64 50... Leak detection with forming gas

Observe national regulations in all other countries!

Read and comply with the manufacturer's operating instructions provided with the special tool particularly with regard to accident prevention, health protection and environmental protection.

Only the basic procedure is described in the following! 

Certain user behaviors can lead to a loss of refrigerant from the refrigerant circuit even if there is no leak. This may occur if the customer has not used the air conditioning for a period of more than six months. This may cause O-ring to harden and refrigerant may leakage. In this case, it will be sufficient to fill the refrigerant circuit again and switch on the air conditioning for approximately 10 minutes while the engine is running.

Preliminary work needed: 

• If components of the refrigerant circuit are contaminated, clean the engine compartment. Otherwise, the sensor head of the leak detector will become contaminated. 

  Comply with notes on HANDLING HIGH PRESSURE CLEANER .

• DRAIN OFF  air conditioning system
• Fill the air conditioning with forming gas
• Set pressure to 5 bar

To reach the components of the refrigerant circuit with leak detector, specific parts must be removed depending on the vehicle.

Remove the following parts first immediately before the check of the respective components 

• Drive belt from air conditioning compressor
• Center fresh air grille
• Covers
• Trim panels
• Air ducts
• Intake silencer
• Bulkheads
• Parts of the interior equipment (automatic rear air-conditioning system)

In some vehicles it is necessary to open the air flaps of the automatic air flap control.

Delete fault memory after filling the refrigerant circuit.

This is absolutely necessary to find certain leaks, such as in the area of the O-rings.

If no leak is detected, repeat the leak detection with 10 bar. 

Forming gas consists of 95% nitrogen and 5% hydrogen. The leak detector will detect hydrogen. If this is leaking from the refrigerant circuit even though the pressure remains, the leak detection bears no results.

Maximum approved pressure: 10 bar 

Do not start  the engine during the entire procedure!

Fig 1: Checking Leak Detector

Courtesy of BMW OF NORTH AMERICA, INC.

Notes for handling the leak detector:

1. Sensor head should always stand vertical to the surface to be checked.
2. Sensor head must always be aligned to the center of the point to be checked. Slowly guide the sensor head around the point (e.g. connection point, sealing surface, etc.).
3. The optimal distance (A) between sensor head and surface to be checked should permanently be approximately 1 mm.

   Maximum distance (B) at points that are difficult to access approximately 5 mm.

4. Checking speed may not be more than maximum 2 cm per s.

Then check if the leak is still displayed at the same point. Repeat the process up to three times, to ensure that a leak is actually present at this point.

Non-compliance will significantly reduce the efficiency of leak detection!

Fig 2: Example Of Refrigerant Circuit On F02 With Automatic Rear Air-Conditioning System

Courtesy of BMW OF NORTH AMERICA, INC.

Refrigerant circuits on other vehicles may differ from the graphic.

Overview of positions to be checked: 

1. Air conditioning condenser
2. Connection point between air conditioning condenser and refrigerant line
3. 1. Expansion valve, front (vehicles with and without automatic rear air-conditioning system)
   2. Expansion valve, rear (vehicles with automatic rear air-conditioning system)
4. Air conditioning compressor
5. Filler neck high pressure and low pressure
6. Refrigerant pressure sensor
7. 1. Refrigerant line, front (vehicles with and without automatic rear air-conditioning system)
   2. Refrigerant line, rear (vehicles with automatic rear air-conditioning system)
8. 1. Evaporator, front (vehicles with and without automatic rear air-conditioning system)
   2. Evaporator, rear (vehicles with automatic rear air-conditioning system)
   NOTE: Refrigerant line connection points are identified by arrows.

   Checking sequence: 

   1. Check of components 1, 2, 3a, 4, 5, 6, 7a and 8a of the automatic front air-conditioning system.

      If no fault found: 

   2. Check of components 3b, 7b, 8b and connection points of the automatic rear air-conditioning system.
   1. Air conditioning condenser: 

      Damage caused by stone chipping, etc. is the most frequent cause of air conditioning condenser leaks (1):

      1. Visual inspection in the area of the radiator grille (2) and air inlet grill, center (3).
         Fig 3: Checking Radiator Grille And Center Air Inlet Grill

         Courtesy of BMW OF NORTH AMERICA, INC.
      2. Check damaged points first.
      3. Check the remainder of the air conditioning condenser.
   2. Connection point capacitor - refrigerant line 

      Check the connection point between the connection at the air conditioning condenser

      1. and refrigerant lines (2).
      Fig 4: Checking Connection Point Between Air Conditioning Condenser Connection

      Courtesy of BMW OF NORTH AMERICA, INC.
   3. Expansion valve: 

      Check the connection point between the expansion valve (1) and refrigerant lines (2).

      Fig 5: Checking Connection Point Between Expansion Valve And Refrigerant Lines

      Courtesy of BMW OF NORTH AMERICA, INC.
   4. A/C compressor: 

      Remove drive belt from air conditioning compressor.

      Check the following components on the air conditioning compressor:

      1. High-pressure connection
      2. Low pressure connection
      3. Pressure relief valve
      4. Radial shaft seal of the magnetic clutch: Turn the magnetic clutch several times hand force during the leak detection.
      Fig 6: Checking Air Conditioning Compressor Components

      Courtesy of BMW OF NORTH AMERICA, INC.
   5. Filler neck 

      Blow out the fuel filler neck (1) prior to checking.

      Fig 7: Fuel Filler Neck Location

      Courtesy of BMW OF NORTH AMERICA, INC.
   6. Refrigerant pressure sensor 

      Check the sealing surface between the refrigerant pressure sensor (1) and the refrigerant line (2).

      Fig 8: Checking Sealing Surface Between Refrigerant Pressure Sensor And Refrigerant Line

      Courtesy of BMW OF NORTH AMERICA, INC.
   7. Refrigerant lines: 
      1. Perform visual inspection
      2. Check damaged points first.
      3. Check bending points at points marked with an arrow. Leaks occur especially frequently at these points.
      4. Check the remainder of the refrigerant line.
      Fig 9: Checking Refrigerant Lines Bending Points

      Courtesy of BMW OF NORTH AMERICA, INC.
   8. Evaporator: 

      Remove the center fresh air grille.

      Compliance with the following settings is absolutely  required:

      • Recirculated-air mode On
      • Lowest blower speed
      • Lowest temperature
      • Set the air distribution to ventilation (air may only flow out of the center fresh air grille)
   Fig 10: Checking Center Fresh Air Grille

   Courtesy of BMW OF NORTH AMERICA, INC.

   Position sensor head (1) in air duct of middle fresh air grille (2) as illustrated and shift slowly from inside to outside above and below air flap (3). Carry out this operation on the left and right fresh air grilles.

   IMPORTANT: Some vehicles have an expansion valve directly next to the fresh air intake for the passenger compartment.

   In this case the expansion valve must be covered!

   Following the completed leak detection:

   • EVACUATE AND FILL  heating and air conditioning system