Understanding Basic Electrical Wiring and Components in HVAC Systems

HVAC Electrical Wiring & Components

HVAC systems control the climate in our homes and in commercial buildings. HVAC stands for Heating, Venting, and Air Conditioning. This is an introductory general overview of basic electrical components and electrical wiring for beginners to the HVAC unit world.

HVAC technicians install, maintain, and repair the electrical components and wiring of HVAC systems. In order to do this, HVAC technicians learn all of the electrical systems and components, how each electrical component works (the electrical functions and electrical features), and the sequence of operations in the HVAC system.

Is this thing on?

One of the first concepts to learn about electrical components is how electricity flows through the HVAC units. This is determined by electrical components called relays. Simplified, relays can be switched open or switched closed. When the relay is open, the relay is off and in a non-electrified state. When a relay is closed, the relay is on and power travels to the relay and proceeds to the intended parts.

Let it flow through you

What’s telling the relay to switch from open to closed? Or closed to open?
There are many things that can tell a relay to switch from open to closed. Voltage, temperature, and pressure are all common ways that relays use.

  • Voltage—for example, when the relay receives 24 volts, it will close and turn on, distributing power to the next part.
  • Temperature—for example, if too hot, the relay will open and stop power.
  • Pressure switch—for example, an amount of pressure turns the relay to closed and power is distributed to the next electric component.

Many of the parts of an HVAC unit are considered electrical components. We’ve mentioned the important work of relays. Here are some of the electrical units that can be considered to work similarly to and with relays and will be explained in detail during HVAC training—Compressors, Motors, and Capacitors.

When you start from the point of a relay, you can see that a circuit board can be considered an elaborate series of relays. Even more elaborate are the following working HVAC electric parts—Thermostats, Transformers, and Condenser Motors.


Get Wired

Connecting all of the electrical components together is the electric wiring. To keep track of wiring, HVAC technicians rely on circuit schematics or visual representations of wiring programs. There are three basic types of circuit schematics used in HVAC today. They are the Line Diagram, the Ladder Diagram, and the Installation Diagram. You can think of these circuit schematics as road maps. Instead of roads, there are wires that travel from electrical component to component. The wires connect the various electrical components, deliver power to loads that make up the system, and deliver power to the controls.

  • Line diagram—circuit schematic drawing that physically resembles the equipment of the electrical circuit.
  • Ladder Diagram—instead of focusing on how the circuit looks, focuses on how the circuit functions, set up like treads on a ladder.
  • Installation Diagram—focuses on where the terminal board connections are, usually only used by installation contractors.
Ohm’s Law

The German physicist Georg Ohm discovered Ohm’s Law, the law that was named after him, in 1827. Ohm’s Law is one of electric relationships. This discovery was the true beginning of electrical analysis. It is a great way for beginners to visualize the relationship between power (watts), current (amps), and voltage (volts).


By knowing two values, we can determine the third missing value.
P= I x V
I= P/V

Air conditioning Repair techniques

Once an HVAC technician knows the electrical components, the sequencing of operations of the unit, and wiring of the HVAC unit, they can attempt to repair the HVAC air conditioning. They can begin by using a meter to test for power at each of the relays to see if it is switching properly.

But before the pros are called, homeowners can try some DIY air conditioning repair techniques.

Five easy things a DIYer could do to repair air conditioning
Even before they begin to use their expertise, the HVAC tech (or any DIYer) can do the following if the air conditioning isn’t working:

1. Check the breaker for a tripped fuse.
2. Examine the thermostat. Is it turned on or off? What is the temperature setting? Does the thermostat need new batteries?
3. Change the filter regularly. Is it clogged and stopping the airflow?
4. Let the ice melt. If there is ice on the unit, it can’t work well. Switch the system to fan to let the ice melt, or turn the unit completely off and let the ice melt.
5. Clean your ducts and registers. Could your ducts be dirty enough to block air? Are registers clear and free, or accidentally closed?


Things are pretty cool at Summit College

Do you want to learn more about the world of HVAC? The HVAC program at Summit College is enrolling at all three locations in California—San Bernardino, El Cajon, and Santa Ana.

Summit College’s HVAC program will help prepare you to succeed in the industry as an HVAC technician. Summit College’s instructors are experienced HVAC professionals, each with a wealth of practical industry knowledge. Their wisdom, which goes beyond the pages of a textbook, is a point of pride for Summit’s programs.

During Summit College’s HVAC program, you will be immersed in the intricacies of this in-demand skilled trade. Summit’s well-rounded curriculum will give you a glimpse into the HVAC industry’s many specializations. Throughout the program, students will take courses covering relevant topics, such as:

  • HVAC System Design
  • Commercial Environmental Systems
  • Electrical Systems and Components
  • Commercial Refrigeration
  • And more!

You will leave Summit’s program with the knowledge and expertise to succeed in an entry-level HVAC technician job.

Summit College’s nine-month HVAC program is offered at all three campuses: San Bernardino, El Cajon, and Santa Ana. Classes are offered during the day and at night. The program’s length allows students to enter the field in a short amount of time. Summit’s program provides the valuable experience students need to land entry-level positions.

Discover the Summit Difference. Get started today at summitcollege.edu.