Would it actually be that inefficient? I honestly don't know, but am curious if the tech has changed that significantly. Consider lifecycle costs (both financial and resources) before replacing it; might just need a clean and service.
In my case at least, replacing a 70s Carrier "window A/C" (that was actually embedded in a hole in the wall instead of a window) with a modern ductless mini-split with inverter-powered compressor resulted in almost 70% lower power consumption, not to mention the fact that the new unit is virtually silent.
