As long as an inspector states that he did not do something, and why, it is incumbent on the client to question it further. Negligence and incompetence do not apply here, just a business policy practice of the individual inspector. In practical terms, there is no need to run an air conditioner when the temperature is 65 degrees or under. Who really does that? For that matter, 70 degrees is still below the need to turn on an A/C system. There are many inspectors who feel comfortable with running the heat first and getting the interior temperature up to "the low to mid seventies". As long as the chassis of the condenser unit is at least 60 degrees, you should be able to run the A/C and get a good idea of efficiency. Turning an A/C system on is not good enough. The client deserves to know if there is a reasonable cooling function in the system. It is virtually impossible to assess some kind of cooling function unless you bring the ambient interior temperature well above the 65 degree mark. As far as damaging the condenser, 60 degrees is usually the minimum outdoor temperature for visual inspections. There are reports that older systems (15 years plus) can be damaged if the temperature is below 60 degrees. It seems to make sense. If an older unit is inspected in April, it may have been idle for 7 months. If an inspector were to "fire up" a unit in, let's say, 45 degree weather, they run the risk of being blamed for damaging the unit. Common sense seems to be the best advice here. Forcing an A/C system to perform in abnormal conditions is not in the best interests of the client.