Short answer: Many people are inclined to take the temperature and humidity attributes of their home as a default, immutable fact of construction. However, more often, poor air ventilation due to leaks and insufficient airflow through the building’s ductwork can be the primary reason behind such environmental discomfort. This can lead to differential temperature zones, condensation, and also negatively impact system efficiency. Mold, mildew, unusual odor, and even dirt, debris or dust from your ductwork could also suggest a ventilation issue of this nature. You needn’t wait till your home or business is scarcely protected from the elements or has a peculiar musty odor before you look into an air duct inspection or repair job, as long as you can look for these archetypal signs.
This is a common question among homeowners, especially those who have a basement or an attic, both being areas prone to air duct problems. Noticing a leak can be as simple as feeling a draft in the air or as complicated as soaring energy bills. Understanding the way your air conditioner works and the issues that may occur is fundamental in noticing a sign of an issue.
Do you notice unwanted smells or other indications of fumes near utilities like your drying machine or fireplace?
How to perform a simple DIY duct leak test
This low-cost test helps you find obvious leaks before calling a pro. It is safe for most homeowners and uses items you already have.
- What you need - an incandescent or stick-on thermometer, a piece of tissue or ribbon, and a flashlight.
- Step 1 - Turn off all exhaust fans and combustion appliances. Close doors to isolate the area.
- Step 2 - Turn on the HVAC fan only, then hold a tissue to the return grille. If air is being drawn in strongly from other rooms or gaps, you may feel tugging at cracks or exterior openings.
- Step 3 - Walk the duct runs in the attic or garage with a flashlight while the fan runs. Look for dust streaks, gaps at seams, or insulation pulled away from the duct.
- Step 4 - Record rooms with weak supply airflow using a thermometer for later comparison.
Safety note - do not block combustion appliance vents or perform tests that could cause negative pressure if you have gas appliances. If you suspect dangerous fumes or carbon monoxide, evacuate and call professionals immediately.
If you want a full diagnostic that measures total leakage and energy impact, ask about a duct blaster test when you schedule a professional inspection.
Utilities that require ventilation links to the exterior of the home need this ventilation system, not just to be able to function cleanly, but for the sake of the residents’ health, too. Homeowners should regularly inspect these areas. One common source of issues to look out for involves improper insulation or seal, leading to toxic air not being transported outside or indoor air being wasted due to leakage.
Are some rooms noticeably harder to keep cool or warm?
Uneven temperatures are one of the most common, easy-to-spot signs of leaking or poorly sized ductwork. In Las Vegas summers, rooms that never seem to cool can drive your AC to run longer and raise bills quickly.
Quick diagnosis steps you can do today
- Check vent airflow - turn your system on, hold a tissue or lightweight ribbon in front of each supply vent. Strong airflow means the duct to that room is likely OK. If it barely moves, the duct could be blocked, disconnected, or leaking.
- Measure temperature differential - place cheap digital thermometers in the problem room and a central room for 15 to 30 minutes. A steady 4°F to 6°F difference suggests restricted airflow or leaks.
- Inspect accessible ducts - in the attic, garage, or basement, look for disconnected seams, crushed flex duct, or fallen insulation. In neighborhoods like Summerlin and Henderson, many older tract homes have ducts routed through unconditioned attics where connections loosen.
- Try a simple supply/return swap test - close bedroom doors, open a window slightly, then check if closing the door changes airflow at the vent. Large changes can indicate pressure imbalance from leaks.
Expert tip - if your AC runs continuously in Las Vegas heat and some rooms still stay warm, it is often a duct problem rather than the outdoor unit. For fast service and diagnosis during peak heat, see our Same Day AC Repair Las Vegas guide.
- If you find a loose connection or torn duct, avoid using duct tape as a permanent fix. Use foil tape or have a technician reseal and re-insulate the run.
Do some rooms of your home seem too stuffy?
When to call a pro - checklist and expected next steps
Some fixes are best left to licensed technicians. Use this checklist to decide when to call The Cooling Company.
- Call a pro if you find mold, persistent musty smells, disconnected duct sections, or if DIY sealing does not improve airflow.
- If you notice high energy bills, frequent cycling of the system, or soot near vents, schedule a diagnostic.
- Expect a technician to perform a visual inspection, check static pressure and airflow, and offer a blower door or duct pressure test.
- After diagnosis, common professional services include resealing ducts, adding insulation, replacing damaged sections, or full duct replacement.
Typical outcomes and links
- Minor sealing and insulation - usually a same-day fix.
- Major duct replacement - estimate and planning required; see our Air Duct Replacement Cost guide for what to expect.
- Emergency repairs in extreme heat - we offer expedited visits; learn more at our Same Day AC Repair Las Vegas page.
