How and why do car air conditioning systems fail?

an evaporator core from a car air conditioner system

Modern car air conditioning systems can last for many years if they are checked, used, and serviced regularly. However, these systems can and do fail for reasons that do not always involve a lack of regular service. Let us look at these reasons first-

The system just stops working or works just some of the time

This can happen for several reasons. Let us look at some possible causes-

  • The refrigerant gas has leaked out as the result of damage to hoses, or other parts. Refrigerants can also leak out through damaged rubber seals, hose connections, or through the rubber of high-pressure rubber hoses because hoses become brittle over time. This can allow refrigerant to escape through the hose itself, even if it is not punctured or broken
  • Failed or defective pressure switches can prevent the system from working, or from working reliably
  • Damaged or broken wiring can prevent the compressor clutch from working, or from working reliably
  • A broken or defective thermostat can deactivate the air con system unexpectedly, or intermittently
  • Blown or damaged fuses can also prevent the compressor clutch from working
  • Defective or broken control switches may deactivate the system, or prevent a user from activating the system

Other causes that involve a lack of regular service, or improper serving, could include the following-

  • An improper car air conditioning regas procedure can cause the evaporator to freeze up. This will usually deactivate the climate control system until the evaporator thaws out
  • Charging the system with the wrong refrigerant can cause major failures. In some cases, the compressor can seize up.In other cases, the wrong refrigerant will damage rubber seals, thus causing major refrigerant leaks.

NOTE: Car air conditioning systems have special fittings to make it impossible to charge a system with the wrong refrigerant. However, some online retailers illegally sell adapters that bypass this protection.

  • Adding the wrong lubricating oil to some refrigerants can destroy the compressor in very short order
  • Improper recharging procedures can allow moisture to enter the system.This always causes rust to form in the system, which usually destroys the compressor
  • Mixing different refrigerants during improper recharging procedures can cause fatal damage to the compressor. This usually happens when the incorrect equipment is used to evacuate and/or recharge the system
  • Undercharging the system could cause the system not to work, or to not work efficiently

From the above, it should be clear that car air conditioning system service and repairs is a specialised field. In fact, it is illegal for uncertified persons to work on car air conditioning systems.

Therefore, we recommend that you visit Find a Mechanic to find certified car air conditioning service centres near you.

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