Tennessee Contractor Mechanical HVAC and Refrigeration Contractor Examination Practice Test
This practice page addresses HVAC and refrigeration knowledge used in mechanical contracting, including electrical controls, air-side measurements, refrigerant behavior, and system components. The question bank samples practical calculations and troubleshooting decisions, from interpreting a pressure-temperature relationship to checking control voltage and assessing cooling capacity.
Exam overview
About the Tennessee Contractor Mechanical HVAC and Refrigeration Contractor … Exam
The sampled work connects measurement results to equipment operation and safe service procedures. Questions involve distinguishing saturation temperature from other refrigerant conditions, converting Btu/h to refrigeration tons, and calculating the temperature change across a cooling coil. They also address multimeter use, including checking resistance only on a de-energized circuit, and confirming transformer secondary voltage before replacing a thermostat. Refrigeration topics include the roles of evaporators and condensers, compressor capacitors, flare-joint torque, and piping practices that support oil return through vertical risers. Hydronic air purging appears as a circulation and heat-transfer concern. Use these topics to practice interpreting readings, selecting the relevant calculation, and connecting a component’s function to a troubleshooting or installation decision; the bank signals describe practice content, not verified exam requirements.
Sample Practice Questions
Review a selection from this exam's published US Practice Tests practice bank.
When checking a thermostat's low-voltage control circuit, why is it important to verify the transformer secondary voltage before condemning the thermostat?
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Correct answer: AThe transformer supplies low-voltage power to many HVAC control circuits. If that supply is absent or incorrect, the system may not respond even if the thermostat is functioning, so checking the source of control power is a useful diagnostic step.
A refrigerant pressure gauge reads 120 psig on a system using a refrigerant whose pressure-temperature chart gives a saturation temperature of 40°F at that pressure. What does this temperature represent for refrigerant at saturation?
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Correct answer: BA refrigerant pressure-temperature chart pairs saturation pressure with saturation temperature. The chart value is not necessarily the actual measured refrigerant temperature; it is the temperature at which liquid and vapor would be in equilibrium at that pressure.
An air-conditioning system has a measured total cooling capacity of 36,000 Btu/h. Approximately how many tons of refrigeration is that?
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Correct answer: COne ton of refrigeration is conventionally equal to 12,000 Btu/h. Dividing 36,000 by 12,000 gives 3 tons.
A technician measures the supply and return air temperatures across a cooling coil. Which calculation gives the coil's air temperature difference?
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Correct answer: AFor a cooling coil, the air temperature drop is the entering return-air temperature minus the leaving supply-air temperature. This difference is one basic diagnostic measurement and does not by itself establish system capacity.
A technician is testing an HVAC control circuit with a multimeter. What is the safest general practice when measuring resistance?
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Correct answer: BResistance measurements should be made on a de-energized circuit, with absence of voltage verified. Applying resistance mode to an energized circuit can damage the meter and create a safety hazard.
A hydronic heating loop is being filled after maintenance. What is the purpose of purging air from the loop?
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Correct answer: ATrapped air can obstruct water flow, produce gurgling or other noise, and interfere with heat delivery. Purging helps establish a continuous water path through the hydronic circuit.
A technician is laying out refrigerant piping for a system with an indoor unit above the compressor. Why should the manufacturer's piping instructions be followed for vertical risers and oil return?
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Correct answer: ARefrigerant piping size and arrangement affect refrigerant velocity and oil transport, particularly in vertical risers. Manufacturer guidance accounts for equipment and operating conditions and should be followed.
How to use this practice test
Access the practice questions free of charge. Each session presents up to 20 random questions from the 50-question bank, then displays your results. Use missed items to identify whether you need to revisit a calculation, instrument-safety step, refrigeration-cycle function, or installation principle.
Preparation tips
- Practice converting cooling capacity from Btu/h to tons using 12,000 Btu/h per ton, and check that the units match the requested result.
- For coil temperature-difference problems, identify the supply and return readings and subtract in the order specified by the question.
- Before resistance measurements, isolate power and verify the circuit is de-energized; distinguish this procedure from voltage testing on an energized circuit.
- Review how pressure-temperature charts relate pressure to saturation temperature, and distinguish that value from superheat or subcooling.
- Trace the vapor-compression cycle by component function, and connect vertical refrigerant-riser piping guidance to oil return and manufacturer instructions.