Q: My heater makes a really loud noise when its on.

The level of refrigerant in the air conditioning system would not affect the noise level of the blower motor. If you replaced the motor with an aftermarket (non OEM) motor that could create an issue in terms of the quality of the motor and noise level. Check the motor mounts, and the blower wheel. To gauge whether the noise is motor related, mount related, or wheel related, you can try running the motor alone in free air. If the noise is from the blower wheel, unless there is an obvious defect you are more or less stuck with it unless you want to buy another OEM wheel to see if that makes a difference. If the noise originates in the motor, obviously return the motor to the vendor for refund. If you desire that this problem be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a blower noise diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.