313D Exam Prep 1 (Complete) Flashcards
The two measurements required to find relative humidity in a room are?
Wet bulb and dry bulb temperature
The purpose of the potential relay is to?
Remove the capacitor after compressor start up
If a hermetic compressor is off due to an open internal overload, it can be reset by?
Disconnecting power, spraying water in the compressor
What type of oil should be used for the indoor blower motor?
10 grade motor oil
What must be considered when determining condensing unit placement?
Natural gas meter
If an addition is added to a home with an existing HRV, what must be done after the addition is completed?
Balance the HRV system airflow
A column of mercury is usually used to measure?
Atmospheric pressure
An ERV will recover?
Both sensible and latent heat
An HRV will recover?
Sensible heat only
When De-commissioning an air conditioning unit, the minimum standard in Ontario is to _______ the refrigerant.
Recover
Low airflow in air supply systems utilizing zone systems can be caused by?
Bypass damper in full open position
In a system with 2 supply air zones, we receive a service call indicating one zone is maintaining perfect temperature but the other zone has no cooling. The damper motors for both zones have a 24 V signal to the actuators, where would you check next?
Mechanical linkage
To determine proper evaporator airflow you could measure?
Temperature drop
The external equalizing line on a TXV is installed at?
The outlet of the evaporator downstream of the sensing bulb
Air velocity in a ductwork system can be measured using a?
Velometer
Voltage is measured using a(n)?
Multimeter
Amperage is measured using a(n)?
Ammeter
A flooded refrigerant condition in the evaporator could be caused by which setting?
Low superheat setting
Most manufacturers of air conditioning systems require a deep vacuum level of?
500 microns
To decrease the superheat setting on an evaporator that utilizes a TXV you would?
Decrease spring pressure on the valve
Evaporator pressure drop can be measured using?
Manometer
The amount of glycol concentration found in a ground source loop can be found using a?
Refractometer
If the condenser fan motor is drawing high amperage, which if the following could be to blame?
1. Overcharge of refrigerant
2. Low airflow through the condenser
3. Too much airflow through condenser
4. Undercharge if refrigerant
2.Low airflow through the condenser
The access port on the suction line filter drier is used for?
Measure pressure drop across the drier
Where must the suction line filter drier be installed?
Between the evaporator and the compressor
Where must the liquid line filter be installed?
Between the condenser and the metering device
To activate the indoor blower, what two terminals are utilized?
R and G
When replacing a drive (motor) pulley what are the most important factors to consider?
Belt width, motor RPM, alignment, shaft size
To test the operation of the high limit after a fan Center relay has been installed you should?
Turn fan switch to on position, disable the indoor blower, ensure gas valve closes on a call for heat
To test the low pressure switch installed on a condensing unit, you would?
Block airflow over the evaporator coil
To test a high pressure switch wired installed on a condensing unit, you would?
Block airflow over the condensing coil
On a mid efficient furnace with air conditioning installed, if four wires are used for low voltage wiring between the furnace and the thermostat, what must be done to ensure the system works properly?
Jump RH and RC terminals at the thermostat
Why is the air intake to an HRV insulated?
To prevent condensation from forming from the cold outside air
If the air inside a home with an electronic air cleaner installed on a 30 year old furnace has excess ozone, what should be done?
Wire the power supply to the EAC through a sail switch mounted in the ductwork (return)
If a 410A air conditioning system is being installed in a home and the new evaporator is unpackaged to discover that it is rated for R22, what should be done?
Replace the evaporator with 410A model
If an air conditioning system is being installed in a home and the new evaporator is unpackaged to discover that the end U tubes are crushed, what should be done?
Replace the evaporator with a new one
The heat absorbed in the evaporator must equal?
