Blower motor or resistor (controller) bad? RESOLVED Topic is solved

kjhiggins · Post by **kjhiggins** » 11 Sep 2010, 16:17

I have a 2004 XC70 and the blower stopped working suddenly last week. I've seen many posts here about this problem but none that address how exactly to test whether it is the motor or the resistor/controller (it has ECC). I've removed the motor and controller pack following instructions here and when I connected the motor directly to the battery in my other car and it seemed to work just fine. When I reconnected the controller to the four prong plug under the dash and check the output to the fan at the two prong connector I get a steady 12 V regardless of whether the fan switch is on or not, and even if the key isn't even in the ignition. If I then plug the fan back into the controller it doesn't spin and I get 0 V at the fan terminals. I suspect it is the controller that is bad but I'd like to be certain before I go out and get a new one. Any suggestions as to how to definitively test it? Thanks.

ed7 · Post by **ed7** » 11 Sep 2010, 20:47

I gotta say it... did you check the fuse?
Three fuse boxes confuses things a bit, I know.
I think it's #26 on the left end of the dash.
I've found the fan will work on High only if the resistor's bad.
Also the ground point behind the passenger side kick panel could be bumming.
You've conclusively ruled out the fan. Onward...
ED7

kjhiggins · Post by **kjhiggins** » 11 Sep 2010, 22:34

Thank you for the response. Yes, I did check the fuse and it looked good but I replaced it with the spare anyway. The fan doesn't work on any setting in the car, either on 'auto' or manually adjusting the fan speed. Does anyone know how the fan output from the controller varies with fan speed setting? As I mentioned, with the fan disconnected I get a steady 12 V measured across the two prongs of connector on the controller, and it doesn't matter if the ignition is on or if the key isn't even in the ignition.

kjhiggins · Post by **kjhiggins** » 14 Sep 2010, 19:40

Turns out it was the power unit/resistor that was bad, as suspected. It's all back together and running fine.

goldmandan · Post by **goldmandan** » 30 Aug 2014, 20:54

Where is the power unit/resistor located on the 04-05? how does it look like? I would like to know so I can resolve my fan motor running on high all the time

Dan

Post by **DGM** » 31 Aug 2014, 05:11

goldmandan wrote:Where is the power unit/resistor located on the 04-05? how does it look like? I would like to know so I can resolve my fan motor running on high all the time

Dan

Read the following, it will answer your questions.

https://www.matthewsvolvosite.com/forums ... =9&t=21343

Thames · Post by **Thames** » 13 Jan 2015, 10:00

HI guys, having the same issue here on a 2005 XC70. Can we test the resistor pack ?

Moreover, about 10 days ago, I removed the blower to give it a good cleaning (blower was noisy). It worked flaslessly until today...

adrian22 · Post by **adrian22** » 12 Aug 2016, 08:03

XC70 2006 blower motor is not working when I started the car after one week in the garage.
1. checked fuse #3 on the LH dashboard- is good
2 checked fuse #10 Instrument panel, climate system, power driver's seat-is good
Question :do you know if there is Volvo xc70 Blower Motor Relay or other fuse responsible for blower motor?
I know the motor has included in the same unit a speed controller but if I understand correctly if the controller is bad the blower will make some move or noise/hum?

BryonTheCanadian · Post by **BryonTheCanadian** » 09 Jan 2019, 13:50

Is there a electronic controller module for the heater on this car ? beyond the resistor? My heater has stopped completely and heading to wreckers. want to make sure i gather all possible parts

Thx

Post by **abscate** » 09 Jan 2019, 14:16

The whole front face plate of the climate system is the controller - harvest that.

Make sure you harvest the CEM and the PEM near the fuel tank too - good 50-100 dollar part.