• Stable support pad;
  • Adequate enclosure (does not obstruct airflow);
  • Sits level;
  • Fins undamaged and unobstructed;
    • Dog urine
    • Impact (hail or lawnmowers are common sources)
  • Within acceptable service life
  • Photograph data plate & record info:
  • Condition of suction and liquid lines;
    • Comment on missing insulation
    • Comment on frost on the suction (larger) line.
  • Refrigerant line penetration adequately sealed.
  • Electrical disconnect within sight of the unit;
  • No excessive noise at start up

Do not operate the AC system if the outside temperature is below 57° F!

AC compressors are designed to pump vapor. At lower temperatures the system will be full of liquid and operating it may damage various components. At lower temperatures, disclaim the AC system and recommend that it be serviced at the beginning of the cooling season.

Don't measure temperature differentials!

Measuring the temperature differential between the return and supply air (often called the “temperature split”) is not a good means of determining if the unit is functioning or cooling as needed. The results can vary with a number of factors. At the least, a unit would need to be freshly-serviced for the results of the measurement to be meaningful, and if it has been freshly serviced, there’s no need for an inspector to measure differentials. Inspectors are safest from liability if they stick to performing a visual inspection and run the system (as long as the outside temperature is 60° F or higher).


  • Response to thermostat;
  • Corrosion visible?;
  • Condensate-related equipment satisfactory;
    • Overflow and secondary overflow:
    • Discharge to floor drain;
    • Condensate pump operable;
    • Pump tray intact.
  • Temperature stratification
    • In multiple-story homes inspected during the heating (cold) season, you may want to mention in your report that temperature stratification can occur and lower portions of the house may be cooler than upper stories. This condition is more likely in homes with systems that were originally designed for central heating only. Because cool air is denser than warm air, larger ducts are typically required for optimal cool air  distribution.
  • Similar temperatures at different registers
    • Using an infrared thermometer, measure temperatures and different supply registers and mention any that are significantly different from the rest.

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