Try this: Increase outdoor temperature to 43°C while keeping cooling load constant. Notice how Compressor Work (W) increases and COP drops, even though the same amount of heat is removed from indoors.
Takeaway: An air conditioner moves heat; it doesn't create cold. Efficiency depends heavily on how hot it is outside.
Limitations: Illustrative steady-state energy balance only. Not a service guide or equipment predictor.
Ref: US DOE Energy Saver: Home Cooling