Blower for heat and A.C. won't blow! What to do?

Sounds like its most likely the blower motor has gone bad. In most cases its located under glove box on passenger side behind a plastic panel or kick plate. The panel may be shaped somewhat like blower.

snowflake light comes on when the outside temperature is 2C (36F) or less. the snowflake is another safety feature, warning of the possibility of freezing. You've really got to love Volvos. do you have the owners manual? when you turn the fan switch/blower motor on,does it blow air at ANY speeds selected from ANY vents including DEFROSTER? have you checked the FUSE for the blower motor?