A diagnostic fee, also known as a service call fee, is a typical charge used by HVAC companies when a technician is called out to your home to diagnose any and all problems with your furnace or air conditioner. The service call charge covers the technician’s time, knowledge and any gas or other travel expenses associated with assessing the problem. It’s basically a service fee for the technician’s professional evaluation to identify the cause of the malfunction.
It’s like a doctor’s appointment. They must examine you to help figure out what’s wrong before proposing treatment. Similarly, the HVAC technician must diagnose your system to figure out the repair or maintenance course of action.