Thermometer Trick for Vents

https://brooksgaci427.yousher.com/heat-safety-steps-while-waiting-on-ac-repair-from-comfort-experts-in-a-north-fort-worth-heat-wave

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