Testing AC Systems

Home inspectors have all been taught that AC systems should not be tested when outside temperatures are below 60 Fahrenheit. This is still a good rule of thumb even though some argue most AC systems (standard and heat pumps) now use scroll compressors, so they could be tested at lower temperatures. Nevertheless, I think testing AC systems at temperatures lower than 60 is taking an unnecessary risk; I know I don’t want to buy the homeowner a new compressor.