When some vents in your house don’t blow hot air, the issue is usually caused by a blocked vent, a clogged air filter, or disconnected ductwork. Check if the vents are fully open, replace your air filter, and inspect your ducts for leaks or disconnections in your attic or crawlspace.
Blocked Vents
By far, the most common reason for uneven cooling is when some of your AC vents get blocked. This can happen if you place furniture too close to them. Or, it may happen because you've closed them on purpose. Unfortunately, blocked ducts can alter your AC's airflow and lead to hot and cold spots.
What Equipment Do I Need to Clean My Ducts?
When your heat is on but cold air comes from your vents, it usually means the system's blower fan is running, but the heating element isn't igniting or producing warmth. Check your thermostat fan setting (should be "Auto"), replace any clogged filters, and ensure your gas or power supply is fully on.
If your AC is only blowing air from some vents, the most likely culprit is either blocked airflow or a disconnected duct.
If your system does not have enough refrigerant it is possible that a low refrigerant charge could be the cause. A low a/c system cause one half of your evaporator to work and the other half not to cool. This will cause the air coming out of some ducts to feel cool and the air out of other ducts to feel warm.
Check for blocked air ducts by testing the airflow at each vent while the HVAC system is running. Look for inconsistent room temperatures, excessive dust accumulation, whistling noises, or a sudden spike in energy bills.
A blocked furnace exhaust is a serious safety hazard that can cause carbon monoxide to spill into your home. Here is how to safely check for a blockage:
In winter, the air coming out of your vents should typically be between 85°F and 140°F. Gas furnaces generally blow hotter air (120°F–140°F), while heat pumps operate at lower temperatures, typically 85°F–110°F. A good rule of thumb is that the air should feel significantly warmer than your body temperature, which is why heat pump air can sometimes feel cool to the touch (around 90°F–95°F).
Here are key signs that indicate your heater core may be failing:
You can periodically clean your air ducts and vents yourself, as long as the air ducts do not have mold, and maybe only a little dust and dirt. You can use a brush and a shop vacuum to clean them out. You may have to unscrew the grills if the air ducts are dusty so as to run the vacuum along the inside of your vents.
Common Symptoms of a Clogged Drain Vent Pipe
If the job is too dangerous, hire a pro to take care of it. If you decide to hire a licensed plumber near you to handle the fix, you can expect to pay between $150 and $200 for this service, although it could cost more depending on the severity of the problem. To unclog a plumbing vent, you first need to locate it.
Issues with the pilot light, high limit switch, blocked burners, leaky ductwork, electrical problems, and blower motor failures are common reasons for HVAC systems blowing cold air. These problems often require professional maintenance and repairs.
Your first indication that you need furnace repair might be:
How Do I Stop Cold Air from Coming Through my Range Hood Vent?
Is 72 a good temperature for heat in the winter? While slightly higher than the typical energy-saving range of 68°F–70°F, 72°F still offers a reasonable balance between comfort and efficiency.
*Any reduction in the temperature of your home from a trickle vent is very marginal and unnoticeable. If you are concerned about your home feeling cold, it is likely something else and not your trickle vents causing the issue. Take a look at our 5 simple steps to make sure your home is winter ready.
Furnaces can shut off entirely because these vents are blocked with snow or ice – this is simply a safety mechanism. Without the proper ventilation, carbon monoxide can build up inside your home. The blockage of your vents will also decrease your energy.
The heat exchanger is often considered the most costly part of a furnace to repair or replace. It is a critical component that transfers heat from the combustion process to the air that circulates throughout your home. Over time, heat exchangers can crack due to the constant heating and cooling cycles they undergo.
A clogged vent pipe rarely looks different from a functional one on the outside, but it severely disrupts your plumbing. Inside your home, it looks like bubbling toilets, sluggish sinks, and foul-smelling drains. On your roof, it may look like an open pipe stuffed with debris.
Signs of a blocked or narrowed duct
Neglecting air duct cleaning decreases your indoor air quality and lowers HVAC efficiency. Dust, pet dander, mold, and even pests accumulate inside, eventually causing respiratory issues, foul odors, higher energy bills, and early wear on your HVAC system.
While homeowners insurance does cover HVAC systems in the event of a disaster like a fire or a storm, it will not cover breakdowns due to ordinary wear and tear. So if you're wondering, does homeowners insurance cover HVAC issues like ductwork problems over time? —the answer is no.