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.
• All air ducts, covers and seals OK and properly installed.
• Fault finding on the electrical equipment and vacuum system found no malfunction, refer to DIAGNOSIS AND TESTING for the vehicle-specific Repair Information.

• 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 PASSENGER COMPARTMENT FORCED AIR VENTILATION, CHECKING for the vehicle-specific Repair Information.
• The air flaps in the heater and A/C unit reach their end position, refer to DOOR MOTORS, ELECTRIC MANUAL CLIMATE CONTROL LOCATION OVERVIEW or DOOR MOTORS, CLIMATRONIC LOCATION OVERVIEW 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 CONDENSATION WATER DRAIN, CHECKING .
• 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:

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? *