Electrical Fundamentals & Troubleshooting

In a series circuit (loads connected in a row end to end), it's easy to calculate total circuit resistance because you simply add up all the resistances to get the total. In a parallel circuit, the voltage is the same across all the loads; the amperage is simply added up, but the resistance is a […]

Disclaimer: “Ghost voltage” is a term used by techs to explain a phenomenon where they measure voltage they don't expect or when the voltage they see doesn't do the work they expect. More advanced techs know how to use the Lo-Z (low impedance) mode on their voltmeter if it has one to help eliminate this. […]

Have you ever noticed that a blower motor rated for 120V draws about twice the amperage of the same horsepower motor rated at 240V? That is because motors are rated in watts or horsepower, and according to Watt's law, Watts = Volts x Amps. To keep the wattage output the same at 120V, it draws […]

HVAC work is never just “HVAC” work. One minute you're brazing copper, and the next you're troubleshooting a blown fuse in a disconnect or running a new whip to a condenser. Because our trade is so varied, you never know what you're going to find when you open a service panel or crawl into an […]

Some quick basics: An ohmmeter is used to measure the resistance to electrical flow between two points. The ohmmeter is most commonly used to check continuity. Continuity is not a “measurement” as much as it is a yes/no statement. To say there is continuity is to say that there is a good electrical path between […]

This HVAC system we recently installed has been causing quite a bit of trouble for us with inspectors. If you look at the label, you will see that the breaker size is 25 amps, and the minimum circuit ampacity (MCA or wire size) is 29 amps. The MOCP (maximum overcurrent protection, max fuse, or max […]

HVAC technicians typically focus on diagnosing issues related to mechanical wear, refrigerant leaks, or control problems within the equipment. However, damage can also originate from external sources. For instance, a failed control board might be attributed to internal shorts or rubouts. Yet, the root cause could be external, such as the voltage spike that can […]

As HVAC technicians, our responsibilities extend beyond the mechanical and refrigerant systems. The electrical power supply is an often-overlooked factor in equipment longevity. Protecting an HVAC system from damaging voltage fluctuations is a strategic step that reduces service calls and enhances the reliability of our installations. This guide will discuss the importance of voltage protection […]

I hear the following phrase a lot: It's the amperage that will kill you, not the voltage. While there is truth to the statement, it is sort of like saying, “It's the size of the vehicle, not the speed that kills you when it hits you.” OK, so that's a pretty bad example, but hopefully, […]