Modern Refrigeration and Air Conditioning Exam Questions Answered Correctly Latest Update 2025
Power - Answers the rate at which work is performed. It is calculated by dividing the total amount of
work performed by the time during which the work was taking place.
HP to Watts - Answers 1hp = 550 ft-lbs/S = 746 watts = .75kw
1kw = 1000 watts = 1000j/S
= 1000 N•m/s = 1.33hp
1 ton of cooling - Answers 12,000 btu/hr
Accumulator - Answers A tank in the suction line that prevents liquid refrigerant from flowing through
the suction line and into the compressor.
Suction Line - Answers Is tubing that carries refrigerant vapor from evaporator to condenser. It should
slope from the evaporator down to the compressor.
Suction Insulation - Answers Insulation is placed over a copper suction line to prevent the formation of
condensation on the line and prevent reduced system efficiency from heat absorbed outside the
conditioned space.
ACR Tubing - Answers Is usually charged and sealed with gaseous nitrogen. This keeps the tubing clean
and dry until it is used.
Annealing - Answers Is a process in which a substance is heated to a specific temperature range and
allowed to cool slowly.
Work Hardened - Answers Soft ACR tubing can be hardened by oxidation or repeated bending and
hammering. Work hardened copper may crack at stress points when flared.
Stainless steel tubing - Answers Comes in typical tubing sizes for refrigeration. Stainless steel is strong
and very resistant to corrosion. It may be easily connected to fittings by flaring or brazing.
Vacuum Gauges - Answers Measures lower-than-atmospheric pressure. Atmospheric pressure is 24.7
psi, which can also expressed as 29.92 in.
Gauge Manifold - Answers Consists of a compound (low-side) gauge, a high-pressure (high side) gauge,
Recovered Refrigerant - Answers Is returned to the system from which it was taken following a repair of
the system.
Recycled Refrigerant - Answers Can be returned to the system it was recovered from or used in another
system belonging to the same owner.
Reclaiming Refrigerant - Answers Refers to reprocessing a recovered refrigerant so that it is chemically
pure.
, Refrigeration Purity - Answers According to EPA regulations, reclaimed refrigerant must meet the AHRI
Standard 700for purity.
Cylinder Capacity - Answers Earlier recovery cylinder standards states that the proper fill level of a
recovery cylinder was 80% of the water capacity. (WATER CAPACITY BY WEIGHT) is the newer standard.
Resistance - Answers Is the name of the electrical property that express how much the material resists
the flow of electrons through it. The electrical resistance of a material is measured in ohms.
Electrical Power - Answers When current flies due to a potential difference (emf or voltage), there is
electrical power. Electrical power is measured in watts (W),
Hermetic Compressor - Answers Consists of a motor sealed inside a compressor dome along with the
compressors mechanical parts. The motor and it's windings are exposed to the refrigerant and Oil inside
the compressor.
Voltmeter - Answers Connected in parallel are measuring the voltage of the input power (V1) the
voltage drop across a light (V2) and the voltage drop across a resistive heating element (V3)
Ammeter - Answers An in-line ammeter is connected in series with the circuit or load being measured.
Reciprocating Compressor - Answers Is a compressor that functions by changing the rotational
movement of a crankshaft into the reciprocating motion of the pistons within cylinders.
Oil Slugging - Answers Crankcase heaters are required on compressors that operate in ambient
temperatures lower than the evaporator temperatures. If refrigerant in the compressor is allowed to
condense, the refrigerant/oil mixtures in the compressor will begin to foam when the compressor starts.
This cause the oil charge to pump out of the compressor, a condition known as oil slugging.
Thermostatic Expansion Valve (TXV) - Answers Is operated by a pressure difference between the sensing
bulb pressure and low-side (evaporator) pressure.
If a therm expan valve is adjusted correctly, it will close whenever the compressor is idle.
TXV Design - Answers A typical thermostatic expansion valve assembly has a brass body into which the
liquid line and evaporator line are connected. The valve and seat are housed inside the the valve body.
The valve is joined to a flexible metal bellows or diaphragm. The valve is moved by a rod, connected at
the other end to a sealed bellows or diaphragm.
Superheat - Answers Refers to the difference in temperature between the evaporator inlet and the
evaporator outlet.
Increasing the superheat too much starves the evaporator.