The heat removed from the air flowing over the evaporator
The unit rating plate for an R22 TXV system declares superheat of 10 degrees F, and also declares a subcooling of 10 degrees F. The system is running and has a suction pressure of 75 PSIG, and a suction line temp of 46 F, and a head pressure of 165 PSIG and a liquid line temp of 83 F. The indoor dry bulb is 75 F, and the wet bulb is 63 F. The outdoor dry bulb is 75 F and the wet bulb is 67 F. What is the first thing you should do?
Turn the TXV in
Volumetric efficiency increases when?
Head pressure decreases
What will happen if a metering device is too restrictive?
- Superheat will increase
- Suction pressure will decrease
- Subcooling will increase
- Head pressure will increase
If the heat loss calculation for a house was conducted assuming southern exposure, and the result was 19,000 BTU/HR, however when arriving to perform the installation you discover that the house is actually western exposure, you probably need?
1. 2 tons of cooling
2. 2.5 tons of cooling
3. 1.5 tons of cooling
4. 1 ton of cooling
3)1.5 tons of cooling
Potential relay contacts are open and closed by…
Counter EMF when the compressor starts and stops
What is likely to happen if an R22 liquid line rises 120 feet, and the pressure at the condenser outlet is 200 PSIG, and the liquid line ambient is 85 degrees F?
Poor operation of the TXV due to flash gas
What will be the approximate R22 liquid pressure at the metering device inlet if the liquid line rises 50 feet and the pressure at the condenser outlet is 200 PSIG (assume 100 degrees F)
Calculation is .56 (for 100 degrees F) X vertical height = N
Then take starting pressure and subtract N
* 0.56x50=28
* 200-28=172
172 PSIG
The factor for calculating pressure drop in PSI per foot of rising vertical liquid lines for R22 at 100 degrees F is?
0.56
The standard reversing valve…
- Is usually connected to the O and C terminals
- Needs at least 75 PSI to change position
- Needs the solenoid coil energized to operate in cooling mode
- Operating force is electromagnetism
- Driving force is system pressure
The heat pump in the defrost cycle is the cooling cycle…
With the outdoor fan turned off
When the air source heat pump is in heating mode, What must the evaporator temperature be?
Lower than the outdoor air
Residential ground source heat pumps chill the outdoor loop solution during which cycle?
Heating cycle
The operating force of the reversing valve is?
System pressure
An air conditioner with low condenser temperature rise indicates?
1. Evaporator airflow is blocked
2. Metering device is too restrictive
3. Unit is low on refrigerant charge
4. All of the above
4.All of the above
Which of the following statements is true?
1. Hot gas discharge lines have greater heat content than the suction or liquid lines
2. Liquid lines are cooler than suction lines
3. Liquid lines contain less heat content than suction lines
1.Hot gas discharge lines have greater heat content than the suction or liquid lines
&
3.Liquid lines contain less heat content than suction lines
Ture or False - An uninsulated suction line will cause liquid refrigerant to enter the compressor
False
An air conditioning system with a low evaporator load will?
1. Increases head pressure
2. Open the low pressure switch
3. Open the high pressure switch
4. Draws high compressor amperage
2.Open the low pressure switch
True or False - Power loss in the motor is converted to heat energy
True
The cooling anticipator is?
Non adjustable, energized during standby for cooling, and wired in parallel with the mercury bulb
Electromagnetism is used to operate?
- Relays
- Solenoids
- Motors
Motors briefly during start up will?
- Draw high amperage
- Cause a voltage drop
What size and type of breaker does a residential gas furnace typically use?
15 amp single pole breaker
True or False - Resistance converts electrical energy into heat energy
True
What is the correct method of checking high limit operation after a fan center is installed?
Disable the blower, set the thermostat to call for heat, set the fan switch to the on position
Which type of motor will have a start winding that is disconnected from the circuit after the motor has started?
Capacitor start induction run motor
Thermostats use …
Low voltage from the secondary side of the transformer to safely power high voltage loads
Electrons flow because?
- They repel each other
- Moving magnetic fields induce flow
- Attracted to protons
- Attracted to positive ions
Which alloy is commonly used to join copper to steal?
