Test Requirements

• Radiator and condenser are clean (clean if necessary).
• Thermal insulation at expansion valve OK and properly installed, refer to EXPANSION VALVE for the vehicle-specific Repair Information.
• Ribbed belt is OK and properly tensioned. Ribbed belt for A/C compressor and generator are OK and correctly tensioned, refer to RIBBED BELT, REMOVING AND INSTALLING for the vehicle-specific Repair Information.
• All air ducts, covers and seals OK and properly installed.
• Fault finding on the electrical equipment and vacuum system found no malfunction.

• The A/C system OBD cannot find malfunctions with the Vehicle Diagnostic Tester in "Guided Fault Finding". The measured value block does not show any shut-off condition from the A/C compressor (only on vehicles with "A/C system" OBD).

• Air flow through dust and pollen filter not obstructed by dirt, refer to DUST AND POLLEN FILTER for the vehicle-specific Repair Information.
• The heater and A/C unit does not draw in any secondary air at the highest fresh air blower speed. Evaporator and heater not drawing in secondary air at maximum fresh-air blower speed, refer to GENERAL INFORMATION for the vehicle-specific Repair Information.
• The air flaps in the heater and A/C unit reach their end position, refer to GENERAL INFORMATION for the vehicle-specific Repair Information.
• Fresh-air intake ducts beneath hood and in passenger compartment as well as corresponding water drain valves OK, see vehicle specific Repair Information, refer to AIR DUCTS AND AIR DISTRIBUTION IN PASSENGER COMPARTMENT OVERVIEW .
• The engine is warm.
• Vehicle is not exposed to direct sunlight.
• Ambient temperature greater than 15 °C (60 °F).
• All instrument panel vents are open.
• With engine running and maximum cooling output set on air conditioning system:

Refer to COOLING OUTPUT TEMPERATURE, CHECKING .

Maximum cooling output, setting

Setting on Front A/C Display Control Head -E87-.

-- Preselect "Auto" mode (A/C compressor on).

-- Set the temperature preset "LO" for the driver and front passenger sides.

Setting on heater controls:

-- A/C button and Rec- or recirculated air button pressed.

-- Temperature dial in the "Cold" position.

-- Fresh-air blower dial in "4" position.

• The Coolant Fan -V7- runs (the fans run) (at least in level 1).*

• The Fresh Air Blower -V2- runs at maximum speed.
• Recirculated/fresh-air door set to "air recirculation mode" (within 1 min. after starting vehicle, air-flow door is closed and recirculated air door opened).*
• Is the coolant shut-off valve closed?*
• Are the valves on the pump valve unit closed and the coolant circulation pump is not pumping? *