Previous NATE Air Distribution Service Practice Test 9

NATE_AIRDIST_SERVICE NEC 2023

NATE Air Distribution Service Practice Test 10

This final review test mixes scenario-based troubleshooting across the full air distribution blueprint: a room too hot or cold, noisy ducts, high static pressure, duct leakage, zoning, blower motor behavior, and filter trade-offs.

TOPICS COVERED

NATE Air Distribution Service

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Frequently Asked Questions

Yes — completely free with no signup required. Every question includes a full explanation of the correct answer.

Two: the NATE Core exam plus at least one specialty exam (for example AC Service, Heat Pump Service, or Air Distribution Service). You can take them on the same day or separately.

The Core exam has 50 questions and each installation or service specialty exam has 100 questions. You need 70% on each to pass — 35 of 50 on Core and 70 of 100 on a specialty. Check natex.org for the current format before you book.

NATE certification lasts two years. To renew, you submit 16 hours of continuing education or retake the specialty exam before your certification expires.

No. These are independent practice tests written to match the published NATE exam topics. They are not official NATE exam questions.

Exam Tip: When a scenario gives you several symptoms, work through the airflow path step by step: filter, coil, dampers, ducts, and blower behavior, before jumping to a conclusion.

30

Questions

30 min

Time

70%

Pass

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NATE Air Distribution Service Practice Test 10 — Question List

Question 1: A homeowner says one upstairs bedroom is always too warm in summer. The register has decent airflow, but the door is normally kept closed with no return path. What is the most likely contributor?

The room becomes pressurized with no return path, pushing conditioned air back out through gaps around the door
The refrigerant charge is too high
The thermostat is defective
The blower motor is undersized for the whole house

Question 2: A homeowner complains of a loud whistling noise at a supply register that started recently. What is a reasonable first thing to check?

The color of the register grille
Whether the filter has become dirty, since increased resistance can raise air velocity and noise at registers
The refrigerant type used by the system
The homeowner's thermostat brand

Question 3: A technician measures TESP at 0.90 in. w.c. on equipment rated for 0.50 in. w.c. What should the technician do next?

Assume the reading is a mistake and ignore it
Immediately replace the outdoor condensing unit
Investigate common restriction points, such as the filter, coil, dampers, and duct condition, to find the cause of the excess resistance
Increase the refrigerant charge to compensate

Question 4: A two-story home has a zoning system, and the downstairs zone is often too cool while the upstairs is too warm, even though both zones seem to call normally. What area should be investigated?

The color of the thermostats in each zone
The refrigerant type used by the outdoor unit
The homeowner's furniture placement upstairs
Whether the zone dampers are operating correctly and whether the system's airflow (including any bypass) is properly balanced for both zones

Question 5: True or False: A room with low measured CFM at its register could be caused by a duct leak, a closed damper, or a kinked flex duct run — all are plausible causes worth checking.

True
False, only a closed damper could cause this symptom
False, only a duct leak could cause this symptom
False, low CFM can only be caused by refrigerant issues

Question 6: A system with a PSC blower has been running the same way for years. Suddenly, several rooms show reduced airflow, and TESP is much higher than the rated static pressure. What is a likely explanation?

This is completely normal for any PSC-equipped system
A new restriction has developed, such as a very dirty filter, a dirty coil, or a collapsed duct section, since the PSC motor does not compensate for rising resistance
The refrigerant charge must have doubled
The thermostat has switched from heating to cooling mode

Question 7: A homeowner with an ECM-equipped system says their electric bill increased, but comfort still feels normal. What airflow-related check would help explain this?

This has nothing to do with airflow and should not be investigated
Assume the thermostat is defective without checking airflow
Check static pressure and filter/coil condition, since the ECM motor may be working harder (using more electricity) to maintain CFM against rising resistance
Replace the outdoor unit immediately

Question 8: A technician finds a return duct in an attic with several unsealed seams, and the homeowner reports dusty indoor air and higher-than-expected cooling load. What is the best explanation connecting these symptoms?

The refrigerant charge is causing both symptoms
The thermostat display needs to be replaced
The blower motor type is the sole cause of both symptoms
Return leaks are pulling in hot, dusty attic air, adding both indoor air quality problems and extra heat load on the system

Question 9: A homeowner recently upgraded to a much higher MERV filter and now complains of weak airflow throughout the house. What is the most likely connection?