95% silver solder
Which of the following is a concern with 410A?
1. It increases ground level ozone (smog)
2. It operates at slight vacuum pressures
3. It is very toxic
4. None of the above
1.It increases ground level ozone (smog)
Suction lines should be slightly warmer than?
Slightly warmer than the evaporator saturation temperature
A properly operating reversing valve will have how many hot and/or cold pipes?
2 pipes that are hot, 2 pipes that are cold
Reversing valves have?
1. Two pipes connected to the compressor, one to the condenser, and one to the evaporator
2. One pipe connected to the compressor, one to the condenser, and two to the evaporator
3. On pipe connected to the compressor, two to the condenser, and one to the evaporator
4. None of the above
- Two pipes connected to the compressor, one to the condenser, and one to the evaporator
Heat pump high discharge pressure (in heat pump mode) can be cause by?
1. Frosted outdoor coil
2. Low humidity
3. Undersized ductwork
4. All of the above
3.Undersized ductwork
Low suction pressure can be caused by?
1. A clogged furnace blower
2. Loss of charge
3. Cold condenser ambient temperature
4. All of the above
4.All of the above
True or False - An A coil can contribute to furnace overheating
True
Liquid lines should be Slightly cooler than?
Slightly cooler than the condenser saturation temperature
On an R22 system, if the head pressure is 210 PSI, the condensing temperature would be?
105 degrees F
What does a Cooling anticipators do?
Both produce heat during the off cycle and shorten the off cycle
If the coil of a gas valve is shorted out, the heat anticipator will?
Burn out only if the thermostat is calling for heat
Safety devices are always connected in?
In series with the load being protected
When installing air conditioning on an older standard furnace the technician will need to?
- Check fan motor horse power and consider installing a larger pulley
- Check for a fan relay and install if one is not present
- Test all safety devices after altering any furnace wiring
The combination fan and limit control has?
- Normally open contacts on the fan side
- Is thermally driven
- Normally closed contacts on the limit side
The contacts of a potential relay are normally open or closed?
Normally closed
True or False - Motors convert electricity to strong, moving, magnetic fields
True
The contacts of an amperage relay are closed by the?
Run winding current
The sizes and lengths of liquid and suction lines are important because?
Both oil return and system efficiency/performance are affected
How should the technician determine that the recovery procedure is complete?
Achieve partial vacuum, close standoff valve, watch for minimal pressure rise
Proper use of a vacuum pump includes?
- Frequent changing of its oil
- Dehydrating s system
- Removing non condensables
Which of the following is a concern with 410A?
1. It is a global warming greenhouse gas
2. It depletes the stratospheric ozone
3. It depletes tropospheric ozone
4. None of the above
- It is a global warming greenhouse gas
What is the RPM of an 8 inch pulley if the 5 inch drive pulley is spinning at 1360 RPM?
- 5 / 8=0.625
- 0.625x1360=850RPM
850 RPM
HFC based refrigerants are responsible for?
Greenhouse gas emissions
True or False - Atmospheric air at 0 degrees F contains little heat
False
Temperature indicates?
The amount of sensible heat in a substance
If a single pole contactor on an air conditioning system with a trickle type crankcase heater is defective, and a double pole contactor is used to replace it, how should the technician wire the new contactor?
Both compressor wires to the load side of the contactor, and a jumper wire between the line and load terminals on one side of the contactor
The definition of refrigeration is?
The removal of heat from one area and transferring it to another area
Upon discovering a Refrigerant leak on an air conditioning system, the technician should?
Recover refrigerant, repair leak, pressure test with nitrogen, evacuate, add proper charge of refrigerant, record ODP documentation
What is not acceptable for pressure testing an air conditioning system with?
Oxygen
If heat is added to a liquid causing the temperature to rise, then the liquid is?
Not yet at it’s boiling point
A reversing valve with an internal leak will?