For a detailed cost breakdown, see our HVAC pricing guide.
The Cooling Company’s licensed technicians explain findings, show before-and-after photos, and provide transparent quotes so you can decide the best path forward.
Temperature isn’t the only thing impacted by airflow. Stale air, besides being unhygienic and a potent allergy irritant, can also signal that nearby ventilation isn't functioning optimally. A well-ventilated room with good airflow should feel ‘fresh’ and brisk every hour of the day. If you notice the air in some areas seems stale, the problem could be with your air conditioner in the attic or basement.
Does your ventilation system show signs of damage or substandard materials used?
Damaged vents, worn-out insulation, or insufficient sealing are obvious signs of something wrong. But beware – duct tape isn't a long-lasting solution and these cheap substitutes often degrade over time. Professional work is needed to ensure the system is back to its optimal function.
Do you see an unusual amount of dust, debris, or signs of mildew and mold in your home?
Excess dust or mold often means your ducts are drawing air from unconditioned spaces like crawlspaces, attics, or wall cavities. In Las Vegas, seasonal dust storms and monsoon humidity spikes can make these symptoms worse.
What is happening
- Leaks in return ducts can pull in dirt and allergens from dusty attics or garages.
- Moisture entry at seams or uninsulated ducts can create cooler surfaces where condensation forms, leading to mildew.
- High indoor dust despite frequent cleaning usually points to infiltration through leaks, not just surface dust.
Simple homeowner checklist
- Change filters monthly during heavy-use months, like July and August in Las Vegas. Use a filter with an appropriate MERV rating for your system.
- Inspect visible returns and registers for gaps - press around the grille; if air is felt leaking out, the return may be pulling in dust from hidden spaces.
- Look in the attic or crawlspace for dusty swirls near duct seams, disconnected boots, or missing insulation.
Local tip - desert dust is very fine and will travel through even small leaks. During summer and dust events, replace filters sooner and consider sealing attic access with weatherstripping.
If you find mold or suspect contamination inside ducts, stop attempting DIY cleaning beyond filter changes. Professional inspection and possible duct repair or replacement is safer. Learn more about typical costs for duct replacement.
Are your utility bills higher than normal or expected?
Las Vegas climate tips that affect ducts and indoor air
Las Vegas has extremes that change how ducts perform. Use these seasonal tips to protect your system and comfort.
- Summer - intense heat increases pressure on the cooling system. Ensure ducts in unconditioned attics are insulated and sealed to prevent heat gain.
- Monsoon and humidity spikes - watch for condensation on ducts and fast mold growth in shaded, damp spaces. Seal and insulate to control moisture.
- Dust storm season - fine desert dust clogs filters and infiltrates through leaks. Replace filters more often, and inspect returns after major storms.
- Older homes in older neighborhoods - many have ducts routed through unconditioned crawlspaces or attics. Consider a professional duct audit if your home is older than 20 years.
For homeowners considering system upgrades, the right ductwork sizing and sealing can change estimated system needs. Learn how ductwork affects overall HVAC installation costs.
Leaking or disconnected ducts are expensive. The U.S. Department of Energy estimates that 20% or more of the air that moves through duct systems can be lost to leaks, holes, and poorly connected ducts in many homes. In Las Vegas, where cooling runs dominate the season, this lost conditioned air translates directly to higher bills.
How to estimate your loss
- Compare month-to-month energy use for the same season over the last 2 to 3 years. A sudden increase without rate changes or more occupants points to system inefficiency.
- Rough calculation - if your cooling account shows a 20% increase during peak months, and your AC usually costs $150 monthly in summer, leaks could be costing roughly $30 or more each month.
Action steps to reduce costs
- Seal visible seams with foil HVAC tape or call a tech to mastic-seal hard-to-reach joints.
- Insulate ducts in unconditioned spaces to reduce heat gain or loss.
- Schedule a professional duct evaluation and blower door or duct pressure test to quantify leaks.
The Cooling Company recommends regular duct inspections and offers fast diagnostics. If your bills spike suddenly during extreme Las Vegas heat, consider scheduling a service visit or see our heating and cooling emergency tips.
Related service: Need ductwork service in Las Vegas? Explore our AC repair and AC maintenance services for Las Vegas homeowners.
Related reading: ductwork troubleshooting, and how to check air ducts for leaks.
Need HVAC Service in Las Vegas?
The Cooling Company provides expert HVAC service throughout Las Vegas, Henderson, and North Las Vegas. Our licensed technicians deliver honest assessments, upfront pricing, and reliable results.
Call (702) 567-0707 or visit ductwork, duct repair, duct cleaning, or AC repair for details.