10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
The MD-JHVACR exam has 100 questions and runs 4 hours.
These 10 free MD-JHVACR questions are organized by exam domain, so you can see how each part of the Maryland Journeyman HVACR License Exam blueprint is tested. Reveal the answer and explanation under each question.
A 230-V permanent split capacitor condenser-fan motor requires a 5-µF, 370-VAC run capacitor. Its failed capacitor must be replaced. A 5-µF, 440-VAC continuous-duty run capacitor matches the required temperature rating, mounting, and terminals, but the original voltage rating is not in stock. Which replacement decision is correct?
Correct answer: D - Use the 5-µF, 440-VAC run capacitor.
A condensing unit's contactor is fully pulled in, but the running compressor receives low voltage. Recorded measurements show 240 VAC at the contactor's line terminals, 24 VAC across its coil, an 18-V drop across the closed L1-T1 pole, and only a 0.1-V drop across the closed L2-T2 pole. The wire terminations are secure. These readings localize the fault to the:
Correct answer: B - High-resistance power contact in the contactor's L1-T1 pole
An air handler drains normally with the blower off. At the required operating airflow, water backs up in the pan and air is drawn inward through the drain outlet. The drain pipe is clear, correctly sized, and properly sloped. What should be corrected before increasing the pipe size?
Correct answer: C - Correct the trap configuration and water seal using the unit's drain detail.
A refrigeration circuit has been recovered and opened for a copper-tubing repair. The replacement metering device must be protected from oxide scale formed inside the tubing during brazing. Which brazing setup is appropriate?
Correct answer: A - Maintain a low flow of dry nitrogen through the tubing during brazing, with the outlet open.
A TXV-equipped split system has poor cooling despite verified evaporator airflow and a normal indoor load. Evaporator-outlet superheat is 28°F, and condenser-outlet subcooling is 18°F; the unit specifies 8-12°F for each. The liquid line has a 12°F temperature drop directly across the filter-drier, with no comparable drop elsewhere. Which fault best explains the complete pattern?
Correct answer: B - A partial restriction in the liquid-line filter-drier
At a zeotropic refrigerant evaporator outlet, the measured pressure corresponds to a 42°F dew-point temperature and a 36°F bubble-point temperature. A properly attached temperature probe at that same location reads 58°F. The equipment's specified outlet-superheat range is 8-12°F. The correct superheat and interpretation are:
Correct answer: A - 16°F; above the specified range
When a walk-in cooler reaches setpoint, its thermostat de-energizes the liquid-line solenoid. The compressor continues running until suction pressure reaches the low-pressure control's specified cutout, then stops. On the next cooling call, the solenoid opens, suction pressure rises to the specified cut-in, and the compressor restarts. The cooler maintains temperature without extra cycling. How should this sequence be classified?
Correct answer: D - Normal pump-down control of the refrigeration system
An induced-draft gas furnace proves draft and lights all burners. Fuel input and manifold pressure are correct, and a stable flame engulfs the flame rod. Four seconds later, the control de-energizes the gas valve while the thermostat still calls for heat. The control requires at least 1.0 µA DC for flame proving; a meter in series with the flame sensor reads 0.2 µA DC. Diagnosis should focus first on the:
Correct answer: A - Flame-sensing and burner-grounding circuit
A hot-water boiler's relief valve has been replaced twice, yet it still discharges during each warm-up. System pressure remains steady at the specified cold-fill pressure. The same behavior occurs with the makeup-water supply isolated. Boiler temperature stays within its operating range, and all heating zones circulate normally. Testing which component is most likely to explain the repeated discharge?
Correct answer: D - The expansion tank and its connection to the system
A cooling system requires 1,100 CFM. At the selected constant-speed blower setting, the manufacturer's table lists 1,200 CFM at 0.30 in. w.c., 1,100 CFM at 0.50 in. w.c., and 950 CFM at 0.70 in. w.c. Measured total external static pressure is 0.70 in. w.c. Filter pressure drop is 0.45 in. w.c.; the filter manufacturer's limit at this flow is 0.20 in. w.c. What do these data support?
Correct answer: C - Airflow is 950 CFM; correct the excessive filter resistance and recheck delivery.
The MD-JHVACR exam also covers these domains. Drill them in the full free practice test:
The full bank has 1,020 more MD-JHVACR questions with explanations.
Continue in the free practice test →
View plans