Both decrease compressor amperage and cause high suction pressure and low head pressure
When capacitors are connected in series, the resulting capacitance will…?
Be lower than the lowest capacitance of any of the individual capacitors
When capacitors are connected on parallel, the resulting capacitance…?
Is the sum of all the capacitors
Cadmium is?
- A substance found in batteries
- A highly toxic compound in silver solder
- Is found in some plated metals
When joining copper tubing, what tool should be used to expand the end of the tube to fit another tube inside of it?
Swedging tool
Burnt wires are an indication of?
- A poor connection or contacts
- Excessive amperage
- Undersized wiring
What system pressures would be typical of the following conditions?
Refrigerant: R22
Metering device: orifice
Outdoor temperature: 80 degrees F dry bulb
76 degrees F wet bulb
Indoor temperature: 75 degrees F dry bulb
65 degrees F wet bulb
75 PSI suction, 225 PSI head
If an R22 system has a suction pressure of 15 PSIG and a head pressure of 120 PSIG and the temperature of the suction line is 73 degrees F and there is a small amount of frost at the end of the cap tubes, what is the problem?
Major loss of refrigerant charge
A mechanically seized compressor will draw what kind of amperage?
Locked rotor amperage
Continuity testing will verify…
- Verify a shorted or open circuit
- Verify if a circuit is open or closed
- Verify a blow fuse
When electrical loads are connected in parallel, the total amperage is____ and the Voltage is ____?
The sum of all load amperage’s and the voltage is the same
When checking for resistance the meter used would be?
Ohmmeter
When checking current the meter used would be?
Ammeter
When checking for continuity the meter used would be?
Ohmmeter
Copper tubing glows cherry red in colour at what temperature?
1800 degrees F
When applying heat to a joint being brazed, what visually will indicate that the joint is hot enough to add filler alloy?
The copper will glow cherry red
Is it ever acceptable to install an evaporator in the return air duct of a furnace
Yes
Charging a system 410A…
1. With vapour is the proper way to introduce refrigerant into the system
2. With liquid could damage the compressor
3. With vapour will ruin the contents of the refrigerant cylinder
4. Both ruin contents and damage compressor
4.Both ruin contents and damage compressor
When will a properly operating reversing valve change positions?
Only change position on a call for cooling
Reversing valves are found on?
All heat pump systems
An equalizing line on an external equalizing TXV will connect the valves body to?
The evaporator outlet downstream of the sensing bulb
If the suction pressure is 72 PSIG and the suction temperature is 42 degrees F in an R22 system, is the compressor safe?
No, because liquid refrigerant could be entering the compressor
The definition of a BTU is?
The amount of heat required to raise 1 lb of water 1 degree F
How much refrigerant pressure is required to change the position of a reversing valve on a heat pump?
75 PSI
Which of the following is a concern with 410A?
1. Highly flammable
2. Operating pressures are much higher than R22
3. Highly toxic
4. All of the above
2.Operating pressures are much higher than R22
The first law of thermodynamics states?
Heat cannot be created nor destroyed
A reversing valve that has an internal leak will cause?
Compressor to overheat
The main reason for nitrogen sweeping while brazing is?
To remove oxygen from inside the tubing system
A reversing valve on a heat pump has how many inlets and outlets?
2 inlets and 2 outlets
A zone damper that fails to open can cause?
Can cause low suction pressure for a heat pump in cooling mode
If a technician finds a zone damper that is seized, what should be done?
Replace the damper motor, reactivate, and test the damper motor
Which of the following conditions could cause the evaporator to freeze up?
1. Too much airflow over the evaporator
2. Too much airflow over the condenser
3. Refrigerant overcharge
4. Open bypass humidifier damper
4.Open bypass humidifier damper
Which of the following conditions will cause head pressure to rise?
1. Metering device allowing too much refrigerant to pass through
2. Low condenser airflow
3. Low evaporator airflow
4. Low refrigerant charge
2.Low condenser airflow
If an air conditioner has a non bleed type TXV installed, which component should also be installed on the compressor?
