Tech Tips

As we discussed in an earlier podcast, a TXV maintains a specified and constant superheat at the evaporator coil outlet. It does this through a balance of forces between the bulb pressure (opening force), equalizer pressure (closing force), and spring pressure (closing force). We can actually adjust the spring pressure on some valves. But why […]

Most techs know that you shouldn’t fill a recovery tank more than 80% with liquid-based refrigerant. Many know that the WC rating stands for “water capacity.” So, you need to adjust for the density of the actual refrigerant rather than just using 80% of WC. I hope most of you know that the TW marking […]

Sometimes, you may have to replace a fancy thermostat with a simple one. It may be because the customer got fed up with all the options, or maybe the basic stat is the only thing on your truck. No matter the reason, you need to make sure the new thermostat can do the old one’s […]

First, here’s a quick summary of the role of oil in the refrigerant circuit: The compressor requires oil for the lubrication of the moving parts in the compressor. We would keep 100% of the oil in the compressor if we could. However, that is generally unrealistic. So, we need to utilize oils and oil strategies […]

It was an awkward conversation, bringing a technician nearly twice my age into my office for a talk. “I’m good at fixing units. I’m not some fancy-talking sales tech,” the technician half-mumbled as I sat looking at him. “The customer complained that you made them feel uncomfortable, you were unfriendly, and you tracked dirt in […]

Photo by Ulises Palacios Refrigerant circuit restrictions can be common things like a plugged filter drier or a restricted metering device. They can also be more difficult to diagnose and stem from exotic issues like a kinked liquid line, blocked evaporator feeder tube, or a compressor connected improperly with a discharge line full of solder […]

In many cases when a low-voltage or control circuit blows a fuse, it’s because one of the circuits is shorted to ground or common. That may happen because of rubbed-out wires, shorted components or boards, etc. Routing wires sensibly and using proper grommets to avoid rubouts and shorts will help prevent those problems. Less commonly, […]

Enthalpy is easy. It’s just a state function that depends only on the prevailing equilibrium state identified by the system’s internal energy, pressure, and volume. It is an extensive quantity. Simple. Like most things, the scientific definition is as clear as mud. In HVAC/R, we use enthalpy measurement to come up with the total heat […]

Electronic leak detection is a critical part of any HVAC technician’s common practice. Unfortunately, it is also one of the most common sources of misdiagnosis. Here are my tips to make your leak detection more successful: Use Your Senses First and Your Detector Second  Before starting to use your detector, STOP! Look for signs of […]