BMW X3 Service & Repair Manual: Leak detection with forming gas

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!

IMPORTANT: Compliance with the manufacturers operating instructions provided in the equipment case is absolutely mandatory! Read and comply with the manufacturers 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!

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 notesI01:

Equipment specification with and without heat pump: To access the connections for the refrigerant lines, remove front luggage compartment well.

Equipment specification with heat pump:

HVAC

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 nec., 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!

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!

HVAC

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 10 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.

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!

HVAC

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.

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
    1. Expansion valve, front (vehicles with and without automatic rear air-conditioning system)
    2. Expansion valve, rear (vehicles with automatic rear air-conditioning system)
  1. Air conditioning compressor
  2. Filler neck high pressure and low pressure
  3. 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.

HVAC

2. Connection point capacitor - refrigerant line

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

HVAC

3. Expansion valve:

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

HVAC

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.

HVAC

5. Filler neck

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

HVAC

6. Refrigerant pressure sensor

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

HVAC

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.

HVAC

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)

HVAC

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!

Following the completed leak detection:

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