1050B Progress test

Question 1

What are devices that convert electrical energy to another form of energy?

Answer 1

Loads

Question 2

What is the first test used when troubleshooting electrical problems?

Answer 2

Check the power supply

Question 3

True or False: When making voltage or resistance checks on a compressor, place your leads directly on the compressor terminals.

Answer 3

False

Question 4

What type of troubleshooting technique starts from the line or control voltage side of the circuit and works toward the load device?

Answer 4

Systematic or Logical troubleshooting

Question 5

Is a crankcase heater an inductive or resistive load?

Answer 5

Resistive

Question 6

Is a contactor coil an inductive or resistive load?

Answer 6

Inductive

Question 7

Is a compressor motor an inductive or resistive load?

Answer 7

Inductive

Question 8

Is an electric heater element an inductive or resistive load?

Answer 8

Resistive

Question 9

Is a transformer an inductive or resistive load?

Answer 9

Inductive

Question 10

Is a gas valve an inductive or resistive load?

Answer 10

Inductive

Question 11

True or False: When a voltmeter is placed across a load, it will read the applied voltage, regardless of whether the load is good or bad.

Answer 11

True

Question 12

When making a continuity measurement of a switch, a 0 ohm reading indicates the switch is open or closed?

Answer 12

Closed

Question 13

While taking resistance measurements on a hermetic compressor, you read 30,000 ohms from the compressor casing to the starting terminal. Is the compressor good or bad?

Answer 13

Bad (indicates a grounded winding)

Question 14

Contacts that are closed when the contactor or relay is energized are called normally what?

Answer 14

Normally open

Question 15

Name the three terminals on a single-phase compressor.

Answer 15

Common, Start, Run

Question 16

How to determine common, start, and run from resistance readings?

Answer 16

• Highest resistance = Start to Run
• Middle = Start to Common
• Lowest = Run to Common

Question 17

The correct way to discharge a capacitor, if necessary, is to use:

Answer 17

20,000-ohm 2-watt resistor

Question 18

What is not an advantage of low voltage control circuit?

Answer 18

Lower current (incorrect because current increases as voltage decreases for same power)

Question 19

Most important thing to know before troubleshooting?

Answer 19

Understand the system operation and schematic

Question 20

True or False: Bypassing or overriding a safety control is okay until a replacement is found.

Answer 20

False

Question 21

True or False: Before making resistance measurements, isolate the component by disconnecting at least one lead.

Answer 21

True

Question 22

When making a continuity measurement of a switch, an infinite reading indicates the switch is open or closed?

Answer 22

Open

Question 23

After checking 240V with ohm scale, meter stops working—what’s the problem?

Answer 23

You damaged the meter by applying voltage while set to resistance

Question 24

Contacts that open when the contactor or relay is energized are called normally ____?

Answer 24

Normally closed

Question 25

A schematic diagram always shows contacts in what state?

Answer 25

De-energized state

Question 26

Behind which terminal is the overload located in a hermetic compressor?

Answer 26

Common

Question 27

When checking for grounds, use a high or low ohm scale?

Answer 27

High ohm scale

Question 28

What is a thermistor?

Answer 28

Temperature-sensitive resistor ## Footnote Thermistors are used for motor protection and sensing temperature changes in HVAC systems.

Question 29

What are the two types of thermistors?

Answer 29

* NTC: Resistance decreases as temperature increases * PTC: Resistance increases as temperature increases

Question 30

What is the definition of a load in an electrical context?

Answer 30

Electrical devices that consume power to perform work

Question 31

What are the types of loads in HVAC?

Answer 31

* Resistive: Heating elements, crankcase heaters * Inductive: Motors (compressor, condenser, evaporator fans), transformers, solenoids * Capacitive: Start and run capacitors

Question 32

Why is identifying load types important?

Answer 32

Critical for troubleshooting

Question 33

What is an advantage of low voltage control circuits?

Answer 33

* Safety: Reduces shock risk * Efficiency: Smaller wiring, lighter components * Precision: Better thermostat control

Question 34

What is a solid state timer?

Answer 34

Electronic timers with no moving parts

Question 35

What are the uses of solid state timers?

Answer 35

* Defrost cycles * Delays * Motor start controls

Question 36

What are the advantages of solid state timers?

Answer 36

* Accuracy * Durability * Vibration resistance

Question 37

List the steps for troubleshooting electrical problems.

