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Question 341. Which sides of a coil should be accessed for cleaning

1. Top and bottom only
2. Drain side only
3. Upstream and downstream sides
4. Exterior side only

Correct Answer: 3. Upstream and downstream sides

Explanation:

NADCA guidance states that both the upstream and downstream sides of each coil section should be accessed when coil cleaning is performed. Contamination can collect throughout the coil depth, so cleaning only one exposed face may leave substantial debris behind. Complete access allows the technician to inspect and clean the coil more effectively. When both sides cannot be accessed, additional measures such as removal or replacement may be necessary. The goal is to achieve effective cleaning while preserving the coil surface and fins and maintaining normal airflow and heat transfer performance.

Question 342. What may be required if both coil sides cannot be accessed

1. Removal or replacement
2. Higher fan speed
3. Filter removal
4. Duct enlargement

Correct Answer: 1. Removal or replacement

Explanation:

When both sides of a coil cannot be properly accessed for cleaning, NADCA guidance indicates that removal or replacement may be required. Coil contamination can extend into areas that cannot be reached effectively from one side. Attempting incomplete cleaning may leave debris inside the coil and prevent the component from reaching the required cleanliness level. Technicians should evaluate accessibility, coil condition, cleaning effectiveness, and manufacturer requirements before deciding how to proceed. The solution should allow the coil to be cleaned adequately without causing physical damage to fins, tubes, or surrounding HVAC components.

Question 343. What should be cleaned and flushed during coil cleaning

1. Supply registers only
2. Fan belts only
3. Filter racks only
4. Condensate pan and drain line

Correct Answer: 4. Condensate pan and drain line

Explanation:

NADCA guidance requires the condensate drain pan and drain line to be cleaned and flushed when the relevant coil cleaning procedure is performed. Dirt, biological material, and other debris can collect in these moisture handling components and interfere with drainage. Leaving the drain system dirty after cleaning the coil can allow standing water or contamination to remain inside the unit. The drain pan should also be inspected for condition and proper drainage so moisture created during normal HVAC operation can leave the equipment instead of accumulating inside it.

Question 344. When should condensate drainage be tested

1. Only during installation
2. Before and after cleaning
3. Only after filter replacement
4. Only when leakage occurs

Correct Answer: 2. Before and after cleaning

Explanation:

NADCA guidance states that the condensate drain pan should be inspected and tested to verify drainage both before and after cleaning. The initial check helps identify an existing drainage problem before work begins. The post cleaning test confirms that cleaning procedures did not create a blockage and that the pan and drain line are functioning correctly. Proper drainage is essential because standing water can damage equipment and contribute to unwanted microbial conditions. Testing before and after cleaning provides a simple quality control step for moisture management.

Question 345. Which method belongs to Type 1 open air plenum cleaning

1. HEPA filtered contact vacuuming
2. Pressure washing
3. Steam cleaning
4. Chemical washing

Correct Answer: 1. HEPA filtered contact vacuuming

Explanation:

NADCA’s open air plenum guidance identifies HEPA filtered contact vacuuming as a Type 1 dry cleaning method. Other Type 1 approaches can include dry dusting, brushing, wiping, agitation, blasting, and compressed air washing performed with appropriate negative air control. These methods are designed to remove contamination without introducing liquid into the space. Open air plenums can contain many building systems and potentially hazardous materials, so the selected cleaning method should be based on the actual surfaces, contamination, access conditions, and project hazards present in the plenum.

Question 346. Which method belongs to Type 2 open air plenum cleaning

1. Dry brushing only
2. HEPA vacuuming only
3. Steam cleaning
4. Dry air washing only

Correct Answer: 3. Steam cleaning

Explanation:

Steam cleaning is listed by NADCA as a Type 2 wet cleaning method for open air plenums. Other Type 2 methods can include wet wiping, water washing, pressure washing, and chemical cleaning. Wet methods require careful planning because plenums may contain electrical wiring, telecommunications equipment, fire protection components, insulation, and other materials that can be damaged by moisture. The technician should determine whether the surface and surrounding building systems can tolerate the selected process and should establish suitable water collection, containment, drying, and safety procedures before work starts.

Question 347. What minimum cleanliness level should an open air plenum normally achieve

1. Completely sterile
2. Visibly clean
3. Newly coated
4. Completely dry only

Correct Answer: 2. Visibly clean

Explanation:

NADCA’s open air plenum guidance states that these spaces should be cleaned at minimum to the visibly clean level unless another cleanliness requirement has been agreed upon in the project scope. Verification provides evidence that the cleaning process achieved the intended result. Additional forms of cleanliness verification can also be used when they are specified. The goal is not simply to spend a certain amount of time cleaning. The contractor should produce a documented outcome that meets the defined scope while protecting the many building systems that can be located inside an open plenum.

