Heat Pumps, Ductless & Inverter Systems

Let's talk about the magic that is inverters and how to test the boards that drive this technology. Inverters play an extremely important role in household appliances, industrial machinery, and the rising popularity of household HVAC systems. Inverters consist of a wide variety of electronic circuitry, and there are many situations in which they need […]

As an A/C tech, I can sometimes get the terms “defrost termination” and “defrost fail-safe” mixed up because they sound pretty similar. Before we cover these terms, let's set the basic defrost groundwork for refrigeration (coolers and freezers). Defrost is accomplished in one of a few ways; these first two only apply to “coolers” where […]

This article includes significant contributions from Neil Comparetto and Brian Chadwick, both of whom are HVAC technicians in Virginia. Brian is also the owner of Chadwick Air, and Neil is a co-owner of Comparetto Comfort Solutions and a longtime contributor to HVAC School. Thanks, guys! DISCLAIMER: A lot of the information in this article is […]

Why Defrost? Let's start with the basics and move on from there. Defrost is necessary when the coil temperature drops below 32°F. Defrost can be as simple as turning the compressor off for a period of time or as elaborate as reversing the flow of refrigerant for the whole system or just parts of the […]

If you don’t have a gas furnace or fireplace in your home, your unit’s reversing valve is probably your best friend during the winter months.  As their name suggests, reversing valves reverse the refrigerant flow to send the hot, compressed vapor to the indoor coil instead of the outdoor coil. The system releases heat into […]

This article was written by Ryan Findley. Thanks, Ryan! This article will be geared toward HVAC techs who are new to mini-splits. As the mini-split market continues to grow, technicians face more and more challenges with these systems. The most critical challenges would be insufficient training and the lack of proper tools to work on […]

When you ask many people nowadays how to check the charge on a heat pump during low outdoor temps, they will say that you need to “weigh in and weigh out” the charge. While this may be an effective method, it isn't always practical. Now, if you are making a refrigerant circuit repair, weighing out […]

When you work on a heat pump system and want to test defrost, you can follow many different test procedures to test the board and sensors. Most involve “forcing” a defrost by shorting out pins on the board or advancing the time of the defrost initiation and installing a factory-provided pin jumper. Lots of pins […]

The most common method to defrost appropriately in refrigeration involves both time for initiation and a combination of time and temperature for defrost termination (ending defrost). But why can't we just use temperature or time alone? (You may wonder.) Imagine a common freezer with a designed box temperature of -10°F and a coil temperature of […]