ASCS Practice Questions (2026) — Free Sample Questions with Answers

Answer: C

An invoice listing crew labor hours: Hours show time spent, not which components were cleaned or verified.

The crew leader's verbal confirmation: Verbal statements are not documentation.

A report with photos and verification results: Correct: a post-project report with before-and-after photos and documented verification shows that each component in the scope was cleaned and verified.

A certificate of antimicrobial application: Chemical use, if any, is not proof that cleaning was completed.

Document results with photos and verification so the customer can see the scope was met.

Answer: B

apply antimicrobials to all surfaces.: Chemical treatment is an optional step after cleaning, never the objective or a substitute for it.

remove contaminants from the system.: Correct: ACR is built on source removal, physically removing and capturing contaminants from HVAC components so they cannot be re-entrained into occupied space.

coat interior duct surfaces.: Coatings are restoration measures applied, if at all, after cleaning; they do not remove contaminants.

increase outdoor air intake.: Dilution with outdoor air is a ventilation strategy, not the purpose of cleaning.

HVAC cleaning means source removal: dislodge, capture and remove contaminants from the system.

Answer: C

1. Room volume = 20 ft × 30 ft × 10 ft = 6,000 ft³.
2. Hourly airflow = 1,000 ft³/min × 60 min/h = 60,000 ft³/h.
3. ACH = 60,000 ft³/h ÷ 6,000 ft³ = 10 per hour.

0.17: Divides CFM by volume but forgets to multiply by 60 min/h.

6: Inverts the ratio (6,000 ÷ 1,000).

10: Correct: volume = 6,000 ft³; 1,000 × 60 = 60,000 ft³/h; 60,000 ÷ 6,000 = 10 ACH.

100: Uses the 600 ft² floor area instead of the room volume.

ACH = CFM × 60 ÷ room volume (ft³).

Answer: D

multi-zone system.: A multi-zone unit mixes hot and cold deck air at the air handler and sends one duct to each zone.

single-zone constant volume system.: A single-zone system has one supply duct serving one zone.

induction system.: Induction units use high-pressure primary air through nozzles, not two supply ducts.

dual-duct system.: Correct: a dual-duct system carries separate hot and cold supply ducts throughout the building to terminal mixing boxes at each zone.

Where the mixing happens identifies the system: at the zone box (dual-duct) or at the unit (multi-zone).

Answer: B

Clean the duct interior and leave the wrap as found: Interior cleaning does not stop condensation on bare exterior metal.

Restore the insulation and check for wet materials: Correct: missing insulation causes the condensation, so it must be restored, and wet ceiling and duct materials are checked for damage or growth (damaged insulation, water damage).

Treat the ceiling stains with an antimicrobial only: Treating the stain ignores the cause and any wet material.

Seal the duct seams from inside with a coating: Seam leakage is not the cause; the water forms on the uninsulated outside surface.

Missing duct insulation in humid spaces causes condensation and water damage; restore it and assess the wet materials.

Answer: A

Use a remote camera through a small, sealed port: Correct. Conduct visual inspections: a small, properly sealed inspection port with a remote camera shows the duct interior with minimal disturbance to the system and the ceiling.

Judge the interior from the face of the nearest diffuser: Diffuser faces collect dust from the room and do not show the condition of the duct interior.

Cut a full-size service opening in every branch duct: Excessive: large openings in every branch are for cleaning access, not a first inspection, and add unnecessary repair work.

Run the fan on high and watch for dust at the outlets: Running the system to dislodge debris pushes contamination into the occupied space and is not a visual inspection.

Use the least invasive access that still gives a direct view of the interior, and seal every opening made for inspection.

Answer: C

Run a NADCA Vacuum Test inside every supply outlet: Testing every outlet is impractical and does not show what the fan blows out at start-up.

Wait for occupant complaints over the next month: Relying on complaints is not verification.

Inspect the supply outlets for debris at start-up: Correct: watching outlets as the system restarts shows whether any loosened debris is still being discharged (system restart checks).

Measure the supply air temperature at one outlet: Temperature says nothing about debris discharge.

After restart, check the outlets for debris discharge before handing the system back.

Answer: A

Clean it, then repair or replace the torn areas: Correct: intact liner is cleaned gently, and small damaged areas are repaired or replaced per NAIMA guidance (restoring insulation).

Strip out all of the liner and leave bare metal: Removing intact liner is unnecessary and loses insulation and sound control.

Coat over the debris and tears without cleaning: Incorrect; coatings are never a substitute for cleaning.

Power wash the liner to remove loose fibers: Incorrect; water damages porous liner.

Restore insulation after cleaning: repair or replace damaged liner.

Answer: A

Use rated access doors so the shaft's fire rating is kept: Correct. access openings must not compromise fire-rated assemblies (NFPA 90A concept).

Remove a fire damper to create an access path: Incorrect; fire dampers must stay in place and working.

Cut through the shaft wall and patch it with plywood: Incorrect; a plywood patch does not keep the shaft's rating.

Leave the shaft opening uncovered for future service: Incorrect; an open rated shaft lets fire and smoke spread between floors.

Service access must preserve every fire-rated assembly.

Answer: B

Mix it stronger than the label rate for extra protection: Incorrect; using a product off-label is not allowed.

Confirm label use and registration, then get owner consent: Correct. products are used only as registered and labeled for HVAC use, with owner notification and consent.

Use any hospital disinfectant the crew has on hand: Incorrect; the product must be registered and labeled for use in HVAC systems.

Apply it while occupants are present so they can confirm it: Incorrect; occupants are notified and protected, not exposed.

Chemical use requires the right registered product, label directions, and the owner's informed consent.

Answer: B

High-speed rotary brushing with stiff nylon bristles: Incorrect; aggressive brushing erodes fibrous glass and releases fibers.

HEPA contact vacuuming with a soft-bristle brush: Correct. NAIMA AH-122 calls for gentle methods on fibrous glass so the surface is not damaged.

Power washing with a detergent solution: Incorrect; wetting porous liner damages it and can support microbial growth.

Steam cleaning the liner in place: Incorrect; steam wets porous insulation.

Fibrous glass is cleaned gently and dry; methods that erode or wet the surface are avoided.

Answer: B

Plan to clean only from registers where reach is easy: Cleaning only where convenient leaves parts of the system uncleaned.

Plan access and include it in the scope and price: Correct: the project assessment identifies access needs so the scope, schedule and price reflect them before work starts (perform project assessment).

Leave access planning to the crew on the first day: Unplanned access leads to delays, damage and disputes over scope.

Assume standard access and adjust the price afterward: Changing the price after the fact undermines a written scope the owner agreed to.

Plan access during the project assessment so the scope and price reflect the real work.

Answer: D

air sampling and surface culture swabs.: Microbial sampling is IEP work, not ACR cleanliness verification.

particle count and ATP swab tests.: These are not the verification methods named in ACR.

smoke pencil and duct leakage tests.: These assess airflow paths and leakage, not surface cleanliness.

Surface Comparison Test and NADCA Vacuum Test.: Correct: ACR names the Surface Comparison Test and the NADCA Vacuum Test, used with visual inspection, to verify that surfaces are clean.

ACR verification: visual inspection plus the Surface Comparison Test or the NADCA Vacuum Test.