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Leak detection with forming gas

NOTE: Leak detection with forming gas replaces UV leak detection, which is only permitted to a limited extent in EU countries.
In all other countries, observe country-specific regulations!

OBSERVE THE NOTES ON REPAIR WORK ON THE AIR CONDITIONING! .

Attention! 

It is essential that the manufacturer's operating instructions included with the device be observed!

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 general procedure is described here! 

Attention! 

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 leakage. In this case, it is sufficient to refill the refrigerant circuit and turn on the air conditioning system for approx. 10 min with the engine running.

Preliminary work needed: 

To reach components of the refrigerant circuit with leak detector, certain parts may have to be removed, depending on the vehicle.

Only remove the following parts immediately before testing the respective component: 

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

BEV and Plug-in Hybrid Electric Vehicles only: 

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

Attention! 

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  .

Attention! 

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 escapes from the refrigerant circuit despite pressure being maintained, leak detection is inconclusive.

Attention! 

Risk of damage! 

Maximum permissible 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 move 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 indicates a leak, keep the sensor head away from the leak point for approx. 10 seconds.
Then check whether a leakage is indicated again at the same place. 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.

Attention! 

Compliance with the instructions above is absolutely mandatory!

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

G06886302Courtesy of BMW OF NORTH AMERICA, INC.
NOTE: The illustration shows an example of the refrigerant circuit of the F02 with optional equipment rear passenger compartment air conditioning.
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, e.g. from stone chipping, is the most frequent cause of leaks in the air conditioning condenser (1):

    1. Visual inspection in the area of the radiator grille (2) and air inlet grill, center (3).
    2. Check damaged points first.
    3. Check the remainder of the air conditioning condenser.
    G09852486Courtesy 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).

    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. Air conditioning 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.
    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.
    G06886309Courtesy of BMW OF NORTH AMERICA, INC.
  8. Evaporator: 

Remove the center fresh air grille.

Compliance with the following settings is absolutely  required:

G09852493Courtesy of BMW OF NORTH AMERICA, INC.

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

Attention! 

On some vehicles, the expansion valve is located directly next to the fresh air intake for the vehicle interior.

In this case, cover the expansion valve!

Following the completed leak detection:

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