Test Prerequisites

• Radiator and condenser are clean (clean if necessary)
• Thermal insulation at expansion valve OK and properly installed. Refer to [For engine(s) BPY, CCTA, BUB, CBFA] Removal and Installation .
• Ribbed belt is OK and properly tensioned. Ribbed belt for A/C compressor and generator are OK and correctly tensioned. Refer to [For engine(s) BPY, CCTA, BUB, CBFA] Removal and Installation .
• All air ducts, covers and seals OK and properly installed
• Fault finding on the electrical equipment and vacuum system found no malfunction. Refer to [For engine(s) BPY, CCTA, BUB, CBFA] Diagnosis and Testing .

• 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 for 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 [For engine(s) BPY, CCTA, BUB, CBFA] Removal and Installation .
• 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 [For engine(s) BPY, CCTA, BUB, CBFA] Description and Operation .
• The air flaps in the heater and A/C unit reach their end position. Refer to [For engine(s) BPY, CCTA, BUB, CBFA] Description and Operation .
• Fresh-air intake ducts beneath hood and in passenger compartment as well as corresponding water drain valves OK. Refer to [For engine(s) BPY, CCTA, BUB, CBFA] Diagnosis and Testing .
• Engine is warm
• Vehicle not exposed to direct sunlight
• Ambient temperature greater than 15°C (60°F).
• All instrument panel vents open
• With engine running and maximum cooling output set on air conditioning system:

Refer to [For engine(s) BPY, CCTA, BUB, CBFA] Description and Operation .

Set Maximum Cooling Output 

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

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

-- Set temperature selection "LO" for driver's and passenger's side.

Setting on heater controls:

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

-- Temperature dial in the "Cold" position.

-- Rotary fresh-air blower control 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 minute 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?