Hard start kit
A magnahelic gauge can be used to determine?
Duct static pressure
Which device would help solve low suction pressure conditions?
Low ambient control
Which instrument is used to measure “wet bulb” temperature?
Psychrometer
Which instrument uses a “hot wire”?
Anemometer
Which instrument is used to measure inches water column?
Manometer
Fractionation is a concern when using which refrigerant?
R410A
Which gas is most dangerous to pressure test an air conditioning system with?
Oxygen
When fresh air is introduced to the home for ventilation purposes…
- It will increase humidity in the summer
- It will decrease humidity in the winter
- It must be filtered
- All of the above
4.All of the above
As the humidity in a conditioned space rises, the temperature difference across the evaporator will?
Decrease
What is the maximum distance an electrical disconnect switch can be mounted from a residential air conditioning condensing unit?
10’
If a heat pump outdoor section is completely iced over the probable problem is?
Defective defrost control
The wiring found in a residential breaker panel is?
240/120 volt, 1 phase, 60 Hz
Electromotive force is measured using?
A voltmeter
Fuses will blow if excessive ___________ Is present
Amperage
A reading of 0 volts is obtained across an energized fuse which means?
Fuse is good
Fuses are connected…
In series with the load being protected
Motor and compressor loads require which types of fuses?
Type D fuse (time delay)
Electricity is the flow of…
Valence electrons
A crankcase heater is used to…
Prevent the liquid refrigerant from migrating in the compressor
Which if the following refrigerants is a blend of different refrigerants?
1. R12
2. R410A
3. R717
4. R22
2.R410A
Proper amount of superheat indicates…
- Proper refrigerant charge,
- evaporator functioning properly
Proper amount of subcooling indicates…
- Proper refrigerant charge,
- condenser functioning properly
Superheat is found in…
The suction line
Evaporating substances will…
Absorb heat
Low suction pressure in an air conditioning system could be cause by?
1. A link in the liquid or suction line
2. Undersized ductwork
3. A metering device that is too restrictive
4. All of the above
4.All of the above
Heat anticipators are installed in…
Series with the gas valve
The technician must replace a 40 MFD, 440 volt capacitor, which of the following choices would be suitable in this application?
1. 58 MFD, 440 volt capacitor
2. 45 MFD, 440 volt capacitor
3. 40 MFD, 370 volt capacitor
4. 38 MFD, 440 volt capacitor
4) 38 MFD, 440 volt capacitor
A 35 MFD, 440 volt capacitor is faulty in a residential air conditioning unit. The technician could replace the capacitor with which of the following choices placed in parallel with each other?
1.20 MFD, 440 volt capacitor, 15 MFD, 370 volt capacitor
2.20 MFD, 440 volt capacitor, 12.5 MFD, 570 volt capacitor
3.20 MFD, 440 volt capacitor, 20 MFD, 370 volt capacitor
4.20 MFD, 440 volt capacitor, 15 MFD, 570 volt capacitor
2) 20 MFD, 440 volt capacitor, 12.5 MFD, 570 volt capacitor
Enthalpy is defined as…
The total amount of heat removed to change a substance (latent and sensible heat loads)
Latent heat is defined as…
A change of state of a substance without a change of temperature
Sensible heat is defined as…
A change of temperature of a substance without a change in state
The amount of latent heat required to change 1 lb of water to 1 lb of steam is?
970 BTU
Condensing refrigerant…
1. Requires latent heat of vapourization to occur
2. Changes state, not temperature
3. Absorbs heat
4. Changes temperature, not state
2.Changes state, not temperature
If a 5 mfd capacitor and a 15 mfd capacitor are placed in parallel with each other, the resulting capacitance will be?
4)20 mfd
If the water regulating valve on a water cooled condenser is restricted, the head pressure will?
