Thermometer Trick for Vents

https://johnathanvuwd525.lumenforgex.com/posts/fall-ac-care-in-north-fort-worth-from-the-comfort-experts-team-to-prevent-spring-ac-repair

Thermometer Trick for Vents Quick tip from our house: put a cheap kitchen thermometer in a supply vent after the AC runs 15 minutes, then check the air at the return. We see about an 18 degree drop when things are healthy