The higher MERV filter is adding more resistance than the system's blower and ducts were designed to handle, reducing overall airflow
Higher MERV filters always improve airflow
This must be caused by a refrigerant leak
MERV rating has no possible connection to airflow

Question 10: A technician measures 60 CFM at a register designed for 120 CFM. Static pressure at the equipment is within rated limits. What is a likely explanation specific to that one register?

The equipment must be undersized for the whole house
A branch-specific problem, such as a closed balancing damper, a kink in the flex duct, or a leak along that branch's duct run
The refrigerant charge is definitely low
This reading is impossible if static pressure is normal

Question 11: True or False: A properly balanced, well-sealed duct system with a clean filter would generally be expected to show TESP close to the equipment's rated static pressure.

False, a well-maintained system typically reads far above rated static pressure
False, static pressure is unrelated to system condition
True
True, but only during heating mode

Question 12: A homeowner just had a room addition built with a new branch duct tapped into the existing trunk, and now several original rooms have noticeably weaker airflow. What is the most likely explanation?

This is unrelated to the room addition and purely coincidental
The refrigerant charge automatically decreased because of the room addition
The blower motor type automatically changed because of the room addition
The system was not rebalanced (and possibly not resized) after the new branch was added, so airflow is now spread across more branches than the original design intended

Question 13: A technician wants to measure CFM at a supply register to confirm design airflow. Which tool is the most direct choice?

A flow hood
A refrigerant gauge set
A combustion analyzer
A clamp meter

Question 14: A homeowner's system has a bypass damper that seems to be open almost constantly, even with multiple zones calling. What should a technician suspect?

This is completely normal and requires no further attention
The bypass damper may be stuck open or the zoning system's balance/control settings may need review, since this is not typical for normal operation with multiple zones calling
This means the refrigerant charge is too high
This means the filter's MERV rating is too low

Question 15: A furnace rated for 0.50 in. w.c. is measured at 0.25 in. w.c. supply and 0.20 in. w.c. (absolute) return. What is the TESP, and what does it suggest?

TESP = 0.05 in. w.c., which is far above rated static
TESP = 0.70 in. w.c., which is above rated static
TESP = 0.45 in. w.c., which is below rated static, suggesting the system has less resistance than designed for and airflow may be at or above design
TESP cannot be calculated from these two readings

Question 16: A homeowner says their new flex duct installation seems noisier and less effective than the old sheet metal ducts it replaced. What could explain this, assuming both were sized similarly?

Flex duct always performs identically to sheet metal in every installation
This is caused by the refrigerant charge, not the duct material
This is caused by the thermostat brand, not the duct material
The flex duct may not have been pulled tight or properly supported, adding turbulence and resistance compared to the smooth, rigid sheet metal it replaced

Question 17: True or False: A system can pass a static pressure check at the equipment while still having a poorly balanced airflow distribution between rooms.

True
False, normal TESP guarantees perfect room-by-room balance
False, TESP and balance are the same measurement
True, but only in zoned systems

Question 18: A technician troubleshooting low airflow finds: a moderately dirty filter, a slightly dirty coil, and one partly closed damper, all on the same system. What is the best overall assessment?

Only the dirtiest single component matters; the others are irrelevant
All three issues are likely adding to the total resistance, and addressing them together would likely produce a bigger airflow improvement than fixing just one
These three issues would cancel each other out
None of these issues can affect airflow at the same time

Question 19: A homeowner wants to know if adding a zoning system to their existing single-zone home would help their upstairs/downstairs comfort complaint. What is an accurate, balanced answer?

Zoning never helps with upstairs/downstairs comfort complaints
Zoning always solves this problem instantly with no other considerations
Zoning could help by allowing independent temperature control for each level, but it needs to be properly designed and integrated with the existing duct system and blower to work well
Zoning is only relevant to refrigerant charge, not comfort

Question 20: Which combination of readings would most strongly suggest a supply duct leak feeding a specific room, rather than a whole-system restriction?

High TESP and low CFM at every register in the house
Normal TESP and normal CFM at every register in the house
High TESP and high CFM at every register in the house
Normal whole-system TESP and normal CFM at most other registers, but noticeably low CFM at that one room's register

Question 21: A technician is asked to improve comfort in a home without doing a full duct redesign. Which combination of actions best reflects a practical, layered approach?