Increase
If an A coil is found with one half frosting, and the other half of the evaporator condensating, what is the probable problem?
The unit is undercharged
What condition could cause liquid refrigerant to load up in the condenser?
1. Low refrigerant charge
2. Metering device orifice too restrictive
3. Low airflow across the evaporator
4. Cold outdoor ambient temperature
2.Metering device orifice too restrictive
The opening force on a TX valve is provided by?
The sensing bulb pressure
The closing force on a TX valve is provided by?
- The evaporator pressure
- Spring
Heating and cooling thermostats react to What type of heat?
Sensible heat only
Which of the following best describes “re-use”?
1. Take refrigerant out of the air conditioning unit, and place it in an approved container.
2. Take refrigerant out of the air conditioning unit, and place it in an approved container, and return the refrigerant to the system once repaired.
3. Take refrigerant out of the air conditioning unit, and place it in an approved container, send refrigerant off-site for oil separation and distillation process, and refrigerant is sold back to the industry as new refrigerant.
4. Take refrigerant out of the air conditioning unit, and place it in an approved container, put refrigerant through on site oil separation and distillation process, and return the refrigerant to the system once repaired.
2.Take refrigerant out of the air conditioning unit, and place it in an approved container, and return the refrigerant to the system once repaired
Which method of charging should be used when working on an air conditioning system utilizing a fixed orifice?
Superheat method
Which method of charging should be used when working on an air conditioning system utilizing a TX Valve?
Sub-cool method
Which of the following terms best describes “reclaim”?
1. Take refrigerant out of the air conditioning unit, and place it in an approved container, and return the refrigerant to the system once repaired.
2. Take refrigerant out of the air conditioning unit, and place it in an approved container.
3. Take refrigerant out of the air conditioning unit, and place it in an approved container, put refrigerant through on site oil separation and distillation process, and return the refrigerant to the system once repaired.
4. Take refrigerant out of the air conditioning unit, and place it in an approved container, send refrigerant off-site for oil separation and distillation process, and refrigerant is sold back to the industry as new refrigerant.
4.Take refrigerant out of the air conditioning unit, and place it in an approved container, send refrigerant off-site for oil separation and distillation process, and refrigerant is sold back to the industry as new refrigerant.
CFC refrigerants will not be available after?
CFC refrigerants are already banned
HCFC refrigerants will not be available after?
January 1, 2030
Which of the following terms best describes “recycle”?
1. Take refrigerant out of the air conditioning unit, and place it in an approved container, and return the refrigerant to the system once repaired
2. Take refrigerant out of the air conditioning unit, and place it in an approved container, put refrigerant through on site oil separation and distillation process, and return the refrigerant to the system once repaired
3. Take refrigerant out of the air conditioning unit, and place it in an approved container, send refrigerant off-site for oil separation and distillation process, and refrigerant is sold back to the industry as new refrigerant
4. Take refrigerant out of the air conditioning unit, and place it in an approved container
2.Take refrigerant out of the air conditioning unit, and place it in an approved container, put refrigerant through on site oil separation and distillation process, and return the refrigerant to the system once repaired
Which of the following best describes “recover”?
1. Take refrigerant out of the air conditioning unit, and place it in an approved container, send refrigerant off-site for oil separation and distillation process, and refrigerant is sold back to the industry as new refrigerant
2. Take refrigerant out of the air conditioning unit, and place it in an approved container, put refrigerant through on site oil separation and distillation process, and return the refrigerant to the system once repaired
3. Take refrigerant out of the air conditioning unit, and place it in an approved container
4. Take refrigerant out of the air conditioning unit, and place it in an approved container, and return the refrigerant to the system once repaired
3.Take refrigerant out of the air conditioning unit, and place it in an approved container
The Y terminal on the board of the furnace is used to?
Enable the outdoor condensing unit
The R terminal on the board of the furnace is used to?
Provide power to the thermostat
The W terminal on the board of the furnace is used to?