Question 348. Why can open air plenums be difficult to clean safely

1. They contain refrigerant only
2. They are always sealed
3. They contain no building equipment
4. They may contain many systems and hazardous materials

Correct Answer: 4. They may contain many systems and hazardous materials

Explanation:

Open air plenums can contain mechanical equipment, electrical systems, plumbing, gas piping, fire protection, telecommunications, and other building infrastructure. NADCA also notes that these typically unfiltered areas can contain dust, debris, asbestos, lead, animal waste, microbial contamination, and various hazardous materials. These conditions make assessment particularly important before cleaning begins. Technicians may need specialized safety procedures, testing, additional training, or help from qualified professionals. An open plenum should never be approached as though it were simply a large section of ordinary sheet metal ductwork.

Question 349. What is a major contamination concern in unfiltered plenums

1. Only clean outdoor air
2. Refrigerant leakage only
3. Accumulated dust and debris
4. Potable water only

Correct Answer: 3. Accumulated dust and debris

Explanation:

Open air plenums are often unfiltered spaces, which means dust, dirt, debris, and other contaminants can accumulate over time. Air moving through these spaces can then transport contamination toward occupied areas or HVAC equipment. NADCA notes that contaminants in plenums may range from ordinary nuisance dust to more serious hazards such as asbestos, lead, microbial contamination, animal byproducts, and chemicals. Periodic inspection is therefore important so the condition of the plenum can be assessed and an appropriate cleaning or remediation approach selected.

Question 350. What distinguishes an open air plenum from a plenum box

1. It is a nonducted building space used for airflow
2. It always contains a cooling coil
3. It is always outdoors
4. It stores refrigerant

Correct Answer: 1. It is a nonducted building space used for airflow

Explanation:

NADCA distinguishes an open air plenum from a plenum box. An open air plenum is an open building space or void intended to provide an airflow pathway, such as a ceiling space, wall cavity, or area beneath a raised floor. A plenum box is a constructed HVAC component connected to ductwork near an air handling unit or distribution system. Confusing the two can lead to poor project planning because an open plenum can contain many unrelated building systems and materials requiring additional assessment and protection during cleaning.

Question 351. Why should acid coil cleaners be used with extreme caution indoors

1. They always damage filters
2. They increase fan speed
3. They reduce duct size
4. They can release hazardous fumes

Correct Answer: 4. They can release hazardous fumes

Explanation:

NADCA chemical guidance warns that acid cleaners can release unpleasant and potentially dangerous fumes and should not be used indoors under inappropriate conditions. Coil cleaning chemicals should be selected according to material compatibility, manufacturer instructions, ventilation requirements, and the actual cleaning need. NADCA also recommends using solutions as close to neutral as practical when suitable. Strong chemistry does not automatically produce better cleaning and may damage equipment or expose workers and occupants unnecessarily. Mechanical cleaning and proper rinsing remain important parts of effective coil maintenance.

Question 352. What source should a technician follow for chemical dilution

1. Customer preference
2. Product label directions
3. Filter manufacturer only
4. Building drawings

Correct Answer: 2. Product label directions

Explanation:

Chemical manufacturers provide specific dilution and application instructions based on how their products are designed and tested. NADCA advises users to follow the directions printed on the product container label. Using an incorrect concentration can reduce cleaning effectiveness, damage HVAC materials, increase chemical emissions, or expose workers and occupants to unnecessary risk. The technician should also review safety information and confirm that the product is appropriate for the intended HVAC application. Chemical use should be controlled and purposeful rather than based on habit or personal preference.

Question 353. What should follow dry coil cleaning if significant contamination remains

1. Consider appropriate wet cleaning
2. Reenergize immediately
3. Ignore remaining debris
4. Paint the coil

Correct Answer: 1. Consider appropriate wet cleaning

Explanation:

NADCA coil cleaning guidance describes dry cleaning as an initial method for physically removing loose dust and dirt. After dry cleaning, the coil should be visually inspected again. If substantial contamination remains or suspected microbial growth is present, an appropriate wet cleaning process may be considered. Wet cleaning can use a compatible chemical cleaner and water, but the technician must control moisture, protect nearby components, and follow product instructions. The cleaning method should progress according to actual coil condition rather than assuming that every dirty coil needs the strongest process immediately.

Question 354. What tool may help straighten or clean delicate coil fins

1. Pipe wrench
2. Metal chisel
3. Plastic coil comb
4. Roofing hammer

Correct Answer: 3. Plastic coil comb

Explanation:

NADCA coil cleaning guidance notes that a plastic coil comb can be used as part of dry coil cleaning while debris is being vacuumed. A suitable coil comb can help work through fin areas without using excessively aggressive tools. Coil fins are delicate and can bend easily, so cleaning techniques should preserve airflow passages and heat transfer surfaces. Technicians should avoid unnecessary force and should follow manufacturer recommendations when available. Coil cleaning should improve cleanliness without causing erosion, bending, or other physical damage to the component.

