Click the image to see the laminated double-sided chart.

Urgent comfort problems drive AC service calls. HVAC technicians should upsell service calls to include a thorough energy-efficiency tune-up. Customers appreciate the extra benefits of electricity-cost savings and enhanced comfort that the tune-up delivers. The technician should work from a procedure to solve all the typical problems that affect air conditioning and heat pump systems.

  • The technician should first interview the building owner to learn about comfort problems, noise, temperature differences in rooms, and other observations.
  • Then the tech fixes obvious problems, like replacing filters, cleaning coils, and cleaning the blower as necessary. The system might contain obstructions, large duct leaks, or heating and cooling operating simultaneously. There’s no reason to test airflow or duct leakage while serious and obvious problems go unsolved.
  • The second step is to measure AC-system airflow because airflow is usually too low. The tech then finds ways to improve the airflow. For example, the return registers and main return may be much too small. In this case the tech would replace some of the ducts. Or, some flex duct branches may be offering too much resistance. So the tech would replace the flex duct with insulated smooth metal duct.
  • Next, the tech should measure duct leakage and seal the duct leaks. he ducts could be sufficiently airtight or they could be extremely leaky. The tech won’t know until he measures air leakage with a duct tester.
  • After that he or she should insulate ducts, located in attached garages, crawlspaces, attics, and unconditioned basements. Insulated ducts provide better comfort, prevent condensation during the AC season, and save a lot of electricity. The only time you really need insulation inside the thermal envelope is to prevent condensation damaging the ducts or home furnishings.
  • Finally, the tech can measure refrigerant charge and adjust it if necessary. For this step, the tech must have an EPA refrigerant license.
What we mean when we say “obvious problems”

It’s very important that the AC tech go through these steps in the order presented above to prevent one step from hindering another. For example, what if the tech sealed all the ducts and then realized he needed to replace of ductwork?

For more information, complete Saturn’s micro course titled, “AC and Heat Pump Tune-Up Procedure”

Since ducts are so vitally important to energy efficiency, also try Saturn’s mini course titled, “Duct Energy Efficiency.”

Saturn’s HVAC Systems Field Guide is a very good design and troubleshooting reference.

Airflow and Static Pressure in HVAC Systems Micro Course is a great introduction to diagnosing airflow problems.