2005 S40 2.4i I've tried searching on here and the internet in general, and had no luck. My issues are that the blower fan only works when it wants to, and the temp control **** doesn't actually change the temp of the air coming from the vents, regardless of whether the fan is blowing or not. When the fan DOES work, it works normally. It will adjust from off to high with no problem. The display on the dash shows any changes made to fan speed or temperature, but it doesn't guarantee that's what will come out of the vents. Even when the fan is working, the temperature of the air coming from the vents does not change no matter what. I have looked for the blower resistor but am unable to find it. All fuses are good, and I swapped relays just in case, no change. Anyone have any ideas?

 

Good chance the problem is the fan motor itself. If it comes on randomly (particularly if you give it a kick) then the brushes are worn out and the motor has to be replaced. The temperature problem is a separate problem - it could be a mode controller, or a bad heater valve.

 

That was my original diagnosis, but with the other weirdness going on, I'd like to check the resistor before spending money on a fan motor I don't need. After messing with it for a while, I'm less inclined to believe it's the motor since it works perfectly when it works at all.

 

Xemodex thinks a bad control unit can cause that -

https://xemodex.com/us/product/clima...0782566-10-20/

The fan is a 31332747, $331 from IPD. The blower resister looks like it's mounted on the fan itself, must not be easy to get to because Volvo wants ~4.5 hours flat rate to replace the fan - so hope it's not that .

And there is no heater valve, just a blend door

 

When my 2005 gave me AC trouble by randomly turning off the AC I replaced the CEM with a junkyard unit. The CEM is the middle waterfall display with all your climate and radio controls. No programming needed, plug and play.