I have a 2001 Volvo V70 that the heat defrost fan climate control is not functioning, ideas? Is there a relay?

Has anyone hooked up a scanner to the climate control computer? it could be a relay, or controller,or a blower motor or a resistor. It also could be a loose wire or a fuse. I personally have replace more heater fan and resistors. Also make sure pollen filter is changed every 15,000 miles . One with a lot of debris will shorten the fan and resistors life