Measures to Be Taken If Readout Does Not Match Specification

Measures To Be Taken If Readout Does Not Match Specification

- Select display group "001" in "Read measuring value block" function Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding" function.
- Repeat cooling performance test. A/C Cooling Output, Checking







Increase in pressure in refrigerant circuit

- Open hood.
- Repeat cooling performance test. A/C Cooling Output, Checking







NOTE:
- Pressure in refrigerant circuit is governed by various factors of influence. However, at an ambient temperature between 20 to 25 degrees C the pressure should not exceed more than 20 bar. Due to high coolant performance, pressures up to 31 bar may occur under extreme operating conditions (e.g. in southern countries with high ambient temperatures, "stop and go" traffic and high humidity).
- At ambient temperatures below 25 degrees C, pressure in refrigerant circuit does not normally exceed 16 bar (radiator fan runs and cools condenser).
- Climatronic Control Module J255 calculates pressure in refrigerant circuit via the duty cycle (read measuring value block, display group "001", display field "3").
- At a duty cycle less than 12.5% (corresponds to approx. 1.8 bar absolute pressure) and greater than 87.5% (corresponds to approx. 32 bar absolute pressure),does not switch on compressor (A/C Compressor Regulator Valve N280 is not activated). Compressor is only switched on again after duty cycle has become greater than 12.5% (corresponds to 1.8 bar absolute pressure) or less than 48% (corresponds to 16 bar absolute pressure).
- To prevent abrupt compressor shut-off in case of excessive pressure in refrigerant circuit or excessive coolant temperature,regulates compressor performance:
- As soon as pressure in refrigerant circuit exceeds 30 bar (absolute pressure), full compressor performance is only enabled again after pressure has become less than 27 bar.
- As soon as coolant temperature exceeds 115 degrees C (full shutdown at 118 degrees C).
- If pressure in refrigerant circuit was greater than 32 bar (duty cycle greater than 87.5%), compressor is only switched on again by if pressure drops below 29 bar (duty cycle less than 84%).
- Further notes on pressure in refrigerant circuit can be found in ("Read measuring value block", display group "001") and Vehicle Diagnosis, Testing and Information System VAS 5051 in "Guided Fault Finding" function.