1998 Silverado Z71

[Jdan1930]

Just put a new AC blower motor in, bought it from NAPA.   Everything works great except when I turn it on the highest speed. It vibrates the whole dash and is loud. Was wondering if I took the gasket off the original blower motor and put it on the new one would this help? Do you think something could be wrong with this blower motor?

[Jsdirt]

If it came with the squirrel-cage fan, it may be bent,  or unbalanced. Usually there's a small, clip-on weight on them for balancing - that could be missing. If this is the case, return it for another one.

 

If you had to remove the fan from the old unit, and transfer it to the new unit, you may have tweaked the fan during the installation onto the new motor shaft. You could try to straighten it, or attempt to balance it somehow. I think blower motors have too much resistance to movement, so you'd have to remove the fan again and rig something up in a vise, and stick some type of weight on there until the fan stops falling to the heavy side.

 

Would certainly be much easier to just replace the plastic fan at that stage ...

Edited June 30, 2019 by Jsdirt

[Colossus]

yup, defenitly sounds like an out of balance hampster running wheel fan.