Leaks, Finding Using Nitrogen Pressure Test

Special tools and workshop equipment required 

• Pressure Gauge Set with Pressure Reducer for Nitrogen (maximum reducing pressure: 13.5 bar)
• Service Coupling (can also be used from the A/C Service Station)
• Filler Hose
• Nitrogen Cylinder

Tools, Preparation

-- Connect the Pressure Gauge Set with Pressure Reducer for Nitrogen (maximum reducing pressure: 13.5 bar) -1- to the nitrogen cylinder -3- and the filler hose -2- (for example with a M12 x 1.5 -6G thread according to SAE J639).

Fig 1: Identifying Pressure Gauge Set With Pressure Reducer For Nitrogen (Maximum Reducing Pressure: 15 Bar)

Courtesy of AUDI OF AMERICA, LLC

-- Connect the Service Coupling with the filler hose -2-.

Procedure 

• Refrigerant circuit is completely assembled.
• Refrigerant circuit is completely evacuated.

-- If possible, evacuate the refrigerant circuit. Refer to REFRIGERANT CIRCUIT, EVACUATING .

Vehicles with electrical A/C compressor

-- De-energize the high-voltage system. Refer to the appropriate Service Information .

Vehicles with mechanical A/C compressor

-- Make sure that a vehicle with its refrigerant circuit filled with nitrogen is not started.

Continuation for all vehicles

-- Close the Pressure Reducer. Refer to Owner's Manual.

-- Raise the refrigerant circuit pressure slowly and in stages (maximum 13.5 bar).

-- Determine the leak location using noises.

-- Drain nitrogen via the Pressure Reducer. Refer to Owner's Manual.

-- Correct leaks.

-- Evacuate the refrigerant circuit after using nitrogen for at least 30min.