Starving the evaporator means that liquid is only present in part of the evaporator.
Power - Answers the rate at which work is performed. It is calculated by dividing the total amount of
work performed by the time during which the work was taking place.
HP to Watts - Answers 1hp = 550 ft-lbs/S = 746 watts = .75kw
1kw = 1000 watts = 1000j/S
= 1000 N•m/s = 1.33hp
1 ton of cooling - Answers 12,000 btu/hr
Accumulator - Answers A tank in the suction line that prevents liquid refrigerant from flowing through
the suction line and into the compressor.
Suction Line - Answers Is tubing that carries refrigerant vapor from evaporator to condenser. It should
slope from the evaporator down to the compressor.
Suction Insulation - Answers Insulation is placed over a copper suction line to prevent the formation of
condensation on the line and prevent reduced system efficiency from heat absorbed outside the
conditioned space.
ACR Tubing - Answers Is usually charged and sealed with gaseous nitrogen. This keeps the tubing clean
and dry until it is used.
Annealing - Answers Is a process in which a substance is heated to a specific temperature range and
allowed to cool slowly.
Work Hardened - Answers Soft ACR tubing can be hardened by oxidation or repeated bending and
hammering. Work hardened copper may crack at stress points when flared.
Stainless steel tubing - Answers Comes in typical tubing sizes for refrigeration. Stainless steel is strong
and very resistant to corrosion. It may be easily connected to fittings by flaring or brazing.
Vacuum Gauges - Answers Measures lower-than-atmospheric pressure. Atmospheric pressure is 24.7
psi, which can also expressed as 29.92 in.
Gauge Manifold - Answers Consists of a compound (low-side) gauge, a high-pressure (high side) gauge,
Recovered Refrigerant - Answers Is returned to the system from which it was taken following a repair of
the system.
Recycled Refrigerant - Answers Can be returned to the system it was recovered from or used in another
system belonging to the same owner.
Reclaiming Refrigerant - Answers Refers to reprocessing a recovered refrigerant so that it is chemically
pure.
, Refrigeration Purity - Answers According to EPA regulations, reclaimed refrigerant must meet the AHRI
Standard 700for purity.
Cylinder Capacity - Answers Earlier recovery cylinder standards states that the proper fill level of a
recovery cylinder was 80% of the water capacity. (WATER CAPACITY BY WEIGHT) is the newer standard.
Resistance - Answers Is the name of the electrical property that express how much the material resists
the flow of electrons through it. The electrical resistance of a material is measured in ohms.
Electrical Power - Answers When current flies due to a potential difference (emf or voltage), there is
electrical power. Electrical power is measured in watts (W),
Hermetic Compressor - Answers Consists of a motor sealed inside a compressor dome along with the
compressors mechanical parts. The motor and it's windings are exposed to the refrigerant and Oil inside
the compressor.
Voltmeter - Answers Connected in parallel are measuring the voltage of the input power (V1) the
voltage drop across a light (V2) and the voltage drop across a resistive heating element (V3)
Ammeter - Answers An in-line ammeter is connected in series with the circuit or load being measured.
Reciprocating Compressor - Answers Is a compressor that functions by changing the rotational
movement of a crankshaft into the reciprocating motion of the pistons within cylinders.
Oil Slugging - Answers Crankcase heaters are required on compressors that operate in ambient
temperatures lower than the evaporator temperatures. If refrigerant in the compressor is allowed to
condense, the refrigerant/oil mixtures in the compressor will begin to foam when the compressor starts.
This cause the oil charge to pump out of the compressor, a condition known as oil slugging.
Thermostatic Expansion Valve (TXV) - Answers Is operated by a pressure difference between the sensing
bulb pressure and low-side (evaporator) pressure.
If a therm expan valve is adjusted correctly, it will close whenever the compressor is idle.
TXV Design - Answers A typical thermostatic expansion valve assembly has a brass body into which the
liquid line and evaporator line are connected. The valve and seat are housed inside the the valve body.
The valve is joined to a flexible metal bellows or diaphragm. The valve is moved by a rod, connected at
the other end to a sealed bellows or diaphragm.
Superheat - Answers Refers to the difference in temperature between the evaporator inlet and the
evaporator outlet.
Increasing the superheat too much starves the evaporator.
Starving the evaporator means that liquid is only present in part of the evaporator.
