Smelling smoke coming from your HVAC system can be alarming. After all, it is natural to assume that smoke indicates a house fire. Fortunately, smoky odors wafting from your heating and cooling system are not always symptomatic of an impending home emergency. For example, you may encounter a slightly singed or burning smell when you turn on your HVAC unit for the first time in the season after months of disuse. During any dormant period, your HVAC system’s interior may accumulate dust in its ducts or on heating and cooling elements. As the system gears up for use, the dust layer produces a scorched smell that dissipates quickly. However, sometimes, HVAC units produce persistent burning smells that require professional troubleshooting. A look at the most common reasons your HVAC system may smell like smoke can guide you in resolving the unwanted issue.
Dirty Filter or Vents
Dirty or clogged filters are among the top causes of smoky odors from your heating and cooling network. The purpose of an HVAC air filter is to trap dirt, dust, lint, pet hair, and other airborne debris. This prevents excessive contaminants from damaging your HVAC units and can also help keep indoor air quality breathable and healthy. Over time, however, the accumulation of trapped pollutants can obstruct the filter and restrict airflow. This causes a smoky smell in two ways. First, dirt clogs and other particles can harbor mold that produces an acrid, musky odor when exposed to heat from your HVAC unit. Second, obstructed filters mean your system has to work harder to produce sufficient airflow. This may cause components to overwork to push air through the system, and the overheating can produce a burning smell.
To prevent both problems from occurring, experts recommended changing your HVAC filter at least once every three months. You can also speak to a technician about installing filters with the right minimum efficient reporting value (MERV) rating. A technician may also help you upgrade to a high-efficiency particulate air (HEPA) filter that helps remove up to 99.97% of airborne particles with a size of 0.3 microns (µm).
Overheated Motor or Fan
An overheated HVAC motor is another leading cause of unpleasant smoke odors. HVAC motors or fans may overheat from friction due to insufficient lubricant. Excessive layers of dirt or debris that are thick enough to block the fan may also cause overheating. During particularly hot and humid weather, HVAC motors may struggle to keep up with the system’s intense demands. This extra work can strain and overheat your motor within hours. Homeowners can help reduce the risk of an overheating motor by keeping up with recommended maintenance sessions. During routine maintenance, a technician can lubricate moving parts and service the motor so that it can work smoothly and withstand extreme temperatures.
Overheated Wiring
Overheated wiring can also produce a smoky smell. Wiring within HVAC systems often has plastic coverings that may loosen over time. The loose plastic can then begin to melt due to the concentration of heat within your system and emit a burning smell. Other sources of smoke can include wires loosened from degraded insulation or exposed live wires from normal wear and tear. Any problem with detached wiring requires professional repairs to prevent significant damage to your HVAC unit and to reduce the risk of safety hazards within your household.
Electrical Problems
Electrical shorts can emit sparks that melt insulators and produce a burnt smell. These electrical shorts occur when an electrical current diverts from its intended path and distributes power in an unfavorable area. Other electrical components such as the circuit board can overheat due to faulty connections or extensive use. This overheating can then result in a scorched smell similar to pungent smoke. Homeowners describe the smell as “fishy” or similar to melting plastic. If you suspect a faulty electrical component, reach out to a professional as soon as possible. A technician can evaluate your system to see if the electrical problem is as simple as a tripped circuit breaker or something more serious like an arc fault that can cause an electrical fire.
Mechanical Problems
HVAC systems contain various mechanical parts such as conveyor belts, blowers, and bearings. Over time, these mechanical parts can wear down due to abrasion or friction. Degraded mechanical parts can emit smoky odors due to malfunctions and breakdowns or from constant chafing during normal operation. In addition to unpleasant odors, mechanical issues may often include the telltale signs of loud and unusual noises. For example, worn-out metal bearings may produce squealing noises as they strain within the system. A torn HVAC belt can emit screeching noises, and the friction is usually enough to emit a burnt rubber smell. If you notice any of these signs, contact an HVAC technician for repair or replacement of mechanical parts.
Oil or Gas Leaks
For homes with oil-based or gas-based HVAC, smoky smells can also indicate inefficient fuel burning. Oil or gas leaks can result from malfunctioning burners, obstructed intake or exhaust vents, clogged nozzles, or problems with the fuel supply. Homeowners often describe gas leaks as having a sulfuric or “rotten egg” smell. You may also notice other signs such as stuffy air quality or an HVAC burner that produces an unusual yellow pilot light. If you suspect a gas leak, it is important to evacuate the home and contact an HVAC professional immediately. A trained expert can identify the source of insufficient combustion and repair the issue before the harmful fumes impact the health of your family.
Broken or Damaged Capacitor
The HVAC capacitor is a tubular component in your HVAC system’s outdoor condensing unit. This element houses or stores the energy required to initiate your system’s cooling cycle. The capacitor does its job by producing a small electrical jolt when it is time to start a new cycle. Unfortunately, the capacitor can break down due to tripped electrical circuits, sudden power surges, or general wear and tear. If the capacitor malfunctions or breaks, the motor may overheat and produce a dreaded smoke smell. A bad capacitor constitutes a safety hazard, so it is important to turn off your system if you see or smell smoke coming from your outdoor condenser unit. Reach out to a technician for assistance.
Dirty Coils
HVAC units contain evaporator and condenser coils that work together to exchange indoor and outdoor air. This helps your home maintain comfortable conditions. Unfortunately, coils covered in dirt or debris can emit a burning smell as your HVAC unit heats up during operation. By scheduling regular maintenance or annual tune-ups, you can ensure that your coils remain clean and eliminate this source of unpleasant odor.
Old Age
Components of your overall HVAC system can also produce smoke smells as a sign of old age. HVAC units such as furnaces, air conditioners, or heat pumps can all give off bad odors as they strain to perform against challenges like overheating or depreciated parts. Along with the burning smell, you may also notice that the HVAC unit has trouble powering on, shuts off randomly, or fails to produce heated or cooled air. A technician can evaluate units within your system and determine whether it’s time for an upgrade or replacement.
Contact Us Today
Smoky odors can signify that a problem with your heating and cooling system needs professional intervention. While unpleasant smells blowing out of your HVAC system may be distressing, there is no need to panic. Specialty Heating & Cooling LLC offers HVAC services for homes in Tigard, OR and surrounding areas. Our technicians can install, troubleshoot, or repair HVAC units like furnaces, air conditioners, or heat pumps. We also work with heat pumps and can examine your ducts or help you upgrade to a ductless system. Our technicians are experts in indoor air quality and can help you eliminate any smoky odors so that your house smells like new again. No matter the issue, we can help. Contact Specialty Heating & Cooling LLC today for all HVAC needs.