Check and replace the filter if needed, inspect the coil, verify damper positions, measure CFM at each register, and adjust balancing dampers as needed
Immediately replace all ductwork in the home without any diagnosis
Only check the refrigerant charge and ignore airflow entirely
Tell the homeowner nothing can be done without a full system replacement

Question 22: True or False: Understanding the difference between CFM and static pressure is important for correctly diagnosing most air distribution complaints.

False, these two concepts are not relevant to real troubleshooting
True
False, only static pressure matters; CFM is irrelevant
False, only CFM matters; static pressure is irrelevant

Question 23: A homeowner's system uses an ECM blower and a zoning system together. One small zone is calling alone, and the homeowner mentions the system sounds different than usual. What is a reasonable, informed explanation?

This always indicates a refrigerant leak
This always indicates the thermostat needs to be replaced
With only a small zone open, the ECM motor and any bypass damper are working to manage the resulting change in resistance, which can create different sounds than when more zones are open
ECM motors and zoning systems cannot be used together

Question 24: A technician measures static pressure and CFM before and after sealing several duct leaks. TESP barely changed, but total measured CFM at the registers increased. What does this suggest?

This result is impossible and indicates a measurement error
Sealing ducts can never affect CFM readings
The equipment's rated static pressure must have been wrong
The leaks were mainly causing air to be lost along the way (reducing delivered CFM) rather than being the main source of the system's overall resistance (static pressure)

Question 25: A homeowner asks which single measurement would tell them the most about their system's overall airflow health. What is the most accurate answer?

No single measurement tells the whole story; static pressure, CFM, and a visual inspection of ducts and filters together give a fuller picture
Static pressure alone always tells the complete story
CFM alone always tells the complete story
The thermostat setpoint alone tells the complete story

Question 26: A technician diagnoses a system with high static pressure, finds and fixes a dirty filter and a partly closed damper, then re-measures TESP close to the rated value. What should be documented for future reference?

Nothing needs to be documented once the repair is complete
The before and after TESP readings, the issues found and corrected, and the current damper positions and filter type/MERV rating
Only the homeowner's contact information needs to be recorded
Only the refrigerant charge needs to be documented

Question 27: True or False: A technician should always compare a static pressure reading to the specific equipment's rated value, rather than using a single universal number for every system.

False, every unit shares the exact same rated static pressure
False, rated static pressure is not a real specification
True
True, but only for gas furnaces, not heat pumps

Question 28: A homeowner's complaint is: "The house feels stuffy, energy bills are high, and one bedroom never gets comfortable." Which combination of checks would address the widest range of possible causes?

Only check the refrigerant charge, since that explains every possible symptom
Only check the thermostat batteries
Only replace the outdoor unit without further diagnosis
Check filter and coil condition, measure static pressure and CFM at multiple registers including the problem bedroom, inspect ducts for leaks, and check for a return path in the bedroom

Question 29: A technician completes a full air distribution inspection: filter is clean, coil is clean, static pressure is close to rated, dampers are correctly set, and duct leakage is minimal. Register CFM readings are close to design in every room. What should the technician conclude?

The air distribution system appears to be performing well, and any remaining comfort complaints may be due to other factors outside air distribution, such as insulation or window solar gain
The technician should replace the entire duct system anyway, just to be safe
The technician should assume the readings are wrong and repeat every test indefinitely
The technician should conclude the refrigerant charge is definitely incorrect

Question 30: Overall, what is the best summary of a sound approach to air distribution troubleshooting?

Guess at the cause based on the homeowner's description alone, without measurements
Use measurements (static pressure, CFM) together with visual inspection of filters, coils, dampers, and ducts to systematically identify and address the actual cause of a complaint
Always replace the entire system regardless of findings
Only check refrigerant charge, since airflow is not related to comfort complaints

EXAM CARD NATE_AIRDIST_SERVICE

Questions30

Time limit30 min

Pass score70%

Code editionNEC 2023

DifficultyIntermediate

Last reviewedJun 2026

Timer starts immediately. Progress is auto-saved.

Source: NEC 2026 (NFPA 70)