Doug - thanks for your input. The digital thermometer I used is a Jumper digital thermometer. The “House” symbol indicates object measurement mode. It seems to be accurate with other similar type measurements. The readings I got were taken right at the vent with both a/c’s running. Although this is not perhaps the right tool to use it’s what I had and I doubt it would be 20 degrees off.
I have the mobile tech from La Mesa RV coming next Saturday to fix my reversed furnace wiring and some other things. I will have them check both a/c units while they are here. I would imagine they have a more appropriate measuring device for the application.