Weak Airflow from Vents
Quick Answer
Weak airflow is usually caused by a clogged air filter, blocked vents, or ductwork problems. Check and replace your filter first - this solves the problem in about 40% of cases. If airflow is still weak, you may have blower motor issues or duct leaks.
Safe Checks You Can Do
- 1Replace the air filter - A dirty filter restricts airflow significantly. Check monthly and replace every 1-3 months.
- 2Open all vents - Make sure supply and return vents throughout the home are fully open and unobstructed.
- 3Check accessible ductwork - Look in attic or basement for disconnected, crushed, or damaged ducts.
- 4Clean vent covers - Remove and wash dusty or dirty vent registers that may be restricting flow.
Likely Causes
- Clogged air filter
The most common cause. A dirty filter can reduce airflow by 50% or more.
- Ductwork leaks or damage
Holes, gaps, or disconnected ducts allow conditioned air to escape before reaching vents.
- Failing blower motor
A worn or failing blower can't push air effectively through the system.
- Frozen evaporator coil
Ice buildup on the coil blocks airflow. Often caused by low refrigerant or dirty filters.
- Undersized ductwork
Ducts that are too small for your system capacity can't deliver adequate airflow.
When to Call a Pro
- Changing the filter doesn't improve airflow
- You hear grinding, squealing, or rattling from the blower
- Some rooms have no airflow at all
- You see ice on the indoor coil or refrigerant lines
- Airflow has gradually decreased over time
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