If your air conditioning (AC) system starts getting hot while parked and then blows cold once you start driving, it could indicate an issue with the AC system or the engine cooling system of your vehicle. Here are a few possible explanations for this behavior:
Low refrigerant levels: Low refrigerant levels in the AC system can cause the AC to blow hot air when the vehicle is idling or parked. As you start driving, the increased RPM (revolutions per minute) of the engine can result in improved compressor performance, leading to colder air. However, low refrigerant levels may indicate a leak in the system, and it is recommended to have it inspected and repaired by a qualified technician.
Engine cooling system issues: The engine cooling system helps regulate the temperature of the engine. If there are problems with the cooling system, such as a malfunctioning radiator fan or a faulty thermostat, the engine may overheat, causing the AC to blow hot air. Once you start driving and air flows through the radiator, the engine cooling system improves, and the AC may begin to blow cold air again.
Faulty AC compressor: The AC compressor is responsible for compressing and circulating the refrigerant in the system. If the compressor is failing or experiencing issues, it may not function properly when the vehicle is idling, resulting in hot air blowing from the AC vents. Driving at higher speeds can sometimes provide better compressor performance, leading to colder air.
It is important to have your vehicle inspected by a qualified mechanic to diagnose the specific cause of the issue. They will be able to evaluate the AC system and the engine cooling system to identify any faults and recommend the necessary repairs.