Up for sale is a good used volvo blower speed regulator. 3506972  . Will work on many early 7 series volvo cars. - typical to find on 740 Turbo and Bertone models. check your part number off your original as not ALL will interchange with these. The typical failure on these is causes the loss of one or more of the climate control fan speeds, or total loss of fan function. These can also cause blown fuses. List price at Volvo USA was previously nearly $300! get this one for less than you would pay in tax at the dealer! I only sell the OEM units, never aftermarket so they are the same quality as your original.  Often times when you have a resistor failure it is because the terminal has gotten too hot and it melts your wiring as well. - this can be caused by several things, however the most likely is a BAD blower motor. 

Unit is a good used unit, and I will offer a 30 day functionality guarantee ,Thanks for looking and good luck!