What causes whaling sound after ac replacement

Hi, I'm one of the auto experts on RepairPal's Car Genius team! If you are hearing a noise from behind the glove compartment, you are likely hearing the blower motor. Either something is hitting it, or the bearings in it are failing. You mentioned that you had AC replaced, however this could mean several different things. Depending on what components were replaced this may or may not be a potential warranty issue. The fact that it started after the repair may be related or could be coincidental. Either way, it is worth having the shop that initially did the work check it out and see what is going on. If you need any further advice or would like help finding a trusted RepairPal shop in your area or even getting an appointment booked, please feel free to call us at 877-913-1554 or check out https://repairpal.com/certified