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Home >> BMW >> 2017 >> 530i >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heating And Air Conditioning - Repair (G30) (2 Of 3) >> 64 50 Air Conditioning, Test >> Leak detection with forming gas (530i 2017-2022, 530i xDrive 2017-2022, 530e PHEV 2018-2022, 530e xDrive PHEV 2018-2022, 540i 2017-2022, 540i xDrive 2017-2022, M550i xDrive 2018-2022)

Leak detection with forming gas (530i 2017-2022, 530i xDrive 2017-2022, 530e PHEV 2018-2022, 530e xDrive PHEV 2018-2022, 540i 2017-2022, 540i xDrive 2017-2022, M550i xDrive 2018-2022)

NOTE: Leak detection with forming gas replaces the leak detection that is restricted in EU countries using UV.
Observe national regulations in all other countries!
Observe the NOTES  on repair work on the air conditioning!.
IMPORTANT: Compliance with the manufacturer's operating instructions provided in the equipment case is absolutely mandatory!
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! 
IMPORTANT: Wear personal protective clothing/equipment!
NOTE: Determine the customer's use behavior prior to leak detection!
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 air conditioning for approximately 10 minutes while the engine is running.

Necessary preliminary work: 

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 

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

IMPORTANT: Always perform the leak detection with a pressure of 5 bar at first! 
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. 
IMPORTANT: The leak detection may not be performed more than 3 h  after filling the refrigerant circuit with forming gas!
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.
IMPORTANT: Risk of damage! 
Maximum approved pressure: 10 bar 
Do not start  the engine during the entire procedure!
G08465865Courtesy 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.
NOTE: If the leak detector displays a leak, remove the sensor head from the leak for approximately 10s.
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.
NOTE: Replace the leaking component. Relieve the pressure from the refrigerant circuit prior to replacement.
IMPORTANT: Compliance with the instructions above is absolutely mandatory!
Non-compliance will significantly reduce the efficiency of leak detection!
G09852485Courtesy of BMW OF NORTH AMERICA, INC.
NOTE: The graphic shows the example of the refrigerant circuit on the F02 with the automatic rear air-conditioning system optional equipment.
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
    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
    1. Refrigerant line, front (vehicles with and without automatic rear air-conditioning system)
    2. Refrigerant line, rear (vehicles with automatic rear air-conditioning system)
    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 grille, center (3).
    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).

    G09852486Courtesy of BMW OF NORTH AMERICA, INC.
    G09852487Courtesy of BMW OF NORTH AMERICA, INC.
  3. Expansion valve: 

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

    G09852488Courtesy 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.
      G09852489Courtesy of BMW OF NORTH AMERICA, INC.
  5. Filler neck 

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

    G09852490Courtesy 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).

    G09852491Courtesy 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.
      G09852492Courtesy 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.

    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!
    G08465874Courtesy of BMW OF NORTH AMERICA, INC.

    Following the completed leak detection: 

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