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AZ HVAC practice questions

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Question 1Arizona Statutes, Rules, and Contractor Licensing Requirements

Under Arizona law, a contractor's license is generally required before a person may contract for construction work when the total cost of the project, including labor and materials, is at least:

  1. $500
  2. $2,500
  3. $1,000 Correct answer.
  4. $10,000

Explanation

Arizona's contractor licensing statute excludes from the definition of 'contractor' a person who performs work where the total project cost is less than $1,000, counting both labor and materials. Once the project reaches that threshold, a license is required.

Question 2Arizona Statutes, Rules, and Contractor Licensing Requirements

Which Arizona entity issues contractor licenses and investigates complaints against contractors?

  1. Arizona State Board of Technical Registration
  2. Registrar of Contractors Correct answer.
  3. Arizona Department of Housing
  4. Arizona Corporation Commission

Explanation

The Registrar of Contractors administers contractor licensing and complaint investigation under Arizona's contractor licensing statutes. The Board of Technical Registration regulates architects, engineers and similar design professionals, not contractors.

Question 3Arizona Statutes, Rules, and Contractor Licensing Requirements

Which Arizona contractor classification authorizes a licensee to perform air conditioning and refrigeration work on residential property?

  1. C-39
  2. R-39 Correct answer.
  3. B-1
  4. A

Explanation

Arizona uses an 'R' prefix for residential specialty classifications and a 'C' prefix for commercial specialty classifications. Air conditioning and refrigeration is specialty 39, so residential HVAC work falls under R-39.

Question 4Arizona Statutes, Rules, and Contractor Licensing Requirements

An Arizona licensee may perform construction work only:

  1. anywhere in the state if the work is done by the licensee's own employees
  2. within the classifications and scope of work shown on the license Correct answer.
  3. after notifying the Registrar of Contractors in writing of the new work type
  4. on projects valued below the dollar limit printed on the license certificate

Explanation

A license authorizes work only within the classification or classifications, and any scope limits, shown on the license. Contracting outside that scope is treated as unlicensed activity and is a ground for discipline.

Question 5Arizona Statutes, Rules, and Contractor Licensing Requirements

An Arizona contractor's license is:

  1. not transferable to another person or entity Correct answer.
  2. transferable to a buyer of the contracting business
  3. transferable to a spouse on written request
  4. transferable to a new owner with approval of the Registrar

Explanation

A contractor license is personal to the licensee and may not be sold, assigned, or transferred to another person or business. A successor business must qualify for and obtain its own license.

Question 6Arizona Statutes, Rules, and Contractor Licensing Requirements

Which individual may serve as the qualifying party for an Arizona contractor's license?

  1. A person who passes the exam and meets the experience requirements Correct answer.
  2. A licensed architect retained by the company on a consulting basis
  3. Any employee who holds a current EPA refrigerant handling certificate
  4. Any officer or director of the company, regardless of trade background

Explanation

The qualifying party must be an individual who passes the required licensing examination, documents the required trade experience, and is regularly engaged in the management of the contracting business. An unrelated credential, such as an architect license or an EPA certificate, does not satisfy these requirements.

Question 7Arizona Statutes, Rules, and Contractor Licensing Requirements

How much documented trade experience does an Arizona license applicant generally need in the classification being applied for?

  1. Three years
  2. Four years Correct answer.
  3. Two years
  4. One year

Explanation

Arizona requires roughly four years of journeyman-level experience in the trade applied for, although approved education or apprenticeship training may substitute for part of that time. The experience must be documented for the Registrar to review.

Question 8Arizona Statutes, Rules, and Contractor Licensing Requirements

An unlicensed individual completes an $8,000 remodeling job and the homeowner refuses to pay. In a court action to collect the contract price, the court will generally:

  1. award the contract price because the work was fully completed
  2. award the contract price less a 20 percent statutory penalty
  3. refer the payment dispute to the Registrar of Contractors for collection
  4. deny recovery because the work was performed without a required license Correct answer.

Explanation

Arizona law bars a contractor from bringing an action to collect compensation for work performed without a required license. The homeowner may still file a complaint against the unlicensed contractor with the Registrar of Contractors.

Question 9Arizona Statutes, Rules, and Contractor Licensing Requirements

What is the maximum amount that may be paid from the Residential Contractors' Recovery Fund on a single residential contract?

  1. $10,000
  2. $30,000 Correct answer.
  3. $50,000
  4. $20,000

Explanation

The Recovery Fund compensates owners harmed by licensed residential contractors who fail to perform or who violate the licensing statutes, up to $30,000 per residential contract. Additional limits apply to the total paid per licensee.

