffic and high humidity).

• At temperatures below 25° C, the pressure in the refrigerant circuit generally does not rise above 16 bar (the coolant fans run and cool the condensers down).

• The Climatronic Control Module (J255) calculates the refrigerant circuit pressure via the duty cycle.

• At a duty cycle less than 10% (corresponds approximately 1.2 bar absolute pressure) and greater than 78% (corresponds approximately 32 bar absolute pressure), Climatronic Control Module does not switch on the compressor ( A/C Compressor Regulator Valve (N280) is not activated). The A/C compressor is only switched on again after duty cycle has become greater than 12% (corresponds to 1.8 bar absolute pressure) or less than 48% (corresponds to 16 bar absolute pressure).

• If the pressure in the refrigerant circuit or the engine coolant temperature is too high, Climatronic Control Module regulates the A/C compressor performance (to avoid sudden compressor cut-off): As soon as the refrigerant circuit pressure goes above 30 bar (absolute pressure). The full A/C compressor output will be released once after the pressure is less than 27 bar or when the coolant temperature goes above 115 °C (the A/C compressor switches off completely at 118 °C).

• If the pressure in the refrigerant circuit was greater than 32 bar (duty cycle greater than 78%) the A/C compressor is switched on again by Climatronic Control Module, if pressure drops below 29 bar (duty cycle is less than 74%).

• Additional information regarding the pressure in the refrigerant circuit can be found in "Guided Fault Finding" using Vehicle diagnosis, testing and information system (VAS5051B) in "Guided Fault Finding" function.