NEW MEXICO MECHANICAL CONTRACTOR LICENSE EXAM
(MM-98) COMPLETE EXAM QUESTIONS AND VERIFIED
ANSWERS | 2026–2027 LATEST UPDATE | GUARANTEED PASS
| DETAILED RATIONALES | FULL STUDY GUIDE | EXAM PREP |
PRACTICE TEST | CERTIFICATION PREPARATION
SECTION ONE — QUESTIONS 1–100
1. What is the minimum number of years of work experience required to qualify for the New
Mexico MM-98 Mechanical Contractor license?
A) 2 years
B) 4 years
C) 6 years
D) 8 years
Correct Answer: B) 4 years
Rationale: The New Mexico Regulation and Licensing Department's Construction Industries Division
(CID) requires a qualifying individual for an MM-98 license to have a minimum of 4 years (8,000
hours) of verifiable journeyman-level work experience in the mechanical trades. This is a core
eligibility requirement for the examination process .
2. Which of the following topics is NOT a primary subject area for the MM-1 Plumbing exam?
A) Backflow prevention
B) Isometric analysis
C) Refrigerants and refrigeration
D) Drainage waste and vents
Correct Answer: C) Refrigerants and refrigeration
Rationale: The MM-1 Plumbing exam covers DWV systems, water supply, backflow prevention, storm
drainage, and septic systems . Refrigerants and refrigeration are a primary topic for the MM-3 HVAC
exam, making option C the only choice not covered under the MM-1 scope .
3. A contractor is selecting a pipe for an underground water service line. Which type of copper
tubing is required for this application due to its thickest wall?
A) Type K
B) Type L
C) Type M
D) Type DWV
Correct Answer: A) Type K
Rationale: Type K copper tubing has the thickest wall of the standard copper pipe types and is the
industry standard for underground burial and heavy-duty plumbing applications due to its strength
and durability. Types L and M have thinner walls, and DWV is for drain, waste, and vent applications .
,4. What is the primary purpose of an expansion tank in a hydronic heating system?
A) To circulate water through the system
B) To add heat to the water
C) To accommodate the changing volume of water as it heats
D) To filter debris from the water
Correct Answer: C) To accommodate the changing volume of water as it heats
Rationale: As water is heated in a closed hydronic system, it expands. An expansion tank provides a
space with a compressible air cushion to absorb this increased volume, preventing the system
pressure from rising to unsafe levels and activating the relief valve .
5. The MM-4 Heat, Cooling, and Process Pipe exam consists of how many questions?
A) 50
B) 90
C) 100
D) 250
Correct Answer: B) 90
Rationale: The MM-4 exam has 90 questions, making it the only trade exam for the MM-98 license
that does not have 100 questions. The Business and Law exam has 50 questions, and the other trade
exams (MM-1, MM-2, MM-3) each have 100 questions .
6. According to the International Mechanical Code (IMC), what is the minimum clearance required
in front of a furnace combustion chamber for service access?
A) 18 inches
B) 24 inches
C) 30 inches
D) 36 inches
Correct Answer: C) 30 inches
Rationale: Mechanical codes mandate a clear working space in front of appliances like furnaces for
safe service and maintenance. The standard requirement is a minimum depth of 30 inches and a
width of 30 inches, allowing technicians adequate room to perform their work .
7. Which law of physics is fundamental to understanding the behavior of gases and states that the
pressure of a gas is inversely proportional to its volume when the temperature is held constant?
A) Charles' Law
B) Boyle's Law
C) Dalton's Law
D) Henry's Law
Correct Answer: B) Boyle's Law
Rationale: Boyle's Law describes the inverse relationship between pressure and volume in a gas at a
constant temperature. This is a core principle in thermodynamics, essential for understanding
compression and expansion cycles in HVAC and refrigeration systems. Charles' Law relates volume
and temperature .
8. When testing a natural gas piping system with air, what is the minimum required test pressure?
A) 1.5 times the maximum working pressure, but not less than 3 psi
, B) 10 psi
C) 5 psi
D) 3 psi
Correct Answer: A) 1.5 times the maximum working pressure, but not less than 3 psi
Rationale: Code requires that a gas piping system be tested to a pressure of at least 1.5 times the
proposed maximum working pressure. The test pressure must not be less than 3 psi, ensuring the test
is robust enough to identify any leaks in the system .