Enable the gas valve
The G terminal on the board of the furnace is used to?
Enable the indoor blower
The term FLA stands for?
Full load amperage
One Ton of refrigeration is equal to?
12,000 BTU
A GFCI receptacle protects against?
Amperage to ground
A residential air conditioning system utilizes which type of breaker?
Two pole breaker
Electrons….
1. Repel protons
2. Attract protons
3. Are neutral charged
4. Are positively charged
2.Attract protons
Nitrogen is?
Inert
What is the deepest reading in a vacuum?
3) 3500 microns
The flow temperature of silfos is?
1300 degrees F
The melting point of copper is?
1981 degrees F
The pressure found in an oxygen cylinder is?
2200 PSI
The pressure found in an acetylene cylinder is approximately?
250 PSI
The pressure found in a Carbon Dioxide cylinder is approximately?
800 PSI
The pressure found in a nitrogen cylinder is approximately?
2350 PSI
On an air conditioning system installation requiring additional refrigerant, the most accurate method of charging is?
Weighing charge into system
Which agreement deals with limiting greenhouse gas emissions?
Kyoto protocol
Which refrigerant will not cause ozone depletion but still contributed to global warming?
R410A
Subcooling is a term used to describe?
The heat removed from a substance below its boiling point
Superheat is a term used to describe?
The heat added to a substance after vapourizarion
What is the maximum fill level for a recovery refrigerant bottle at 70 degrees F?
80%
Increasing the pressure on a substance will _______ It’s boiling point?
Increase
A condenser in the air conditioning system is larger in size than the evaporator because?
The condenser must reject the heat of compression and sensible heat from the evaporator
On a capacitor start induction run compressor the capacitor is?
Removed from the circuit after starting
On a permanent split capacitor type of compressor the capacitor is?
In series with the start winding
On a combination limit control, the three tabs represent (looking from left to right on the control)?
1. Fan off, fan on, high limit
2. Fan on, high limit, fan off
3. Fan off, fan on, inducer on
4. Fan on, fan off, high limit
- Fan off, fan on, high limit
Relays are not available as?
1. Double throw models
2. Single throw models
3. Double pole models
4. Triple throw models
4.Triple throw models
If an air conditioning system is not functioning, and you are called to service the equipment, the following parameters are found:
* Compressor not operating
* Condenser fan not operating
* 24 volts found across contactor coil
* 240 volts found on the line side of the contactor
* 0 volts found across contactor contacts
* 1.2 ohm reading across condenser fan motor windings
* 1.5 ohm reading across compressor R and C windings, 3 ohm reading across compressor S and C windings, and 4.5 ohm reading across S and R compressor windings
* Compressor capacitor reads OL (35 rating)
* Condenser fan capacitor reads 4.8 microfarads (5 rating)
The problem is?
1. The condenser fan motor winding has gone to ground
2. The contactor is defective
3. A compressor winding is open
4. The compressor capacitor is defective
4.The compressor capacitor is defective
If an air conditioning system is not functioning, and you are called to service the equipment, the following parameters are found:
- Compressor not operating
- Condenser fan not operating
- 24 volts found across contactor coil
- 240 volts found on the line side of the contactor
- 0 volts found across contactor contacts
- 1.2 ohm reading across condenser fan motor windings
- Infinite ohm reading across compressor R and C windings, infinite ohm reading across compressor S and C windings, and 4.5 ohm reading across S and R compressor windings
- Compressor capacitor reads 33 microfarads (35 rating)
- Condenser fan capacitor reads 4.8 microfarads (5 rating)
The problem is?
