Checking My AC's Performance: A Simple Temperature Test

Yesterday I decided it was time to clean the AC coils on the downstairs unit and wanted to measure the  perfomance improvement with before and after temperature readings.

I recently left my AC vent thermometer in a car I sold and was forced to use a red digital meat thermometer and worked just fine. 

Using the red thermometer, I measured the air coming from the upstairs unit at 4 PM and found it to be 68 degrees. After cleaning the outside coils, the same vent measured 64 degrees. That's a significant difference.

However, even 64 degrees seemed too high, especially after measuring the downstairs air at 57 degrees. A 9 PM reading upstairs showed 57 degrees, confirming that the unit was working fine and that high attic temperatures were stealing 7 degrees from the cool air. It looks like it’s time to try to reduce the temperature in the attic. My first step will be to replace the attic exhaust fan. Stay tuned for updates!