Repair instruction for plausibility of the air-conditioning system sensors

Check the plausibility of the air-conditioning system sensors

Precondition

• Provision of a thermometer with digital display.
  
• Perform the check in a suitable work bay with an ambient temperature between 20 °C (68 °F) and 30 °C (86 °F).
  

Coolant pressure sensor

Check the refrigerant pressure sensor as follows.

1. Run engine at idle speed.
   
2. Switch off the air conditioner.
   
3. Observe the coolant pressure sensor display in the test module; a static pressure sets in.
   
4. Press the MAX button.
   
5. Observe the display for the coolant pressure sensor in the test module; the value must rise.
   

Evaporator temperature sensor

Check the evaporator temperature sensor as follows.

1. Run engine at idle speed.
   
2. Switch off the air conditioner.
   
3. Observe the evaporator temperature sensor display in the test module; an evaporator temperature sets in.
   
4. Press the MAX button.
   
5. Observe the display for the evaporator temperature sensor in the test module; the value must fall.
   

Outside temperature sensor

Check the outdoor temperature sensor as follows.

Important

If the vehicle is move from a cold environment to a warm environment, the outside temperature is adapted with a long delay! Rapid adaptation of the temperature value only takes place as of a speed of 80 km/h.

1. Measure the outside temperature with a thermometer.
   
2. Compare the measured temperature with the display of the outdoor temperature sensor in the test module. The values must be approximately the same.