Answer 37

* Understand the schematic * Verify power supply * Use hopscotch troubleshooting * Measure voltages logically across the circuit * Check resistances if needed * Isolate and replace faulty component

Question 38

What should be measured to check voltage or resistance on a compressor?

Answer 38

* Rated voltage between terminals during operation * Resistance: R-C (Low), S-C (Medium), S-R (Highest) * Ground Test: Should read infinite ohms to casing

Question 39

Is bypassing or overriding safety control allowed?

Answer 39

Never allowed — compromises system protection and voids warranties

Question 40

What is hopscotch troubleshooting?

Answer 40

Method: Checking voltage at critical points to locate circuit faults

Question 41

What do sensors for electronic motor protection include?

Answer 41

* Thermistors: Detect overheating * Current Sensors: Detect overcurrent and prevent motor damage

Question 42

What are the steps for resistance measurements on components?

Answer 42

* De-energize circuit * Disconnect at least one wire * Compare resistance to specs

Question 43

What is the purpose of start assist on a motor?

Answer 43

Increase starting torque

Question 44

List devices used for start assist on a motor.

Answer 44

* Start capacitors * Potential relays * Hard start kits

Question 45

What happens with hard start kits?

Answer 45

Used on PSC motors to briefly add a start capacitor, turning them into PSCR motors for better startup

Question 46

What does a voltmeter read across a good load?

Answer 46

Reads near 0V

Question 47

What does a voltmeter read across a bad load?

Answer 47

Reads full source voltage

Question 48

What does 0 ohms indicate in switch measurements?

Answer 48

Switch is closed

Question 49

What does infinite ohms indicate in switch measurements?

Answer 49

Switch is open

Question 50

What are N/O and N/C contacts?

Answer 50

* N/O (Normally Open): Open when de-energized * N/C (Normally Closed): Closed when de-energized

Question 51

What is the behavior of varistors?

Answer 51

Resistance decreases with voltage rise

Question 52

What are common materials used to make semiconductors?

Answer 52

* Silicon (most common) * Germanium

Question 53

How are semiconductors doped?

Answer 53

* Boron (P-type) * Phosphorus (N-type)

Question 54

What are diodes and rectifiers used for?

Answer 54

* Diodes allow one-way current flow * Rectifiers convert AC to DC

Question 55

What are the parts of a transistor?

Answer 55

* Base * Collector * Emitter

Question 56

What are the types of transistors?

Answer 56

* NPN (negative) * PNP (positive)

Question 57

What is the purpose of transistors in HVAC control circuits?

Answer 57

Amplify signals, act as switches

Question 58

What do schematic diagrams show?

Answer 58

Always show components in their de-energized (normal) state

Question 59

What are the terminals on a single-phase compressor?

Answer 59

* C: Common * R: Run * S: Start

Question 60

What is the internal component behind the compressor terminal?

Answer 60

Overload Protector: Protects compressor from overheating

Question 61

How do you identify C, R, S windings?

Answer 61

* Highest Ohms: Start to Run * Middle: Start to Common * Lowest: Run to Common

Question 62

What should be used to check grounded loads?

Answer 62

Use high resistance scale

Question 63

What does infinite resistance indicate when checking grounded loads?

Answer 63

Good

Question 64

What does any reading indicate when checking grounded loads?

Answer 64

Ground fault

Question 65

What are the steps for troubleshooting a compressor service call?

Answer 65

* Check voltage * Inspect contactor * Check capacitors * Measure winding resistance * Test for grounded windings

Question 66

What are the steps for troubleshooting a thermostat service call?

Answer 66

* Confirm 24V control voltage * Verify thermostat output signals * Bypass with jumpers if needed * Replace faulty thermostat

Question 67

What are the steps for checking resistance?

Answer 67

* Power off * Disconnect one side of the component * Set meter to Ohms * Measure and compare to specifications

Question 68

What is a semiconductor?

Answer 68

Halfway between conductors and insulators

Question 69

What are LEDs used for?

Answer 69

Light-emitting diodes for indicators

Question 70

What is the purpose of triacs?

Answer 70

Switch AC current in both directions

Question 71

What is the acceptable voltage imbalance in three-phase systems?

Answer 71

Must be <2%

Question 72

What is a service tip when troubleshooting components?

Answer 72

Always verify proper voltage before troubleshooting components