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The AZ-ACR exam has 80 questions and runs 3 hours 30 minutes.
These 10 free AZ-ACR questions are organized by exam domain, so you can see how each part of the Arizona R-39R/C-39 (CR-39) Air Conditioning and Refrigeration (Residential/Commercial) Examination blueprint is tested. Reveal the answer and explanation under each question.
An operating walk-in cooler has low suction pressure and excessive evaporator-outlet superheat. The coil is ice-free, airflow is correct, and adequately subcooled liquid reaches the liquid-line filter-drier. With ambient heat transfer minimized, matched probes show a 12°F temperature drop across the drier. Which fault best accounts for all these findings?
Correct answer: A - A liquid-line filter-drier restricting refrigerant flow
A thermostatic expansion valve (TXV) system uses a refrigerant blend with temperature glide. At the evaporator outlet, measured pressure corresponds to 40°F dew point and 34°F bubble point. Suction-line temperature at that same location is 52°F. The specified outlet-superheat range is 10°F-14°F under the present stabilized load, and airflow is correct. What superheat should be reported, and what does it indicate?
Correct answer: C - 12°F; outlet superheat is within the specified range.
Water rises in the primary pan of a new draw-through air handler while the blower runs, then drains rapidly when the blower stops. The blower delivers the specified airflow. The coil is not iced, and the drain is clear, slopes continuously to its outlet, and has no trap. What installation change addresses this behavior?
Correct answer: B - Install and prime a condensate trap sized for the pan's operating negative pressure.
On a cold, damp morning, an air-source heat pump in heating mode stops its outdoor fan while the compressor continues running. Water vapor rises from the outdoor coil, auxiliary heat energizes, and visible frost melts. Within the unit's specified defrost interval, the fan restarts and warm-air delivery returns to normal. Which service decision is justified by this sequence?
Correct answer: D - Document normal defrost operation and leave the controls unchanged.
Burners on an induced-draft furnace light smoothly, but the control closes the gas valve three seconds later. The heat call remains present, draft stays proven, and gas inlet pressure remains within the listed range. The control requires at least 1.0 µA DC of flame signal; the measured signal is 0.2 µA DC while the flame is established. Where does the evidence direct the next check?
Correct answer: B - The flame-sensing rod, burner grounding, and flame-contact path
A failed run capacitor for a 230-V permanent split capacitor (PSC) blower motor is marked 10 µF, 370 VAC. A 10-µF, 440-VAC run capacitor in the service vehicle matches the required tolerance, duty, temperature rating, connections, and mounting. The motor and wiring pass inspection, and power is isolated. How should the technician proceed?
Correct answer: D - Install the 10-µF, 440-VAC run capacitor and verify motor operation.
A closed hot-water boiler system now rises from 12 psig cold to 27 psig at its normal operating temperature; commissioning records show a much smaller pressure change over the same temperature range. With system configuration and pump operation unchanged, a test with makeup water positively isolated reproduces the rise. The system is full, the gauge is accurate, and the burner shuts off at the correct water-temperature setting. Which failure most closely fits this pattern?
Correct answer: A - An expansion tank that has lost its effective air cushion
A restaurant's kitchen exhaust fan delivers its scheduled airflow, but the room is strongly negative relative to the dining area. Hood capture improves when an exterior door is briefly opened. The makeup-air fan is running; a duct traverse shows its actual outdoor-air delivery is well below the scheduled value. What correction targets the demonstrated problem without sacrificing required exhaust?
Correct answer: A - Restore the makeup-air system to its scheduled outdoor-air delivery.
During a humid afternoon, a direct evaporative cooler delivers air warmer than the owner expects. Entering air is 100°F dry bulb and 76°F wet bulb; leaving air is 81°F dry bulb. Airflow and media wetting meet the equipment requirements. The service manual specifies 75%-85% saturation effectiveness at these conditions. Report effectiveness to the nearest whole percent and judge it against that specification.
Correct answer: A - 79% effectiveness; performance is within the specified range.
Two gas-fired appliances on a common branch operate correctly when fired separately. With both firing, pressure at both appliance inlets falls below their specified minimums, although pressure at the branch entrance stays within the required range. Both appliance shutoff valves are fully open. Static pressure with neither appliance firing is normal. The next investigation should focus on:
Correct answer: B - The shared branch's sizing and pressure loss under combined appliance demand
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