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CR-400 Unit 73 Flashcards | StudBud
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CR-400 Unit 73
CR-400 Unit 73
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Questions
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Answers
1
Refrigeration systems problems are classified into what?
Refrigerant Quantity and Flow Rate
Refrigerant Temperature
Refrigerant Flow Rate
Refrigerant Quantity
2
Why would the compressor run longer when system demand is not high?
Undercharged amount of refrigerant
Registers below normal operating pressures
Clogged with debris
Precharged with too much refrigerant
3
Why do heat pumps require a high amount of servicing?
They operate throughout the year
Clog frequently
Operate at intense speeds
Components are prone to corrosion
4
How can you determine the amount of airflow in a heat pump?
Measure the air temperature, amperage, voltage, and calculate the airflow
Align the thermometer with the heat strips and note the temperature
Align the thermometer with the heat strips and note the temperature
Compare the rate of airflow against external static pressure
5
What happens when the outdoor temperature starts dropping?
Less strain on compressor
Airflow increases
Compressor works harder
Airflow decreases
6
On the Reversing Valve, which line is the true suction?
Left line on the 3 line side
Middle line on the 3 line side
Single line by itself
Right line on the 3 line side
7
What methods are used to measure System Airflow?
Static Pressure and Emergency Heat Temperature Rise
Fan Speed
Emergency Heat Temperature Rise
Static Pressure
8
How can you reduce the chance of the check valves getting stuck?
Install backup check valves
Use a ball-style check valve
Use a flapper-style check valve
Lubricate the check valves
9
How does pressure-time-temperature defrost system measure frost?
Differential airflow pressure Switch
Timer control triggered by pressure drop
Timing Circuit that controls defrost thermostat
Reversing Valve that controls defrost thermostat
10
Why would a temperature-differential defrost system NOT complete the defrost cycle?
Too much heat available during defrost
Refrigerant undercharged
Fan blows warm air across the coil
System defrosts too frequently
11
What type of oil is required for Electric Motors?
Automotive oil
Detergent Free
No oil
Refrigerant oil
12
How often should you inspect the blower motor on a heat pump?
Every 2 years
Once a year
Every 6 months
Every 3 months
13
Which of the following is a step in checking the system's defrost cycle?
Clear the area around the outdoor coil
Turn off the pressure switch
Set the thermostat to a higher temperature
Short the test pins together
14
Why would the timer on a time-temperature defrost system reset?
Defrost temperature is not warm enough
Timing circuit starts a new countdown
Defrost temperature is not cold enough
System did not trigger the switch on the board
15
Why would you use supply registers with curved louvers?
System has higher airflow
Occupants feel less of a draft
Air disperses throughout the room
System operates more efficiently
16
How do you position a reversing valve when replacing it?
Main piston in a horizontal position
Main piston in a vertical postion
Level with the pilot valve
Higher than the pilot valve
17
Which of the following signifies a power supply issue?
Malfunctioning Thermostat
Temperature Drop
Inconsistent Water Flow
Inconsistent Airflow
18
Why must you cover the coils when testing the heat pump in warm weather?
Reduce the amount of heat lost from the system
To trigger the temperature valve to release excess pressure
To prevent the heat pump from overloading the compressor
Increase the amount of heat delivered to the system
19
Which of the following techniques releases a stuck check valve?
Switching the cycles to create or release pressure on the valve
Adding refrigerant to shift the position of the valve
Purging the system to shift the position of the valve
Moving a magnet along the middle or end of the valve
20
Service Problems on Heat Pumps fall into which categories?
Airflow, Electrical, and Refrigeration
Electrical and Defrost
Electrical, Airflow, Refrigeration, Defrost
Refrigeration and Airflow
21
If your temperature drop through the evaporator is higher than specified, what does this incinuate?
Outdoor temperature is higher
Airflow has decreased
Airflow has increased
Refrigerant pressures are higher
22
How do you check system performance during the heating cycle?
Recharge system using a heating performance check chart
Consult system pressure charts for indoor and outdoor temperatures
Attach a low pressure guage to the vapor line
Recharge system with correct amount of refrigerant
23
What is the first step in testing Air System Problems?
Measure refrigerant temperature in the Condenser
Measure refrigerant temperature in the Evaporator
Measure outdoor temperature
Measure temperature drop through the Evaporator
24
How can you force a defrost cycle?
Disconnect the thermistor
Jump the test pins
All of the above
Running heat mode without the outdoor fan
25
On the reversing valve, which line is the true discharge?
Right line on the 3 line side
Left line on the 3 line side
Middle line on the 3 line side
Single line by itself