Question 355. Why is local negative air useful during dry coil cleaning

1. It changes refrigerant pressure
2. It cools the building
3. It increases coil temperature
4. It helps capture loosened dust

Correct Answer: 4. It helps capture loosened dust

Explanation:

Using local negative air near the coil helps capture dust and dirt as the technician disturbs and removes it. Without effective collection, dry brushing or vacuum assisted agitation can allow particulate material to spread into adjacent air handling components or the surrounding work area. NADCA coil cleaning guidance recommends capturing dust locally as work proceeds. This follows the broader source removal principle of loosening contamination while controlling and collecting it. Local negative air is therefore both a cleaning effectiveness measure and a contamination control measure.

Question 356. Why should a coil cleaner match the coil material

1. To prevent corrosion or surface damage
2. To increase room humidity
3. To reduce duct length
4. To change filter efficiency

Correct Answer: 1. To prevent corrosion or surface damage

Explanation:

Evaporator and condenser coils can be made from different metals and may also have specialized coatings. A chemical that is suitable for one material can damage another through corrosion, erosion, or coating deterioration. NADCA guidance therefore emphasizes following manufacturer recommendations and using cleaning solutions that are compatible with the coil surface. The preferred product should remove contamination while preserving fins and other surfaces. Material compatibility is a fundamental part of cleaning method selection because successful cleaning should never shorten equipment life by damaging the component being cleaned.

Question 357. What should an ASCS do before entering a potentially hazardous plenum

1. Increase system airflow
2. Assess hazards and required training
3. Remove all protective equipment
4. Begin cleaning immediately

Correct Answer: 2. Assess hazards and required training

Explanation:

Open air plenums can contain electrical hazards, confined spaces, fall hazards, hazardous materials, microbial contamination, gas piping, and many other risks. NADCA emphasizes evaluating the environment before cleaning and determining whether specialized training or controls are required. Depending on the project, technicians may need respiratory protection, confined space procedures, fall protection, air monitoring, lockout procedures, or assistance from qualified specialists. Entering first and evaluating hazards afterward is not acceptable risk management. The work plan should be based on conditions identified before disturbance begins.

Question 358. Why may plenums need periodic inspection even without complaints

1. They always contain refrigerant
2. They never collect dust
3. Contamination can accumulate over time
4. They automatically clean themselves

Correct Answer: 3. Contamination can accumulate over time

Explanation:

NADCA recommends periodic inspection and cleaning of open air plenums because airflow through these typically unfiltered areas can contribute to accumulation of dust, debris, odors, condensation, microbial growth, and other contamination. Problems can develop even before occupants report obvious symptoms or visible dirt appears in occupied spaces. Routine inspection allows building owners and technicians to identify conditions earlier and determine whether cleaning or another corrective action is appropriate. The actual frequency should reflect building conditions, plenum use, contamination sources, and operating history.

Question 359. What should a technician do when an open plenum contains suspect asbestos

1. Stop disturbance and seek qualified guidance
2. Vacuum it without assessment
3. Use compressed air immediately
4. Wet clean everything

Correct Answer: 1. Stop disturbance and seek qualified guidance

Explanation:

Suspect asbestos should not be disturbed through ordinary HVAC cleaning methods. Open air plenums can contain asbestos containing materials along with lead, microbial contamination, animal waste, and other hazards. When such material is suspected, the technician should stop disturbance and follow applicable regulations and professional guidance. Specialized testing, containment, licensing, or abatement procedures may be required. An ASCS must recognize the limits of routine cleaning work and avoid creating airborne exposure by brushing, blowing, or vacuuming suspect material without the proper hazard assessment and controls.

Question 360. What should determine the final cleaning method for an open air plenum

1. One standard method for every plenum
2. Actual materials contamination and hazards
3. Customer age
4. Building exterior color

Correct Answer: 2. Actual materials contamination and hazards

Explanation:

Open air plenums vary significantly in construction, use, contamination, access, and the building systems they contain. NADCA guidance identifies both dry and wet cleaning methods, but the selected method should reflect the actual surfaces, contaminants, hazards, and project requirements. A technique suitable for concrete or metal may be inappropriate around electrical equipment, insulation, hazardous materials, or sensitive building systems. Proper assessment therefore comes before method selection. The goal is to reach the agreed cleanliness level while controlling hazards and avoiding damage to the plenum or surrounding building infrastructure.