9. A system administrator is troubleshooting a 3-phase motor that is drawing unbalanced currents.
What is the most likely cause of this issue?
A) An incorrect service factor
B) A loose or corroded connection
C) An undersized contactor
D) High ambient temperature
Correct Answer: B) A loose or corroded connection
Rationale: Unbalanced currents in a 3-phase motor are most often caused by unbalanced voltages,
which stem from issues like loose connections, corroded terminals, or a faulty transformer. Other
options are less likely to cause current imbalance directly; high ambient temperature or incorrect
service factor would more directly affect motor overheating or capacity .
10. What is the primary function of a thermal expansion valve (TXV) in a refrigeration system?
A) To control the amount of refrigerant flowing into the condenser
B) To regulate the superheat at the evaporator outlet
C) To increase the pressure of the refrigerant
D) To filter the refrigerant
Correct Answer: B) To regulate the superheat at the evaporator outlet
Rationale: The TXV is a metering device that controls the flow of refrigerant into the evaporator. Its
primary goal is to maintain a constant superheat at the evaporator outlet, ensuring that the
evaporator is fully utilized without allowing liquid refrigerant to return to the compressor .
11. According to ASHRAE Standard 62.1, the primary method for determining outdoor air
ventilation rates is based on which two factors?
A) Total square footage and climate zone
B) Number of occupants and the type of heating fuel
C) Number of occupants and the floor area
D) Floor area and the outside temperature
Correct Answer: C) Number of occupants and the floor area
Rationale: ASHRAE Standard 62.1's Ventilation Rate Procedure calculates the required outdoor
airflow based on both the number of building occupants and the floor area of the space. This ensures
adequate ventilation to maintain acceptable indoor air quality (IAQ) .
12. A mechanical contractor witnesses a safety violation on a job site. What is the correct ethical
and professional action to take?
A) Ignore the violation if it is not an immediate danger
B) Report the violation to the site supervisor immediately
(MM-98) COMPLETE EXAM QUESTIONS AND VERIFIED
ANSWERS | 2026–2027 LATEST UPDATE | GUARANTEED PASS
| DETAILED RATIONALES | FULL STUDY GUIDE | EXAM PREP |
PRACTICE TEST | CERTIFICATION PREPARATION
SECTION ONE — QUESTIONS 1–100
1. What is the minimum number of years of work experience required to qualify for the New
Mexico MM-98 Mechanical Contractor license?
A) 2 years
B) 4 years
C) 6 years
D) 8 years
Correct Answer: B) 4 years
Rationale: The New Mexico Regulation and Licensing Department's Construction Industries Division
(CID) requires a qualifying individual for an MM-98 license to have a minimum of 4 years (8,000
hours) of verifiable journeyman-level work experience in the mechanical trades. This is a core
eligibility requirement for the examination process .
2. Which of the following topics is NOT a primary subject area for the MM-1 Plumbing exam?
A) Backflow prevention
B) Isometric analysis
C) Refrigerants and refrigeration
D) Drainage waste and vents
Correct Answer: C) Refrigerants and refrigeration
Rationale: The MM-1 Plumbing exam covers DWV systems, water supply, backflow prevention, storm
drainage, and septic systems . Refrigerants and refrigeration are a primary topic for the MM-3 HVAC
exam, making option C the only choice not covered under the MM-1 scope .
3. A contractor is selecting a pipe for an underground water service line. Which type of copper
tubing is required for this application due to its thickest wall?
A) Type K
B) Type L
C) Type M
D) Type DWV
Correct Answer: A) Type K
Rationale: Type K copper tubing has the thickest wall of the standard copper pipe types and is the
industry standard for underground burial and heavy-duty plumbing applications due to its strength
and durability. Types L and M have thinner walls, and DWV is for drain, waste, and vent applications .
,4. What is the primary purpose of an expansion tank in a hydronic heating system?
