Hvac Ac101 Final Review

Front 1

A contactor works on the principle of?

Back 1

Electromagnetism

Front 2

When a contactors coil is energized, how much resistance should be measured between terminal L1 and terminal T1?

Back 2

0 ohms

Front 3

The LRA (lock rotor amps) of an electric motor is approximately (??) times the FLA (full load amps)?

Back 3

6 times

Front 4

A potential type relay is used in conjunction with a start capacitor. Where does the potential coil pick up its power?

Back 4

From the additional voltage generated in the start winding.

Front 5

Contactor contacts that are badly pitted can cause the motor to burn out. true or false?

Back 5

True

Front 6

A sure sign of contact failure is discoloration on the contact surfaces. True or false?

Back 6

False

Hint 6

Silver can tarnish causing discoloration, but does not effect the contacts.

Front 7

A control can be which of the following?

Back 7

All of the above

Hint 7

Electrical, Mechanical, Electrical and Mechanical.

Front 8

An example of a power consuming device would be a _______ while an example of a non power consuming device would be ________.

Back 8

Light bulb and single pole single throw switch.

Front 9

if an air conditioning system is turned on but none of the major components (compressor, condenser indoor fan) are operating, what is the first thing that a technician should check?

Back 9

The power being supplied to the system.

Front 10

if an air conditioning system is calling for cooling and the compressor is running but the indoor evaporator fan is not running, which terminal on the thermostat will the technician most likely check first?

Back 10

The green wire

Front 11

An electrical power consuming component:

Back 11

Uses power and is normally wired in parallel.

Front 12

The line side of a switch is the:

Back 12

Side the power is connected to.

Front 13

If a conductor carrying electrical current is formed into a coil, the magnetic field around the wire will:

Back 13

Increase

Front 14

if ten 60 watt light bulbs are wired in parallel with each other and are connected to a 120 volt power supply, what will a voltmeter read if connected across anyone bulb?

Back 14

120 volts

Front 15

When checking the amps the unit must be?

Back 15

Operating

Front 16

Three 10 ohm resistors are connected in a series circuit. The total resistance is?

Back 16

30 Ohms

Front 17

As additional loads are added to a parallel circuit the current will:

Back 17

Increase

Hint 17

Not decrease.

Front 18

A parallel circuit has three resistors of 20 ohms, 10 ohms and 25 ohms. What is the total resistance?

Back 18

5.26 Ohms.

Hint 18

Front 19

When you become a load you can:

Back 19

B and C = get severe Burns and suffer heart failure and die.

Front 20

All loads must have a minimum of two wires going to them. True or false?

Back 20

True

Front 21

In an air conditioning system, what device is used to interrupt source voltage?

Back 21

All the above

Hint 21

Breakers, disconnect switch, relay.

Front 22

When working on an air conditioning system what is the most important thing to remember?

Back 22

Safety

Front 23

in a circuit with two or more resistances in parallel, the total resistance in the circuit is the sum of the resistance in the circuit. True or false?

Back 23

False

Front 24

A permanent split capacitor (PSC) motor is running and up to speed will have the start winding:

Back 24

Energized

Hint 24

Opposite of de-energized

Front 25

A motor speed is determined by:

Back 25

The number of motor poles and frequency of power.

Front 26

The start windings have:

Back 26

More turns than the run windings

Front 27

Capacitors wired in series with the starting winding provide:

Back 27

Greater starting torque

Front 28

The shaded pole motor:

Back 28

Has little starting torque

Front 29

A permanent split capacitor motor (PSC) has a:

Back 29

Run capacitor only

Front 30

A centrifugal switch contacts are normally open. True or false?

Back 30

False

Front 31

Voltage is the force that moves the electrons. True or false?

Back 31

True

Front 32

What is the best method to repair a fractional horsepower motor that has bad bearings?

Back 32

Replace the entire motor

Front 33

a technician needs to check a single phase compressor. He labels the three terminals a, b, and c and takes resistance readings of the windings. He reads 10 ohms from a to b, infinity from b to c, and infinity from c to a. Identify the terminals.

Back 33

Can I identify terminals: open winding.

Front 34

If a motor hums but does not start, there is a potential problem.

Back 34

All the above

Front 35

An open winding in an electric motor means that:

Back 35

A wire in the winding is broken

Front 36

three terminals in the compressor junction box are marked 1, 2, and 3. Using an ohmmeter, the resistance of the internal motor windings are: 1.5 ohms between terminals 1 and 2; 3.5 ohms between terminals 1 and 3; and 5 ohms between terminals 2 and 3. The common terminal is?

Back 36

1

Front 37

What is another name for voltage?

Back 37

Potential

Front 38

As loads are added in a parallel circuit, the total resistance of the circuit will:

Back 38

Decrease

Front 39

If two light bulbs are wired in series and a bulb burns out, the other will:

Back 39

Go out

Front 40

What type of charge does an electron have?

Back 40

Negative

Front 41

What part of an atom moves from one atom to another?

Back 41

Electrons

Front 42

Typical insulators are?

Back 42

Glass, rubber, plastic.

Front 43

To find the watts of electrical power in an electrical circuit, you multiply:

Back 43

Volts and amperes

Front 44

An ampere is:

Back 44

Measurement for current.

Front 45

Several switches in a single electrical circuit are usually wired in:

Back 45

Series

Front 46

The compressor motor and condenser fan motor are wired in:

Back 46

Parallel

Front 47

If three bulbs are wired in parallel and one bulb burns out, the total current of the circuit will decrease. True or false?

Back 47

True

Front 48

when calculating the total resistance of a parallel circuit, the result will always be lower than the lowest resistance. True or false?

Back 48

True

Front 49

if a wire carrying electrical current is wrapped in a coil, the strength of the magnetic field generated by the wire will increase. True or false?

Back 49

True

Front 50

in a circuit that has two or more resistances in series the total resistance in the circuit is the sum of the resistance. True or false?

Back 50

True