2001 S40 Heater fan came on full speed.

Little history:

Occasonally the fan would go to full speed then back down to what I had it set too. This happens maybe a couple times a month other wise the system worked fine.

Today:

Temp set to 74, fan at setting 2, no AC, just heat.

All of a sudden the fan came on full speed and the air from the vents got cooler. The fan control does not work, but I can shut the fan off. If I turn the heat up higher I do get heat, but setting 74 is cool now.

Anyone see this before? How about ideas and component locations?

Thanks, Ed