Electric Circuits 3
Chapter 05 Components, Symbols, and Circuitry of Air-Conditioning Wiring Diagrams 5
Reading Schematic Diagrams 6
Contactors, Relays, and Overloads 10
Thermostats, Pressure Switches chapter 11!
100
Circuits
This type of circuit has only one path for electron flow and is commonly used in control circuits.
What is a series circuit?
100
Identify these symbols
Condenser fan Motor, Red light ,crankcase Heater, heater, motor
100
Category: Diagram Basics
These diagrams are easiest to understand when technicians break them down circuit by circuit rather than looking at the whole page at once.
Answer: What are schematic diagrams?
100
These three parts must all operate correctly or a contactor will fail to make or break a power circuit.
Answer:
What are the coil, contacts, and mechanical linkage?
100
This thermostat uses a microprocessor AND is the most common thermostat in new residential systems.
What is a digital thermostat?
200
Parallel Power
This is the most common type of electric circuit in the HVAC industry because it allows full line voltage to be supplied to all loads.
What is a parallel circuit?
200
a. Open ( rises)
b. closed thermostats (cooling)
c. Pressure switch open
d. Pressure switch close
e. Double pole switch!
200
Category: Troubleshooting
According to the chapter, technicians should focus on this part of a system when diagnosing problems using schematics.
Answer: What is the circuit or load that is not operating properly?
200
5.
Unlike contactors, the contacts on this device are usually enclosed, making visual inspection impossible.
Answer:
What is a relay?
200
This thermostat can control two stages of heating or cooling AND improves comfort by using a set differential.
Answer:
What is a staging thermostat?
300
Category: Troubleshooting Logic
If a load in a piece of equipment receives the correct voltage but will not energize, this circuit type tells you to check for an open switch upstream in the control wiring.
What is a series control circuit?
300
Category: Control Devices
If a device is capable of operating a compressor, this is the term used for it, based on its ability to handle higher current loads.
Answer: What is a contactor?
300
Category: Essential Skill
No matter the type of control system, HVAC technicians must master this skill to troubleshoot systems effectively.
Answer: What is reading schematic diagrams?
300
This overload is mounted inside the motor windings and is wired in series with the motor’s common.
Answer:
What is an internal overload?
300
This thermostat type can communicate with system components AND can alert the homeowner remotely about system issues.
Answer:
What is a communicating thermostat?
400
Combination circuits
Most equipment control systems use this combination of circuits to supply voltage and control the system.
What is a series-parallel circuit?
400
Category: System Controls
These two HVAC switches perform similar functions but are distinguished by symbols showing whether they open or close under heating, cooling, low pressure, or high pressure conditions.
Answer: What are thermostats and pressure switches?
Answer: What are thermostats and pressure switches?
400
Category: Complexity
The number of these two things—not the voltage level—determines how simple or complicated a 120- or 240-volt appliance schematic becomes.
Answer: What are loads and switches?
Answer: What are loads and switches?
400
This device is similar to a contactor but includes built-in overload protection sized specifically for the load.
What is a magnetic starter?
400
This pressure switch protects a system from low suction pressure AND is also used to operate certain components when suction drops.
Answer:
What is a low-pressure switch (LPS)?
500
Electrical Relationships
In this type of circuit, voltage is the same across every component, and total current is the sum of each branch.
Answer: What is a parallel circuit?
500
Category: Diagrams
This type of diagram is most commonly used by technicians for troubleshooting because it shows wiring in circuit-by-circuit form and explains when and why the system operates.
Answer: What is a schematic diagram?
500
Category: Advanced Applications
Heat pumps and light commercial A/C units fall into this category due to their more detailed and complex schematics.
Answer: What are advanced systems?
500
These four control components form the core of automatic control in modern HVAC equipment.
What are contactors, relays, overloads, and magnetic starters?
500
This device uses induction to modify voltage AND must increase in VA rating as low-voltage loads increase.
Answer:
What is a transformer?