You can safely check a few basic things yourself, such as whether the aircon settings are correct, the vents are open and the cabin air filter needs attention according to your vehicle’s manual. However, weak cooling, refrigerant leaks, unusual compressor noises, electrical faults and persistent unpleasant smells may require professional diagnosis. Avoid handling refrigerant or dismantling aircon components yourself. If simple checks do not resolve the problem, a qualified car aircon technician can identify the cause and recommend the appropriate repair.