There could be a few reasons why your air conditioner is blowing normal air when switched on before moving:
Engine Load: When you start your vehicle, the engine needs to warm up and reach its operating temperature before it can produce enough power to run all the accessories, including the air conditioner. Until the engine reaches the appropriate temperature, it might not generate enough power to fully engage the AC compressor, resulting in normal air being blown from the vents.
Idle RPM: In some vehicles, the engine's idle RPM (revolutions per minute) might be set lower to conserve fuel when the car is not moving. A lower idle RPM could lead to insufficient power to drive the AC compressor effectively. As you start moving and the engine RPM increases, the AC compressor might engage, and the air conditioner will then start working properly.
AC Pressure: Modern vehicles have safety mechanisms to protect the air conditioning system. If the refrigerant pressure is too low or too high, the AC compressor may not activate to avoid potential damage. Once the car starts moving, the airflow through the condenser can help regulate the pressure, allowing the AC compressor to kick in.
Electrical System: Sometimes, an issue with the electrical system can prevent the AC compressor from turning on when the car is stationary. Moving the vehicle can jostle the electrical connections and resolve the problem temporarily.
System Calibration: Some car AC systems are designed to delay the AC compressor engagement when the car is first started to reduce the load on the engine during cranking. It may take a short period of time for the system to calibrate and begin blowing cold air.
Low Refrigerant: If your car's AC system has a refrigerant leak and the refrigerant level is too low, the AC compressor may not operate to avoid damage. As you start driving, the compressor might engage intermittently if there is still enough refrigerant to allow some cooling.
If this issue persists or worsens, it's essential to have your vehicle's AC system inspected by a qualified mechanic. They can diagnose the specific problem and recommend the appropriate repairs to ensure your AC functions correctly.