Air-conditioning efficiency measurement

Air-conditioning efficiency measurement (R134a)

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Before the air-conditioning efficiency measurement, a number of conditions must be met:

1. Ensure the electrical system integrity by checking the fault code memory (no faults in the fault code memory).
   
2. Provide a thermometer with a separate display element.
   Position a thermometer with a separate display element approx. 5 cm under the headlining at the height of the B-pillar. Route the display element from the vehicle interior outwards.
   
3. Perform the check in a suitable work bay with an ambient temperature between 20 °C (68 °F) and 30 °C (86 °F).
   Heat up the vehicle interior:
   
   • The A/C button is not activated on heating up
     
   • Close all windows and doors
     
   • Set the recirculated-air mode
     
   • Select air distribution footwell and defrosting
     
   • Maximum temperature setting
     
   • Maximum blower speed
     
   • Run the engine at approx. 2000 rpm until operating temperature is reached, then idle speed
     

Air-conditioning efficiency measurement:

Once the vehicle interior has reached a temperature of 50 °C (122 °F), switch on the air-conditioning compressor. After 3 - 4 minutes, the temperature at the evaporator temperature sensor must be ≤ 15 °C (59 °F).