Question 10Arizona Statutes, Rules, and Contractor Licensing Requirements

The primary purpose of the Residential Contractors' Recovery Fund is to:

  1. pay suppliers and subcontractors who were not paid on a residential project
  2. fund the day-to-day operating budget of the Registrar of Contractors
  3. pay the legal defense costs of contractors named in ROC complaints
  4. reimburse homeowners harmed by the acts of a licensed residential contractor Correct answer.

Explanation

The fund is a consumer protection mechanism supported by license fees; it pays owners who obtain a judgment or order against a licensed residential contractor for work not performed or performed improperly. It does not cover contractor defense costs or ordinary commercial debts owed to suppliers.

Question 11Arizona Statutes, Rules, and Contractor Licensing Requirements

Arizona requires that a contractor's license number appear in:

  1. only invoices sent to commercial clients
  2. all advertising and marketing by the contractor Correct answer.
  3. only applications for building permits
  4. only contracts exceeding $10,000 in value

Explanation

Arizona requires a licensed contractor to include its license number in all advertising, including print, online and vehicle advertising, so consumers can verify the license. Failure to do so is a licensing violation.

Question 12Arizona Statutes, Rules, and Contractor Licensing Requirements

For a residential project, Arizona limits the deposit a contractor may collect in advance to:

  1. any amount the parties agree to in writing
  2. the cost of materials plus 10 percent
  3. one-third of the total contract price Correct answer.
  4. one-half of the total contract price

Explanation

Arizona rules cap advance deposits on residential work at one-third of the total contract price, protecting homeowners from large up-front payments. Collecting more than that exposes the contractor to discipline.

Question 13Arizona Statutes, Rules, and Contractor Licensing Requirements

The Registrar of Contractors is:

  1. appointed by the Governor Correct answer.
  2. elected by licensed contractors statewide
  3. selected by the state legislature
  4. chosen by the agency's advisory board

Explanation

The Registrar of Contractors is a gubernatorial appointee who heads the agency that administers contractor licensing and enforcement. The Registrar is not an elected office and is not chosen by the legislature or an advisory board.

Question 14Arizona Statutes, Rules, and Contractor Licensing Requirements

A licensed contractor subcontracts part of a job to an unlicensed individual. Under Arizona law, this is:

  1. a ground for disciplinary action against the licensed contractor Correct answer.
  2. permitted if the subcontract is under $1,000
  3. permitted because the licensed contractor remains responsible for the work
  4. permitted if the homeowner consents in writing

Explanation

A licensee may not aid or abet unlicensed contracting, and hiring an unlicensed subcontractor is a violation that subjects the licensee to discipline. The licensee's overall responsibility for the project does not cure the subcontractor's unlicensed status.

Question 15Arizona Statutes, Rules, and Contractor Licensing Requirements

The qualifying party for a licensed HVAC company resigns. What is required of the licensee?

  1. Notify the Registrar and replace the qualifier within the allowed period Correct answer.
  2. Convert the license to an inactive status and stop all advertising
  3. Transfer the license to the departing qualifying party
  4. Continue operating for the remainder of the license term without action

Explanation

A license depends on having a qualifying party who is regularly engaged in the business. When the qualifier leaves, the licensee must notify the Registrar and obtain a replacement within the time allowed, or the license may be suspended.

Question 16Arizona Statutes, Rules, and Contractor Licensing Requirements

When investigating a residential workmanship complaint, the Registrar of Contractors evaluates the work against:

  1. the contractor's own written warranty terms
  2. the equipment manufacturer's installation instructions
  3. workmanship standards adopted by the Registrar Correct answer.
  4. the opinion of the local building official

Explanation

The Registrar adopts written workmanship standards for residential construction and uses them to decide whether work was performed in a workmanlike manner. A failure to meet those standards is a ground for disciplinary action.

Question 17Arizona Statutes, Rules, and Contractor Licensing Requirements

Who may file a complaint against a licensed Arizona contractor with the Registrar of Contractors?

  1. Only the property owner who signed the contract
  2. Only a building official with jurisdiction over the project
  3. Any person, including a homeowner, tenant, or another contractor Correct answer.
  4. Only a person who has already obtained a court judgment

Explanation

The complaint process is open to any person who believes a contractor has violated the licensing statutes, regardless of whether that person signed the contract. A prior court judgment is not a prerequisite to filing.

