Final answer:
After changing the pulley size on a blower motor from 3 1/4" to 4", it is essential to check the blower motor's speed, motor load, and belt tension to ensure they align with system specifications and do not exceed the motor's capacity.
Step-by-step explanation:
If you change the pulley on a blower motor from 3 1/4" to 4", the next thing you would need to check is the blower motor's speed and motor load. Increasing the pulley size will affect the fan speed, because a larger pulley will typically cause the blower to rotate slower but with more torque. It is important to check if the new speed meets the system requirements. Additionally, you should verify that the motor load does not exceed the motor's rated capacity, as a larger pulley may increase the load on the motor.
Besides speed and motor load, you might also want to reassess the belt tension since it can be affected by the change in pulley size. Ensure that the belt has the proper tension to avoid slippage or excessive wear. If the motor is part of an HVAC system, it is vital to check that the airflow still meets the system's needs after the pulley size change.