1. A compressor winding is open
2. The compressor has thermal overload open
3. The compressor capacitor is defective
4. The condenser fan motor winding has gone to ground
2.The compressor has thermal overload open
If an air conditioning system is not functioning, and you are called to service the equipment, the following parameters are found:
- Compressor not operating
- Condenser fan not operating
- 24 volts found across contactor coil
- 240 volts found on the line side of the contactor
- 120 volts found across contactor contacts
- 1.2 ohm reading across condenser fan motor windings
- 1.5 ohm reading across compressor R and C windings, 3 ohm reading across compressor S and C windings, and 4.5 ohm reading across S and R compressor windings
- Compressor capacitor reads 33 microfarads (35 rating)
- Condenser fan capacitor reads 4.8 microfarads (5 rating)
The problem is?
1. The compressor capacitor is defective
2. A compressor winding is open
3. The contactor is defective
4. The condenser fan motor winding has gone to ground
3.The contactor is defective
A transformer with a 120 volt primary winding and a 24 volt secondary winding is?
A step down transformer
The minimum CFM required across an evaporator in an air conditioning system (per ton of cooling) is?
350 CFM
Cooling anticipators are resisters in the thermostat that?
Provide a false heat load in the off cycle of the air conditioning system
The contacts on a potential relay are?
Normally closed
The electrical supply to residential gas furnaces is?
120 volt, 1 phase, 60 Hz
The term LRA stands for?
Locked rotor amperage
When the lineset of an installed air conditioning system is longer than 50 feet in length the technician should?
Refer to the installation instructions
CFC based refrigerants break down in the upper atmosphere due to?
UV light from the sun
When checking continuity on an electrical circuit, the most important rule is?
Disconnect the power supply to the air conditioning system
HFC refrigerants do not contain?
Chlorine
Which refrigerant listed will not deplete the ozone layer?
1. R22
2. R502
3. R12
4. R410A
4.R410A
A clogged furnace air filter will cause?
1. A high liquid pressure in the condenser
2. A mixture of liquid and vaporized refrigerant
3. Low suction line pressure
4. Liquid low pressure refrigerant to enter the condenser
3.Low suction line pressure
The vacuum pump is used to?
Remove oxygen and moisture from the air conditioning system
The preferred substance used for air conditioning pressure testing is?
Nitrogen
Capacitors used in air conditioning systems are measured in?
Microfarads
The capacitor on a capacitor start induction run compressor is?
In series with the start winding
The type of soft drawn copper used in air conditioning is?
Type L
The most common type of compressor found in residential air conditioning is?
The permanent split capacitor
If a new air conditioning system is installed with a 45 foot lineset, and the unit is precharged with refrigerant for 15 feet, and the installation instructions indicate to add .6 oz per additional foot, to correctly charge the equipment the technician would?
- 45-15=30
- 0.6x30=18oz
Add 18 oz of refrigerant
A heat pump with a reversing valve that is leaking internally will cause?
High suction pressure and low discharge pressure
What would be the resistance across point C in the attached diagram?
OL (infinity ohms)
What would be the resistance across point B in the attached diagram?
A measurable resistance
What would be the resistance across point A in the attached diagram?
OL (infinity ohms)
On the diagram in the attached image, the refrigerant should be in what state at point D?
1. High pressure, low temperature, liquid
2. Low pressure, high temperature, vapour
3. Low pressure, low temperature, liquid
4. High pressure, high temperature, vapour
3.Low pressure, low temperature, liquid
On the diagram in the attached image, the refrigerant should be in what state at point B?
1. Low pressure, high temperature, vapour
2. Low pressure, low temperature, liquid
3. High pressure, high temperature, vapour
4. High pressure, low temperature, liquid
3.High pressure, high temperature, vapour
On the diagram in the attached image, the refrigerant should be in what state at point C?
1. Low pressure, low temperature, liquid
2. High pressure, high temperature, vapour
3. High pressure, low temperature, liquid
4. Low pressure, high temperature, vapour
3.High pressure, low temperature, liquid
On the diagram attached, the refrigerant should be in what state at point A?
1. Low pressure, high temperature, vapour
2. High pressure, low temperature, liquid
3. High pressure, high temperature, vapour
4. Low pressure, low temperature, liquid
- Low pressure, high temperature, vapour
