2005 V70 Climate Control/Fan with a mind of its own

volvooh · Post by **volvooh** » Tue Oct 09, 2018 6:24 am

The climate control on my 2005 V70 appears to have a mind of its own. At first I thought I had a classic resister issue with my fan. But when automatic climate control is engaged, the fan increases and decreases smoothly based on where the temp is set to. However, once the auto is engaged, it will not come back to manual right away- literally for days. When it does come back to manual, the manual fan control offers little to no ability to adjust the fan speed. It gets stuck in one place, either high, low or in the middle.

I still wonder if its a resistor issue, but if that is the case does the auto feature use a different method to control the fan speed? I also assume if its the climate control unit itself its not as easy as switching it out with another unit as you could with previous Volvo models?

Post by **abscate** » Tue Oct 09, 2018 8:35 am

Definitely vacuum out the cabin temp sensor on the control panel first - that can really mess things up with the ECC.

volvooh · Post by **volvooh** » Tue Oct 09, 2018 8:44 am

Thanks, Abscate. Would the fact that the fan speed can be controlled by the climate control rule out the resistor?

I am thinking it could be the ECU as well. What do you think? (hah)

Post by **abscate** » Tue Oct 09, 2018 8:47 am

volvooh wrote: ↑Tue Oct 09, 2018 8:44 am Thanks, Abscate. Would the fact that the fan speed can be controlled by the climate control rule out the resistor?

I am thinking it could be the ECU as well. What do you think? (hah)

Only if someone messed with it...

Yeah, if it works in AUTO (AUT) mode, then transistor speed control is probably ok. Maybe a bad pot on the Fan switch? Probably not replaceable though - hard soldered into controller.

All data says the V70 and XC70 use the same CCM software and it is not married to the car, so a PnP might be the route

volvooh · Post by **volvooh** » Wed Oct 10, 2018 7:38 am

Thanks- so just to verify your finding- I can buy a used climate control on ebay and replace the one I have in there now?

Post by **jimmy57** » Wed Oct 10, 2018 10:14 am

Make sure part number on both matches. If the switches plugged in are different or the panel around switches has a different count, you can move yours to the replacement. The location of the switches is also up to you if you want them in different spots. The switches send out a signal assigned to that function onto a comm bus so it does that job regardless or where it is placed in CCM switch strip.

Post by **abscate** » Wed Oct 10, 2018 12:38 pm

Isn't this how the Borg works??