A) To circulate water through the system
B) To add heat to the water
C) To accommodate the changing volume of water as it heats
D) To filter debris from the water
Correct Answer: C) To accommodate the changing volume of water as it heats
Rationale: As water is heated in a closed hydronic system, it expands. An expansion tank provides a
space with a compressible air cushion to absorb this increased volume, preventing the system
pressure from rising to unsafe levels and activating the relief valve .
5. The MM-4 Heat, Cooling, and Process Pipe exam consists of how many questions?
A) 50
B) 90
C) 100
D) 250
Correct Answer: B) 90
Rationale: The MM-4 exam has 90 questions, making it the only trade exam for the MM-98 license
that does not have 100 questions. The Business and Law exam has 50 questions, and the other trade
exams (MM-1, MM-2, MM-3) each have 100 questions .
6. According to the International Mechanical Code (IMC), what is the minimum clearance required
in front of a furnace combustion chamber for service access?
A) 18 inches
B) 24 inches
C) 30 inches
D) 36 inches
Correct Answer: C) 30 inches
Rationale: Mechanical codes mandate a clear working space in front of appliances like furnaces for
safe service and maintenance. The standard requirement is a minimum depth of 30 inches and a
width of 30 inches, allowing technicians adequate room to perform their work .
7. Which law of physics is fundamental to understanding the behavior of gases and states that the
pressure of a gas is inversely proportional to its volume when the temperature is held constant?
A) Charles' Law
B) Boyle's Law
C) Dalton's Law
D) Henry's Law
Correct Answer: B) Boyle's Law
Rationale: Boyle's Law describes the inverse relationship between pressure and volume in a gas at a
constant temperature. This is a core principle in thermodynamics, essential for understanding
compression and expansion cycles in HVAC and refrigeration systems. Charles' Law relates volume
and temperature .
8. When testing a natural gas piping system with air, what is the minimum required test pressure?
A) 1.5 times the maximum working pressure, but not less than 3 psi
, B) 10 psi
C) 5 psi
D) 3 psi
Correct Answer: A) 1.5 times the maximum working pressure, but not less than 3 psi
Rationale: Code requires that a gas piping system be tested to a pressure of at least 1.5 times the
proposed maximum working pressure. The test pressure must not be less than 3 psi, ensuring the test
is robust enough to identify any leaks in the system .
9. A system administrator is troubleshooting a 3-phase motor that is drawing unbalanced currents.
What is the most likely cause of this issue?
A) An incorrect service factor
B) A loose or corroded connection
C) An undersized contactor
D) High ambient temperature
Correct Answer: B) A loose or corroded connection
Rationale: Unbalanced currents in a 3-phase motor are most often caused by unbalanced voltages,
which stem from issues like loose connections, corroded terminals, or a faulty transformer. Other
options are less likely to cause current imbalance directly; high ambient temperature or incorrect
service factor would more directly affect motor overheating or capacity .
10. What is the primary function of a thermal expansion valve (TXV) in a refrigeration system?
A) To control the amount of refrigerant flowing into the condenser
B) To regulate the superheat at the evaporator outlet
C) To increase the pressure of the refrigerant
D) To filter the refrigerant
Correct Answer: B) To regulate the superheat at the evaporator outlet
Rationale: The TXV is a metering device that controls the flow of refrigerant into the evaporator. Its
primary goal is to maintain a constant superheat at the evaporator outlet, ensuring that the
evaporator is fully utilized without allowing liquid refrigerant to return to the compressor .
11. According to ASHRAE Standard 62.1, the primary method for determining outdoor air
ventilation rates is based on which two factors?
A) Total square footage and climate zone
B) Number of occupants and the type of heating fuel
C) Number of occupants and the floor area
D) Floor area and the outside temperature
Correct Answer: C) Number of occupants and the floor area
Rationale: ASHRAE Standard 62.1's Ventilation Rate Procedure calculates the required outdoor
airflow based on both the number of building occupants and the floor area of the space. This ensures
adequate ventilation to maintain acceptable indoor air quality (IAQ) .
12. A mechanical contractor witnesses a safety violation on a job site. What is the correct ethical
and professional action to take?
A) Ignore the violation if it is not an immediate danger
B) Report the violation to the site supervisor immediately
