Low Airflow in Central HVAC System Despite Clean Filters – What Else to Check?

[Brotherfiltration]

Hi everyone,
I’m hoping to get some advice on a central HVAC system airflow issue.

The system is cooling/heating, but airflow from the vents feels noticeably weak compared to before. I’ve already checked and replaced the air filters, made sure vents are fully open, and confirmed nothing is blocking the returns. The blower seems to be running, but the air volume still feels low.

Before calling a technician, I wanted to ask:

• What are the most common causes of low airflow besides dirty filters?
• Could this be related to duct issues, blower motor problems, or something like a partially blocked coil?
• Are there any basic checks a homeowner can safely do before scheduling service?

Any guidance or troubleshooting steps would be appreciated.
Thanks in advance!

 

[Fitter30]

Blower speed might be raised? Take a pic of the wiring diagram with brand and model number. With furnace powered off. Look at the blower wheel with a good flash lite or drop lite. Is it summer in China? Look at the blower wheel the cups on the blades. Is there more dirt than dust? Even with changing filters religiously they get dirty. Blower wheel is easily cleaned. Take pics with ur phone. Usually two screws can pull it and a plug to unwire motor. Pull motor can wash it out with dish detergent and hose. Let dry put it back together. While it's drying if it's not 90+% can look between furnace sections and look at to coil with a good lite. If not could needs to be pulled if possible depend on the lines. Puller set screws bite into the hub. With a file clean up the flat shaft.
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