This is typical of worn bearings in the fan motor. The proof would be found by the noise changing when you select different fan speeds. Also, the noise often diminishes a few minutes after the motor warms up. The only fix is a new fan motor which for a '90 model is going to be relatively inexpensive.

Answered by caradiodoc (expert)
17,256 answers provided

Could be the blower motor bearing or the fan is rubbing against the housing -out of alignment

Answered by rasmataz
68 questions asked

Thanks for your advice! The noise really doesn't change much, if at all, when I switch fan speeds, but it sounds likely I need a new blower motor, since that seems to be the consensus. Thanks again!

Response from rosedale
1 question asked

several inexpensive GM heat fans from mid-90s fit and are cheap and easily available. Try the Chevy Chevelle or Capri

Answered by Enginer
0 questions asked

Several mid '90's GM heater motors are exact fits, try Chevy Chevelle or Capri. Much cheaper than Volvo sourcing

Answered by Enginer
0 questions asked