Could a nosey blower motor slow down your ac unit and stop your defroster for a honda civic?

Could a nosey blower motor slow down your ac unit and stop your defroster for a honda civic? - 1

Absolutely. Replace it.

Why is it noisy ( note correct spelling )?

If it is noisy because a leaf or some other small foreign object is rubbing against the fan blades, the noise isn't really harming the motor.

But if the noise is a result of the motor being on its last legs, then yes, it can definitely have an affect on the A/C and defroster.