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The NATE-AIR-DIST-SERVICE exam has 100 questions and runs 2 hours 30 minutes.
These 10 free NATE-AIR-DIST-SERVICE questions are organized by exam domain, so you can see how each part of the Air Distribution Service Technician blueprint is tested. Reveal the answer and explanation under each question.
At the first leakage test after a flex-duct reconnection, air escapes around a plenum collar. The outer jacket is taped in place, but the drawband grips the jacket and insulation; the inner liner ends short of the collar bead. Which repair restores the air seal and mechanical connection?
Correct answer: A - Fit, seal, and secure the liner over the bead; restore insulation and jacket.
For an airflow acceptance test, a rectangular supply duct measures 18 by 12 in. between its sheet-metal walls. One-inch internal liner covers all four walls. A correctly performed equal-area traverse of the clear air passage averages 900 fpm. The project's acceptance range is 1,140-1,260 CFM. The test report should record:
Correct answer: A - 1,000 CFM; below the acceptance range.
The rooms remain warm during a cooling service call. The operating stage requires 1,200 CFM, but a valid traverse measures 780 CFM. The evaporator is not iced and has a 30°F dry-bulb temperature drop. Pressure drop across the installed filter is 0.42 in. w.c.; the specified clean filter is rated 0.10 in. w.c. at the same 780 CFM. The coil and blower wheel are clean. Which action is best supported by these readings?
Correct answer: C - Correct the filter restriction, then remeasure airflow before evaluating refrigerant charge.
A home uses a central hallway return. One bedroom cools normally with its door open but becomes warm after the door is closed at night. Its supply drops from 115 CFM to 70 CFM, and the closed room measures +9 Pa relative to the hallway. Other rooms remain comfortable. The branch damper is fully open and the duct is intact. What modification addresses this pattern most directly?
Correct answer: C - Provide an adequately sized return or transfer-air path from the bedroom.
After total airflow is set correctly, a balancing report shows four branches at these percentages of their scheduled flows: A, 128%; B, 74%; C, 101%; and D, 99%. Branch B's damper is fully open. Its duct and return path have been checked and are clear. No fan adjustment is needed to meet the required total. Where should the balancing adjustment be made next?
Correct answer: D - Throttle branch A gradually, keep B open, and remeasure the branches and total.
Midway through a residential air-balance visit, a carbon monoxide alarm sounds. A resident reports a new headache and nausea. The furnace is running, but the technician has not yet measured room CO. What takes priority over locating the source?
Correct answer: B - Get everyone outdoors and call emergency services from a safe location.
Following a return-duct alteration, a constant-airflow ECM system's total external static pressure rises from 0.40 to 0.65 in. w.c. Its airflow command remains 1,200 CFM, and a valid traverse still confirms 1,200 CFM. Blower RPM and input watts increase. The manufacturer's external-static limit is 0.80 in. w.c.; all motor operating limits are met and no faults are reported. Which assessment fits these observations?
Correct answer: D - The motor is increasing effort to maintain commanded airflow against higher resistance.
An induced-draft furnace stops before ignition because draft is not proved. The specified normally open switch must close as suction increases past 0.60 in. w.c. below its reference pressure. A correctly connected manometer at the switch measures a steady 0.92 in. w.c. below that reference, but control-circuit testing confirms that the contacts remain open. Both pressure ports are clear, the tubing is sound, and the switch has the correct part number. These measurements support:
Correct answer: A - Replacing the proving switch with the specified part and confirming draft proof.
A thermostatic expansion valve is operating within its normal control range. Evaporating pressure is unchanged, but the refrigerant temperature at the evaporator-outlet sensing bulb rises. How does the valve respond to this change?
Correct answer: C - It opens further to increase refrigerant feed and bring outlet superheat back down.
A small office needs 180 CFM from one ceiling diffuser. At that airflow, the design permits a pressure drop no greater than 0.12 in. w.c., a Noise Criterion (NC) rating no greater than 25, and a throw of 7-10 ft to a terminal velocity of 50 fpm. All four models are rated at those same test conditions. Select the diffuser that meets the complete specification.
Correct answer: B - Model K: 0.09 in. w.c. pressure drop, NC 23, and 8-ft throw.
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