2005 XC70 ECC fan speed control working intermittently

Stoneworks · Post by **Stoneworks** » 30 Jun 2025, 20:24

Over the last few years the blower fan speed control knob has been having episodes of not working very well, and getting worse. I can rotate the knob and it won't do anything, or doesn't change the fan speed with each click if it does work some. The led still indicates the fan speed correctly. The last good Volvo tech that worked on the car said the speed control switch? was going bad and he could only replace the entire module, about $3k plus labor. He did say there was a thread here where someone replaced the switch and even had the part # for the switch from Mouser, Digikey, or such. I have been searching for any info for a few hours now without finding the right info, so now I am asking for help, please.

Today it was close to 100f when we got in the car to go to town, and no blower! I messed with it awhile and when I pressed on the knob then rotated it worked well enough to adjust the fan speed. It does seem that the hotter it is the more it acts up. My wife has been wanting me to deal with it and is now getting adamant.

Any information would be appreciated.

Thank you,

David

Post by **matthew1** » 30 Jun 2025, 21:10

Thanks for choosing MVS and welcome, Stoneworks. I would try cleaning the cabin temp sensor: search.php?keywords=cabin+temp+sensor&t ... mit=Search

If that doesn't work, look at these threads about the knob:

viewtopic.php?p=575629&hilit=blower+spe ... ob#p575629

viewtopic.php?p=411729&hilit=blower+spe ... ob#p411729

Stoneworks · Post by **Stoneworks** » 13 Jul 2025, 10:35

I vacuumed out the cabin temp sensor, with our 3 stage built in home unit, and the fan speed control is working near flawlessly now. I do this whenever I vacuum out the car so it wasn't that dirty to start. Here is a video I found quite interesting on working on this switch.

https://www.youtube.com/watch?v=E1PC3boBPLM