Furnace runs but the blower airflow is weak from the registers.

Safety first: Turn off power before accessing blower or coil compartments.

• Replace filter: Install a new, properly sized filter.
• Inspect evaporator coil: If accessible, remove the coil access panel and visually inspect the coil fins for dust and debris. A heavily clogged coil needs professional cleaning.
• Check blower speed tap (PSC motors): Verify that the correct speed tap is connected for heating as per the Carrier wiring diagram. Do not change speeds without understanding airflow requirements.
• Inspect ducts: Look for crushed flex duct or closed dampers that may be restricting flow.

If airflow remains weak, a technician should measure static pressure and evaluate the blower motor.