So, recently I acquired a 1995 960 sedan. The death of my 2004 S60 was tragic, but unavoidable. (19 year old girl drive her 1 moth old 2015 Nissan north on a west bound road)

Anyway long story short, 960, blower issues, randomly turns on and off never staying at a constant speed. Sometimes it works fine (on cool days) but on warm days it wont work a bit. So I am guessing it is the blower resistor (any opinions would be greatly appreciated) this problem is constant on all fan speeds. When it works, it works great! so I don't think its the blower (tested that) I also replaced the ECC to no avail.

So in order to get by until the stealership gets the resistor in (45 days) here is what I did.

As you can see in this photo there are 4 wires that go to the resistor. a black, blue/black (ground wires) and 2 signal wires pink and purple. The black wire is direct to ground, the blue/black wire is the one that goes to the blower motor, this is the how the resistor (which is actually a PNP transistor) regulates the speed (basically by switching the ground)

So I simply checked the climate control fuse and it was a 20A, it just so happens to fit perfectly in the connector, and BOOM cold A/C.
It turns on and off with the ignition, however it would be easy to run a pair of wires to a switch if you wanted.

 

I have a 1997 S90 that the blower motor just failed to turn on. Where is located the photos that you have posted for the temp fix with a 20 amp fuse. Also, how did you find the transistor at the Iroll parts website. There does not appear to be any rhyme or reason to the parts they list.

 

With climate control
CONTROL PANEL for 1997 Volvo S90|9134772

Without climate control
CONTROL PANEL for 1997 Volvo S90|9137027

As for location, if you follow the links they have a diagram that will show you where the resistor is located (labeled 7 in the diagram)