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A/C System Diagnosing and Charging
 
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Pelican Technical Article:

A/C System Diagnosing and Charging

Nick Czerula

Time:

2 hours2 hrs

Tab:

$300

Talent:

****

Tools:

A/C recovery machine, charging equipment, thermometer

Applicable Models:

R56 MINI Cooper Hatchback (2007-13)
R56 MINI Cooper JCW Hatchback (2009-13)
R56 MINI Cooper S Hatchback (2007-13)

Parts Required:

Compressor, refrigerant

Hot Tip:

Work with engine warm when testing

Performance Gain:

Restore A/C system function

Complementary Modification:

Replace cabin microfilter

The heating and air conditioning system (climate control) on R56 models is available in two options. MINIs come standard with IHKS which is a manually controlled climate control system. IHKA or automatic climate control is available as an option. IHKA picks up where IHKS leaves off. The more advanced system automatically adjusts the temperature and climate to the inputted settings. The system continuously monitors outside temperature, inside temperature, sun radiation and even operates the air recirculation system which monitors the passenger compartment to keep it free from air pollution while driving.

The heater housings used in both systems are identical. However, additional sensors and a refrigerant circuit for A/C control are added to IHKA systems. Both systems operate using the air based temperature control method.

An A/C compressor with a magnetic clutch and internally controlled output are used on R56 models. The magnetic clutch activates and deactivates the A/C compressor, in connection with the IHKS / IHKA control modules and DME working together with the junction box electronics.

IHKS and IHKA versions are equipped with an evaporator temperature sensor to avoid evaporator icing. The sensor signal is used as the input variable for activating the A/C compressor by the DME or junction box.

In A/C mode, the refrigerant high pressure sensor is monitored by the DME. The DME uses the monitored value to cycle the A/C compressor on and off to maintain pressure below a maximum value.

The IHKA or climate control panel is located in the center dashboard. This is the control for your heating and ventilation system. The most common portion of this control to fail is the blower motor control. It may seem as if the blower resistor is faulty, but replacing it doesn't remedy the issue. This may be a faulty blower control. You will want to check the signal to the blower resistor at this point and confirm the signal is faulty. Other functions of this control can also fail over time, however those are not as common.

Most electrical components on MINI R56 models require programming using an advanced MINI scan tool when replacing. With that said, don't feel you can't replace these items yourself. You also have the option of swapping out used items, which will at times work with programming. I don't have experience with this method, due to my access to a MINI scan tool, but it is something to consider. I have been told programming of used items isn't always required, so this may be an option, but I cannot vouch for it working 100% of the time. If you have experience with used part installation, please share your experience as it will help the Pelican Parts community.

Remember your car may have been serviced before and parts replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Our vehicle may vary slightly from yours as models do change and evolve as they grow older. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

Although R134a at normal temperature is non-toxic, non-flammable and not explosive in air in any mixture ratio, it is still essential to follow various safety precautions.

The filled refrigerant circuit of the A/C system is subject to gauge pressure. When carrying out repairs on the A/C system, it is absolutely essential to evacuate the refrigerant. R134a refrigerant must be evacuated, cleaned and returned to the A/C system with an A/C service machine.

Do not weld or solder in rooms into which R134a may have leaked. Exposure to flames or high temperatures may give rise to toxic decomposition products (fluorine gas). For this reason, do not smoke either.

Avoid all contact with liquid or gaseous R134a or any other refrigerant. Wear protective goggles and gloves when working on the refrigerant circuit. If you are around refrigerant or come in contact with it, seek immediate medical attention.

As a gas, R134a is colorless, odorless and heavier than air. If it enters the atmosphere, this may result in imperceptible dangers. Ventilate rooms adequately; if necessary, turn on exhaust fans.

When servicing an A/C system, it is essential to have the greatest possible levels of cleanliness when working on or opening the system and the best possible evacuation (at least 30 minutes dehumidification from refrigerant circuit) before filling the system.

R134a absorbs moisture very easily. Seal opened lines, condenser, evaporator, compressor and drier bottle immediately with plugs. I suggest replacing the drier each time the system is opened or a major leak is being repaired. When replacing parts, remove the plugs immediately before the lines are connected. After each service of the A/C system, check that the service valve protective caps are hand-tight. They serve as additional seals.

Store filled pressurized refrigerant bottles in such a way that they are not exposed to direct sunlight or other heat sources.

Fresh air is drawn in through the hood gap and the cover for the windshield cowl panel.
Figure 1

Fresh air is drawn in through the hood gap and the cover for the windshield cowl panel. A maze in the intake channel beneath the covers for the windshield cowl panel serves the purpose of deflecting water. The air enters the vehicle interior through an opening in the bulkhead in the area of the battery carrier (red arrow).

Climate control performance test: Using a MINI scan tool, check for fault codes.
Figure 2

Climate control performance test: Using a MINI scan tool, check for fault codes. If any are stored, repair the issue first. Attach a thermometer to the seat headrest. Be sure ambient temperature is above 65 degrees F with the engine at operating temperature. First Heat passenger compartment: A/C button is not activated during the heating process. Close all windows and doors. Set air recirculation function. Select air distribution mode for footwell and defrosting. On vehicles with CID (central info display): select 100 % footwell for driver and front passenger and 100 % defrosting for driver. Maximum temperature setting. Maximum blower speed. Start engine. Second Cool passenger compartment: Once thermometer at headrest reaches 113 degrees F, turn the A/C ON. On vehicles with MAX A/C button: Activation of MAX A/C.
On vehicles without MAX AC button: Set maximum cooling power by means of following steps: Setting minimum temperature. Blower setting maximum. Only ventilation open. Close remaining flaps (air outlet only from center fresh air grille, left and right). After 5 minutes measure both ventilation temperatures with a thermometer at the same time (fresh air grille center, left and right). The measured temperature must be <=60 degrees F and the difference between right and left may not be greater than 35 degrees F. If one or both temperature specifications is not reached, drain off heating and air conditioning system. Evacuate and measure amount of refrigerant drawn off. If refrigerant was low, refill with correct amount. If amount was correct, check system pressure for issue.

Use the label (red arrow) on the radiator support to confirm your vehicles charge amount.
Figure 3

Use the label (red arrow) on the radiator support to confirm your vehicles charge amount. R56 models hold 490 (+/- 10) grams of R134 refrigerant.

Evacuate, vacuum and charge the A/C system through the service port located at the right front of the engine.
Figure 4

Evacuate, vacuum and charge the A/C system through the service port located at the right front of the engine. Follow the instruction supplied with your service tool when performing an evacuation, system vacuum or when charging (filling) the system. Expect a static system pressure of 75 psi. The compressor should come on with a minimum of 45 psi. When testing, the following pressure scenarios can be used to point you toward the issue (85 degrees F ambient temp):

  • Normal low pressure (21-35psi), Normal High pressure (199-275psi)
  • High and low pressure needles bouncing from low to normal indicates moisture in system.
  • Low pressure reading Low side (7-14psi), Low pressure reading High side (99-142psi)
  • Low refrigerant charge
  • Poor refrigerant circulation
  • High pressure reading Low side (30-50 psi), Low pressure reading High side (280-355psi)
  • Over-charged system
  • Expansion valve stuck open
  • Air in system


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