Checking With Expansion Valve And Reservoir Without Regulated A/C Compressor

Test Prerequisites 

• Radiator and condenser are clean (clean if necessary).
• The ribbed belt for the A/C compressor and alternator tensioned correctly.
• All air ducts, covers and seals are OK and installed correctly.
• The doors reach their end position.
• Engine is warm.
• Evaporator and heater not drawing in secondary air (at maximum fresh-air blower speed).

With engine running and A/C system set to maximum cooling output, pay attention to the following points:

• The fresh air blower is running.
• The coolant fan must be running or it must be switched on.
• The recirculation/fresh air door must be in the "recirculation" position.
• Ambient temperature is greater than 15 ⁰ C.
• The A/C Evaporator Temperature Switch -E33- is installed correctly and its switch temperatures are correct.

Checking 

-- Switch off the ignition.

-- Connect pressure gauge set (A/C service station).

-- Take pressure gauge readings. There are two possible results A and B.

Ambient Temperature In Degrees Celsius	Pressure In Bar (Positive Pressure) In Refrigerant Circuit
+ 15 °C	3.9
+ 20 °C	4.7
+ 30 °C	6.7
+ 40 °C	9.1

• A- The pressure in the refrigerant circuit is lower than the pressure specified in the table. There is not enough refrigerant in the circuit.

- Search for leak with leak detection device.

- The pressure release valve is open, check coolant fan activation according to the wiring diagram.

Check refrigerant pipes and hoses to see if they are bent too sharply (cross-section constrictions) or have external damage. If no malfunction is found, flush refrigerant circuit.

• B - The pressure in the refrigerant circuit matches the table or is higher.

-- Start the engine.

-- Set A/C system to maximum cooling output.

-- Open doors.

-- Open vents in instrument panel.

The A/C compressor is driven by the engine via the magnetic clutch using the ribbed belt.

If the A/C compressor is driven, check refrigerant circuit:

-- Bring engine speed up to 2000 RPM.

-- Observe manometer battery:

Specified Values 

High-pressure side 

Increasing from pressure with engine not running to a maximum of 20 bar.

Low-pressure side 

Decreasing from pressure with engine not running down to 1.3 bar.