I agree Gary. To each his own. I wasn’t saying that you were wrong I was just saying that those of us who measure differentials are not wrong
Me too Roy. And the only time I report it is if it is clearly outside that range after a couple of hours of running with doors and windows shut. I will put a photo of my infrared thermometer, at the return and supply, in the report in that case.
Cold plenum is pretty much enough for me.
Needs a tuneup every year anyway and if not documented needs the tech.
I take, notate it and then include a note which clarifies that it doesn’t tell you much. A/C units pose some of the biggest limitations for inspectors doing limited visual. If its abnormally low or high it might focus your attention but there are plenty of other components to check which will also draw out potential problems.
Ain’t it grand… 
Joseph A., don’t think I was getting on your case.
Joe F. has been on this for many years and still can’t see the light…
Why he still holds this old wives tale as truth after all the documented FACT I have posted…
If you have any questions, you can call me any time. I’m not going through this crap again…
BTW: I’m more politically correct on the phone…
Listen up hard head I told you come ride with me I will make you a real inspector and have you working again:D:D
Come go ride with me:D:D
Oh really?!
That is true some of the time. But who need to be 100% correct in this business all the time, right?