HVAC/R ELECTRICAL TRAINING
Basic Electrical for the Heating, Ventilation,
and Air Conditioning Technician
Electrical fundamentals, HVAC control components,
schematic reading and systematic troubleshooting.
This course introduces the electrical principles and control
components commonly encountered by heating, ventilation,
air conditioning and refrigeration technicians.
The lessons progress from basic electrical theory through
hands-on circuit construction, meter use, relays,
transformers and thermostats, and conclude by applying those
concepts to systematic electrical troubleshooting.
ABOUT THIS COURSE
Basic Electrical for the HVAC Technician
Written by Christopher Molnar.
This material was developed as introductory electrical
training for HVAC/R technicians and students. It combines
electrical theory with practical shop projects so that
electrical concepts can be applied to actual circuits.
How the Course Is Organized
The course alternates between learning electrical concepts
and applying those concepts in practical circuits.
LEARN
Understand the electrical principle, component or
schematic symbol.
BUILD
Apply the principle by constructing and examining
an electrical circuit.
MEASURE
Use a meter to determine what is actually happening
electrically.
TROUBLESHOOT
Compare expected circuit operation with actual
measurements to locate faults.
COURSE CONTENTS
Start the Course
Work through the sections in order if you are new to
electrical troubleshooting, or select an individual
lesson or shop project for review.
PART I
Electrical Fundamentals
Begin with the electrical principles needed to
understand every circuit that follows.
COURSE INTRODUCTION
Introduction
Learn what the course covers, the equipment used,
basic safety expectations and how the lessons and
shop projects work together.
Open Lesson →
ELECTRICAL THEORY
What Is Electricity?
Learn voltage, current, resistance, AC and DC,
line voltage, control voltage and the basic
electrical ideas used throughout the course.
Open Lesson →
SHOP PROJECT
Build a Circuit
Apply the electrical fundamentals by constructing
a basic operating circuit and identifying its
electrical components.
Open Shop Project →
ELECTRICAL THEORY
Ohm’s Law
Understand the relationship between voltage,
current and resistance and how a change in one
quantity affects the others.
Open Lesson →
PART II
Measuring and Understanding Circuits
Learn to use the meter and begin following
electrical operation through a circuit.
TEST EQUIPMENT
How to Use a Meter
Learn how to measure voltage, resistance and
current, recognize open and complete circuits,
and use a meter safely.
Open Lesson →
SHOP PROJECT
Trace the Circuit You Just Built
Use meter readings and test points to follow
voltage through the circuit constructed in the
earlier shop project.
Open Shop Project →
TROUBLESHOOTING FOUNDATION
Source, Switch, Path, and Load
Learn the four-part model used throughout the
remainder of the course to understand and
troubleshoot electrical circuits.
Open Lesson →
THE TROUBLESHOOTING MODEL USED THROUGHOUT THIS COURSE
Source → Switch → Path → Load
As circuits become more complicated, continue breaking
them into these four basic electrical functions.
Source
Where does the electrical energy originate?
Switch
What controls whether the circuit is complete?
Path
Is there a complete path through the circuit?
Load
What component uses the electrical energy?
PART III
Series and Parallel Circuits
Build and compare the two basic circuit
arrangements encountered in electrical systems.
SHOP PROJECT
Build a Series Circuit
Construct a series circuit and examine how
voltage, current and loads behave when components
share a single electrical path.
Open Shop Project →
SHOP PROJECT
Build a Parallel Circuit
Construct a parallel circuit and examine how
multiple loads operate across the same electrical
source.
Open Shop Project →
PART IV
HVAC Control Components
Apply the electrical fundamentals to relays,
transformers, low-voltage control circuits and
thermostats.
HVAC CONTROL COMPONENT
The Relay
Learn relay coils, normally open and normally
closed contacts, relay operation and the
relationship between control and load circuits.
Open Lesson →
SHOP PROJECT
Line Voltage Relay Shop Project
Build and troubleshoot a line-voltage relay
circuit using the pictorial and ladder diagrams,
relay contacts and designated test points.
Open Shop Project →
HVAC CONTROL COMPONENT
The Transformer
Learn transformer operation, primary and secondary
circuits, step-down voltage and why the transformer
secondary becomes the source for the low-voltage
circuit.
Open Lesson →
SHOP PROJECT
Build a Circuit with a Transformer
Apply transformer, relay and control-circuit
concepts by constructing and testing a low-voltage
control circuit.
Open Shop Project →
HVAC CONTROL COMPONENT
Thermostats
Learn heating and cooling thermostat action,
temperature-sensing methods, thermostat schematic
symbols and the thermostat’s role in a 24 VAC
control circuit.
Open Lesson →
PART V
Putting It All Together
Apply everything learned in the course to
systematic electrical troubleshooting.
REFERENCE
Course Reference Material
Use the appendix while reading schematics,
completing projects or troubleshooting circuits.