Question 18Arizona Statutes, Rules, and Contractor Licensing Requirements

The Registrar determines that an unlicensed person is advertising and performing work that requires a license. The Registrar may:

  1. issue a cease and desist order against the person Correct answer.
  2. impose criminal fines without any court proceeding
  3. take no action until a property owner files a complaint
  4. revoke a license that the person does not hold

Explanation

The Registrar has statutory authority to issue cease and desist orders and to seek injunctive relief against unlicensed contracting activity. Criminal penalties, by contrast, are imposed through the courts.

Question 19Arizona Statutes, Rules, and Contractor Licensing Requirements

Which of the following is exempt from Arizona contractor licensing requirements?

  1. A company installing HVAC units for a licensed general contractor
  2. A handyman performing $5,000 of repairs for a neighbor
  3. A person building a home for resale to the public
  4. An owner building a residence for the owner's own use Correct answer.

Explanation

An owner who builds or improves a residence for the owner's own occupancy and use is exempt from contractor licensing. Building for resale, performing paid repairs above the threshold, and installing HVAC as a trade all require a license.

Question 20Arizona Statutes, Rules, and Contractor Licensing Requirements

Employees of a properly licensed Arizona contractor who perform work within the scope of the company's license:

  1. are not required to hold individual contractor licenses Correct answer.
  2. must each obtain their own specialty license
  3. must register individually with the Registrar every year
  4. must be listed on the license as qualifying parties

Explanation

Employees working under the direction of a licensed contractor are covered by the employer's license and do not need contractor licenses of their own. Only the business entity, through its qualifying party, holds the license.

Question 21Arizona Statutes, Rules, and Contractor Licensing Requirements

Before submitting a bid on a project that requires a contractor's license, a person must:

  1. post the bid publicly for ten days
  2. file a bid bond with the Registrar
  3. hold the required Arizona license Correct answer.
  4. register with the county recorder

Explanation

Arizona prohibits a person from bidding on or offering to contract for work that requires a license unless the person holds the appropriate license. Bidding without a license is itself a violation.

Question 22Arizona Statutes, Rules, and Contractor Licensing Requirements

As part of a disciplinary order, the Registrar of Contractors may require a contractor to:

  1. pay restitution to the injured property owner Correct answer.
  2. serve jail time of up to six months
  3. perform community service at the agency office
  4. forfeit the contractor's personal residence

Explanation

The Registrar may order a contractor to pay restitution to an owner harmed by the contractor's violations, along with other administrative remedies such as suspension or civil penalties. Incarceration and property forfeiture are criminal penalties imposed by courts.

Question 23Arizona Statutes, Rules, and Contractor Licensing Requirements

A contractor licensed in Nevada wants to perform a single HVAC installation project in Arizona. The contractor must:

  1. notify the Registrar and pay a one-time project fee in lieu of licensing
  2. rely on the Nevada license because contractor licensing is reciprocal
  3. obtain an Arizona contractor's license before contracting for the work Correct answer.
  4. have an unlicensed Arizona worker sign the contract on its behalf

Explanation

Arizona licensing is not reciprocal with other states; an out-of-state contractor must hold an Arizona license to contract for work in the state, regardless of how small the project is. There is no single-project permit that substitutes for a license.

Question 24Arizona Statutes, Rules, and Contractor Licensing Requirements

Before the Registrar suspends or revokes a contractor's license, the licensee is entitled to:

  1. a full refund of all licensing fees paid
  2. notice of the charges and an opportunity for a hearing Correct answer.
  3. a 90-day period to cure the violation as a matter of right
  4. a jury trial in superior court

Explanation

Disciplinary action requires notice to the licensee of the charges and an opportunity for a hearing, protecting the licensee's due process rights. A court trial and an automatic cure period are not part of the administrative process.

Question 25Arizona Statutes, Rules, and Contractor Licensing Requirements

A contractor's license expires and is not renewed, yet the contractor keeps taking new HVAC jobs. The resulting contracts are:

  1. uncollectible in court and subject to unlicensed-contracting penalties Correct answer.
  2. enforceable if the contractor pays a late renewal fee to the Registrar
  3. enforceable because renewal of the license applies retroactively to the expiration date
  4. valid because the contractor held a valid license during the prior term

Explanation

Once a license expires and is not renewed, further contracting is unlicensed activity, exposing the contractor to administrative and criminal penalties and barring an action to collect compensation. The earlier license term does not cover work performed after expiration.

