The 5 Readings Every Tech Must Know Well


In this episode of HVAC School, Bryan covers the “5 pillars of refrigerant circuit diagnosis” and why they matter. They are:

  • Superheat
  • Subcool
  • Suction pressure
  • Head pressure
  • Air temp split (delta T)


These 5 readings give you a holistic idea of the A/C system. Instead of getting hooked on checking only superheat and subcool all the time and dismissing potential diagnoses, you can use these five readings to get an idea of the health of several parts of the system. Making it a priority to take these five readings also promotes open-mindedness, which is perhaps one of the most vital qualities of a diagnostician.

The five pillars will give you the clues to diagnose overcharge or undercharge, a wide variety of restrictions, kinked suction lines, expansion valves failing open, improperly seated pistons, condenser fan issues, and so many more conditions.

Also, regularly check and calibrate your tools. These 5 readings won't be helpful if you aren't constantly making sure your tools are accurate.

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