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What should the temperature drop across the evaporator coil be?

  1. 10 to 15 degrees Fahrenheit

  2. 15 to 22 degrees Fahrenheit

  3. 20 to 25 degrees Fahrenheit

  4. 25 to 30 degrees Fahrenheit

The correct answer is: 15 to 22 degrees Fahrenheit

The appropriate temperature drop across the evaporator coil in a residential air conditioning system is typically in the range of 15 to 22 degrees Fahrenheit. This temperature drop indicates efficient heat exchange, where the refrigerant absorbs heat from the indoor air as it passes over the evaporator coil, resulting in a significant cooling effect. When the temperature drop falls within this range, it demonstrates that the system is operating effectively. If the drop is lower than 15 degrees, it may suggest an issue such as insufficient airflow, a dirty coil, or low refrigerant levels. Conversely, a drop exceeding 22 degrees may indicate a possible overcharge of refrigerant or inadequate airflow, signaling the need for further inspection. Understanding this temperature drop is critical for home inspectors assessing HVAC systems, as it helps identify potential malfunctions that might affect overall efficiency and comfort in the home.