Question 26Arizona Statutes, Rules, and Contractor Licensing Requirements

Arizona generally requires a person to hold a contractor's license to perform construction work when the total contract price for the project is at least:

  1. $2,500
  2. $500
  3. $5,000
  4. $1,000 Correct answer.

Explanation

Arizona law sets the contractor licensing threshold at $1,000 for the total contract price. Work below that amount is generally treated as minor or casual and does not require a contractor's license.

Question 27Arizona Statutes, Rules, and Contractor Licensing Requirements

An Arizona contractor license that authorizes both residential and commercial contracting is classified as:

  1. Specialty
  2. Dual Correct answer.
  3. Combined
  4. General

Explanation

Arizona issues residential, commercial, and dual contractor licenses. A dual license permits the licensee to contract for both residential and commercial work within the licensed classification.

Question 28Arizona Statutes, Rules, and Contractor Licensing Requirements

A sole proprietor who holds an Arizona HVAC contractor license forms an LLC and transfers the business to the LLC. What must the contractor do?

  1. Notify the Registrar within 30 days and keep the existing license
  2. Apply for a new license in the LLC's name Correct answer.
  3. Add the LLC as an additional named insured on the license bond
  4. File a trade name with the Corporation Commission and keep the license

Explanation

An Arizona contractor license is issued to a specific legal entity. When the licensed business is transferred to a new entity such as an LLC, the new entity must apply for and obtain its own contractor license.

Question 29Arizona Statutes, Rules, and Contractor Licensing Requirements

Which statement about the investigative authority of the Arizona Registrar of Contractors is correct?

  1. The Registrar may investigate only licensed contractors, not unlicensed persons.
  2. The Registrar must refer every complaint to the Attorney General before investigating.
  3. The Registrar may open an investigation on its own initiative. Correct answer.
  4. The Registrar may investigate only after the property owner files a written complaint.

Explanation

The Registrar has authority to investigate possible violations on its own motion as well as in response to complaints. This allows the agency to act when it learns of unlicensed or improper contracting activity.

Question 30Arizona Statutes, Rules, and Contractor Licensing Requirements

A firm submits a bid for a municipal HVAC project but does not hold an Arizona contractor license on the bid date. It obtains a license before the contract is awarded. How should the public entity treat the bid?

  1. Reject it because licensure is required at the time of bid Correct answer.
  2. Accept it if the firm pays a late-licensing fee
  3. Accept it because the firm is licensed at award
  4. Hold the bid until the license is issued

Explanation

Arizona requires a bidder on a project that requires a contractor's license to be licensed at the time the bid is submitted. Later licensure before award does not cure the lack of license on the bid date.

Question 31Refrigeration Theory, Refrigerants, and System Components

What is the primary function of the compressor in a vapor-compression refrigeration system?

  1. Reduce refrigerant pressure before the evaporator
  2. Store liquid refrigerant for the cooling cycle
  3. Remove heat from the indoor air
  4. Increase refrigerant pressure and temperature Correct answer.

Explanation

The compressor draws low-pressure vapor from the evaporator and discharges it at a higher pressure, which raises the saturation temperature so the condenser can reject heat to the surroundings. Its work input is what drives the entire cycle. Heat removal and pressure reduction happen at the evaporator and metering device.

Question 32Refrigeration Theory, Refrigerants, and System Components

In an air-cooled refrigeration system, which component rejects heat to the outdoor air?

  1. Compressor
  2. Condenser Correct answer.
  3. Evaporator
  4. Expansion valve

Explanation

The condenser is the heat-rejection coil, where desuperheating, condensation and subcooling occur as outdoor air carries heat away from the refrigerant. The evaporator absorbs heat from the conditioned space, and the compressor and metering device do not reject heat outdoors.

Question 33Refrigeration Theory, Refrigerants, and System Components

What happens to the refrigerant as it passes through the evaporator coil?

  1. It condenses from vapor to liquid
  2. It is compressed to a higher pressure
  3. It boils from liquid to vapor Correct answer.
  4. It is filtered and dried

Explanation

In the evaporator the refrigerant enters as a low-pressure liquid and absorbs heat from its surroundings, boiling to vapor. Condensation is the opposite process and takes place in the condenser. Filtration and pressure rise occur elsewhere in the circuit.

Question 34Refrigeration Theory, Refrigerants, and System Components

What is the primary job of the thermostatic expansion valve?

  1. Circulate air across the evaporator coil
  2. Maintain a constant compressor discharge pressure
  3. Absorb heat from the conditioned space
  4. Meter refrigerant into the evaporator Correct answer.

