What does it mean when the engine RPM doesn't change with AC on?

[CamilaDella]

When the engine RPM remains unchanged with the AC on, it's maintained by increasing the fuel injection duration of the engine injectors to stabilize idle speed. Here's a detailed introduction about automotive AC refrigerant charging: 1. Precautions: There are two methods of AC refrigerant charging - high-pressure side charging and low-pressure side charging. These are completely different methods, with one charging liquid and the other charging gas. High-pressure side charging is typically used for initial charging, which involves liquid and is faster and safer. Low-pressure side charging uses gas, with a slower charging speed, and is generally used for replenishment. 2. Determination method: If bubbles appear in the sight glass, it indicates the need for refrigerant charging.