2004 Volvo XC90 Climate Control Blower

This is going to be tough to diagnose online? You need to be able to see what the climate control module sees as far as fan speed. So you will need a scanner that can actually look at the climate control module parameters? The fan itself could be bad, the fan module itself could be bad or the climate control module itself is bad? Also if the blower motor or the fan module has gone bad, the repair is not easy and it is not cheap. To replace the blower motor or the fan module you need to evacuate the A/C system, drain out the coolant, pull the dash out, and remove the climate box. I do not know what the heck the Volvo engineers were thinking when they designed this but to remove the fan, one of the screws is way behinde near the firewall that the climate box needs to be pulled out. So what I recommend is that you take it to a shop to have it properly diagnose and repaired.