Explanation

The expansion valve throttles high-pressure liquid down to evaporator pressure and modulates flow to hold a set superheat at the evaporator outlet, forming the boundary between the high side and the low side. It does not move air, absorb heat, or set discharge pressure.

Question 35Refrigeration Theory, Refrigerants, and System Components

Superheat is the number of degrees by which a vapor is:

  1. Above its saturation temperature Correct answer.
  2. Below the ambient air temperature
  3. Below its saturation temperature at the same pressure
  4. Above atmospheric pressure

Explanation

Superheat measures how far a vapor has been heated beyond its saturation temperature at the existing pressure. It is a temperature difference, not a pressure or an ambient comparison. Subcooling is the corresponding measurement for a liquid.

Question 36Refrigeration Theory, Refrigerants, and System Components

Subcooling is calculated as the difference between the condenser saturation temperature and the:

  1. Suction line temperature
  2. Actual liquid line temperature Correct answer.
  3. Compressor discharge temperature
  4. Outdoor ambient temperature

Explanation

Subcooling compares the measured liquid line temperature with the saturation temperature corresponding to the liquid line pressure. The difference shows how far the liquid has been cooled below condensing temperature. Suction and discharge temperatures describe the vapor side of the system.

Question 37Refrigeration Theory, Refrigerants, and System Components

Which refrigerant is a hydrochlorofluorocarbon being phased out because it contains chlorine and depletes stratospheric ozone?

  1. R-410A
  2. R-744
  3. R-22 Correct answer.
  4. R-134a

Explanation

R-22 is an HCFC that carries chlorine to the stratosphere and has a measurable ozone depletion potential, so its production and use are being phased out under the Montreal Protocol. R-410A and R-134a are HFCs with zero ozone depletion potential, and R-744 is carbon dioxide.

Question 38Refrigeration Theory, Refrigerants, and System Components

Which statement is true of refrigerant at saturation inside a closed vessel?

  1. The liquid has completely boiled away to vapor
  2. Liquid and vapor are in equilibrium Correct answer.
  3. The vessel contains only liquid refrigerant
  4. No pressure exists inside the sealed vessel

Explanation

At saturation, liquid and vapor coexist in equilibrium at one temperature and its corresponding pressure. Adding or removing heat at that point changes the proportions of liquid and vapor rather than the temperature. A pure refrigerant at saturation is never limited to a single phase.

Question 39Refrigeration Theory, Refrigerants, and System Components

A thermostatic expansion valve regulates refrigerant flow based on the temperature and pressure it senses at the:

  1. Evaporator outlet suction line Correct answer.
  2. Liquid line at the condenser outlet
  3. Middle of the condenser coil
  4. Compressor discharge line

Explanation

The remote bulb is clamped to the suction line at the evaporator outlet and senses the superheat of the leaving vapor. The valve opens or closes to hold that superheat at its setting. Sensing points elsewhere would not reflect evaporator performance.

Question 40Refrigeration Theory, Refrigerants, and System Components

A liquid line filter drier is installed primarily to:

  1. Reduce the refrigerant pressure
  2. Trap moisture and dirt Correct answer.
  3. Increase the evaporator superheat
  4. Store excess refrigerant during the off cycle

Explanation

The filter drier contains a desiccant and a screen that remove water and particulate matter from the liquid refrigerant before it reaches the metering device. It does not create a meaningful pressure drop or control superheat. Storing excess charge is the receiver's role.

Question 41Refrigeration Theory, Refrigerants, and System Components

The purpose of a crankcase heater is to:

  1. Keep refrigerant out of the crankcase oil Correct answer.
  2. Keep the condenser coil free of frost
  3. Warm the refrigerant entering the evaporator
  4. Raise the compressor discharge temperature

Explanation

During the off cycle the crankcase heater keeps the oil warmer than the coldest part of the system, so refrigerant does not condense into and dilute the oil. Diluted oil loses lubricity and foams or slugs at startup. It plays no role in evaporator or condenser performance.

Question 42Refrigeration Theory, Refrigerants, and System Components

A suction line accumulator is used to:

  1. Keep liquid out of the compressor Correct answer.
  2. Store liquid refrigerant for the heating cycle
  3. Increase the pressure drop across the metering device
  4. Reduce the condensing temperature in cold weather

Explanation

The accumulator is a vessel on the suction line that traps any liquid that did not boil off in the evaporator and lets it vaporize before it reaches the compressor, protecting against slugging. It has no function in condensing or metering.

