You work in a manufacturing plant, and your company has an administrative office across town. Your boss sends you over there to figure out why the offices have not been staying cool during the summer. The office manager tells you, "I’ve had the HVAC contractor out here three times since June to check the Freon. He does his thing, we're good for a while, and then it gets hot again."

Has the office manager told you anything useful, and what should you do next?

It sounds like the office manager doesn't know what services the HVAC tech has performed.

Most systems today use refrigerants other than Freon (a brand name). In fact, this is the last year in which new HVAC systems can use Freon. Ten years hence, nobody can legally use Freon. You need a permit to work on refrigerant systems, and you must account for lost refrigerant. Gone are the days when you just added more to a leaky system.

Among the many things the HVAC tech does, cleaning the coils and filters are two services that nature can quickly undo. If the HVAC tech has had to perform these two services each time, then your system is sucking in debris. Some mechanical work on the intakes may fix this. Read the service reports, and see if you can get the technician to come out, walk you through the HVAC servicing, and explain what problems keep arising.

Low voltage, voltage imbalance, and other power anomalies can also cause HVAC underperformance or compound problems from other causes. Use a power analyzer to determine what your power quality conditions are.