64 50... Leak detection with forming gas

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-rings to harden and refrigerant may escape. In this case, it will be sufficient to fill the refrigerant circuit again and switch on the heating and air conditioning system for approximately 10 minutes while the engine is running.

Necessary preliminary work 

• 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 AND INSTRUCTIONS ON HANDLING HIGH PRESSURE CLEANER

• DRAIN OFF AIR CONDITIONING SYSTEM 
• Fill the air conditioning system 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 duct
• Intake silencer
• Bulkheads
• Parts of the interior equipment (automatic rear air-conditioning system)

With some vehicles, the air flaps of the automatic air flap control (LKS) must be opened.

F01 h, F02 h, F02, F03, F04: 

Before filling the refrigerant circuit with forming gas, perform test module  "Draining/Filling of refrigerant circuit".

Vehicle-specific notes I01 

Equipment specification with and without  heat pump:

To access the connections for the refrigerant lines, remove front luggage compartment well.

Fig 1: Identifying Heat Pump Connector

Courtesy of BMW OF NORTH AMERICA, INC.

Equipment specification with  heat pump:

Carry out the following steps before filling the refrigerant circuit with forming gas: 

1. Switch on terminal 15:  To do so, press the Start/Stop button without operating the brake pedal. 
2. Switch off blower at IHKA controls  (so that air conditioning compressor cannot start up).
3. Switch on low-beam headlight  (so that terminal 15 can switch off automatically after a certain period).

   If necessary, charge the high-voltage battery (12 V battery is charged via the high-voltage battery).

4. Pull off connector (1). 

This state must last for the duration of the entire leak detection process! 

Equipment specification with and without  heat pump:

After filling the refrigerant circuit with refrigerant, delete fault memory! 

Maximum approved pressure: 10 bar 

Do not start  the engine during the entire procedure!

Fig 2: Checking Distance Between Sensor Head And Surface

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.

Fig 3: Example Of Refrigerant Circuit On F02 With Automatic Rear Air-Conditioning System

Courtesy of BMW OF NORTH AMERICA, INC.

Refrigerant circuits of BMW i vehicles differ a lot from the figure 

Overview components refrigerant circuit I01

Overview components refrigerant circuit I12

Pay attention to leak detection in these vehicles 

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)

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 grille, center (3).
   2. Check damaged points first.
   3. Check the remainder of the air conditioning condenser.
      Fig 4: Identifying Air Conditioning Condenser Leak, Radiator Grille And Air Inlet Grille, Center

      Courtesy of BMW OF NORTH AMERICA, INC.
2. Connection point capacitor - refrigerant line 

   Check the connection point between the connection at the air conditioning condenser (1) and refrigerant lines (2).

   Fig 5: Identifying Air Conditioning Condenser And Refrigerant Lines

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

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

   Fig 6: Identifying 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 coupling: Turn the magnetic coupling several times by hand during the leak detection.
      Fig 7: Identifying High And Low Pressure Connection, Pressure Relief Valve, Radial Shaft Seal Of Magnetic Coupling

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

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

   Fig 8: Identifying Fuel Filler Neck

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6. Refrigerant pressure sensor 

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

   Fig 9: Identifying 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 10: Identifying Refrigerant Lines

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

   Remove the center fresh air grille.

   Compliance with the following settings is absolutely  required:

   • Air recirculation function On
   • Lowest blower speed
   • Lowest temperature
   • Set the air distribution to ventilation (air may only flow out of the center  fresh air grille)

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

Fig 11: Identifying Sensor Head In Air Duct Of Middle Fresh Air Grille

Courtesy of BMW OF NORTH AMERICA, INC.

Following the completed leak detection:

• EVACUATE AND FILL HEATING AND AIR CONDITIONING SYSTEM