Question 43Refrigeration Theory, Refrigerants, and System Components

A zeotropic blend such as R-407C is characterized by:

  1. A single saturation temperature at a given pressure
  2. A temperature glide during phase change Correct answer.
  3. The ability to be topped off without measuring
  4. Behavior identical to an azeotropic mixture

Explanation

The components of a zeotropic blend have different boiling points, so the mixture's temperature changes as it evaporates or condenses at constant pressure, a behavior called glide. Because the blend can fractionate during a leak, it must be charged as a liquid and never simply topped off.

Question 44Refrigeration Theory, Refrigerants, and System Components

Air that leaks into a refrigeration system and collects in the condenser will:

  1. Raise head pressure and condensing temperature Correct answer.
  2. Act as a lubricant for the compressor
  3. Lower the discharge pressure and cut the amp draw
  4. Improve heat transfer at the condenser coil

Explanation

Non-condensable gases such as air cannot liquefy at normal condensing temperatures, so they blanket condenser surface and raise both head pressure and condensing temperature. The result is higher amp draw and reduced capacity. Air adds no lubrication and does not improve heat transfer.

Question 45Refrigeration Theory, Refrigerants, and System Components

Flash gas in the liquid line ahead of the metering device:

  1. Has no measurable effect on system performance
  2. Reduces liquid available to absorb heat Correct answer.
  3. Increases the refrigeration capacity of the evaporator coil
  4. Improves the subcooling measured at the condenser outlet

Explanation

When liquid refrigerant flashes to vapor before the metering device, that vapor occupies line volume that would otherwise carry liquid, so less liquid reaches the evaporator to boil and absorb heat. Capacity drops and the valve may hunt. Common causes are a restriction or insufficient subcooling.

Question 46Refrigeration Theory, Refrigerants, and System Components

A superheat reading near zero at the evaporator outlet indicates:

  1. A shortage of refrigerant in the system
  2. Risk of liquid reaching the compressor Correct answer.
  3. A restricted liquid line filter drier
  4. A condenser rejecting too much heat

Explanation

Superheat near zero means the refrigerant is still at its saturation temperature when it leaves the evaporator, so some liquid is likely being carried into the suction line, risking slugging and compressor damage. An undercharge or a liquid line restriction would raise superheat instead.

Question 47Refrigeration Theory, Refrigerants, and System Components

A system has a suction pressure of 60 psig and a discharge pressure of 200 psig. What is the compression ratio using absolute pressures?

  1. 4.2
  2. 2.9 Correct answer.
  3. 2.5
  4. 3.3

Explanation

Convert both gauge readings to absolute by adding about 14.7 psi, giving 74.7 psia suction and 214.7 psia discharge. Dividing 214.7 by 74.7 yields approximately 2.9. Using gauge pressures directly would give an inaccurate ratio.

Question 48Refrigeration Theory, Refrigerants, and System Components

The suction line on a direct-expansion system is insulated to:

  1. Prevent heat gain and condensation on the line Correct answer.
  2. Keep the refrigerant subcooled before the valve
  3. Prevent the pipe from freezing shut
  4. Reduce the noise of the compressor

Explanation

The suction line carries cold vapor, so insulation limits heat pickup that would raise superheat and reduce capacity, and it prevents sweating or frost on the pipe. Subcooling applies to the liquid line, not the suction line.

Question 49Refrigeration Theory, Refrigerants, and System Components

On a system with a thermostatic expansion valve, subcooling well above the design value most likely indicates:

  1. An overcharge of refrigerant Correct answer.
  2. A refrigerant undercharge
  3. A failed condenser fan motor
  4. A restricted suction line

Explanation

Because the expansion valve holds superheat, excess refrigerant has nowhere to go and backs up in the condenser, increasing the liquid subcooling. A failed condenser fan raises head pressure but does not by itself create excess subcooling at the condenser outlet. An undercharge reduces subcooling.

Question 50Refrigeration Theory, Refrigerants, and System Components

Compared with a reciprocating compressor of similar capacity, a scroll compressor:

  1. Compresses continuously with fewer moving parts Correct answer.
  2. Requires no lubricating oil in the crankcase
  3. Relies on a piston and connecting rod assembly
  4. Can be used only with HCFC refrigerants

Explanation

A scroll compressor uses two intermeshing spiral members, one fixed and one orbiting, to compress gas continuously without reciprocating pistons or suction and discharge valves. It still requires oil for lubrication and sealing and is available for many refrigerant types.