Fan stopped working

[goldxc70]

Just bad luck that as the weather turned cold, the fan on my 04 XC70 stopped working. Everything else on the CCM is fine, all bulbs light up and all LED's work as well. Just no fan on either manual or auto settings. Given the fact that it was only the fan, I went to the fuses and found no problems there. Next I pulled out the fan/resistor from behind the glove box and checked those. Both appear good. Also took a look at cabin temp sensor (thermistor) to see if it was gummed up but no problem there. And the thermistor itself appeared to be OK (that is, no broken connection). Swapped out the CCM with one from another XC70 but that made no difference either. Compared the resistance readings across the thermistors on both units (powered down) and got identical readings.

Any ideas?

[FirstVolvo]

Not sure how you checked out the blower motor but an easy check to see if the motor is working is to unplug the two pin connector that goes to the motor and apply 12V to these two terminals. Motor should run, if the motor does run with 12V applied then it could be the resistor module causing the problem. I think you'll have to pull out the blower motor resistor assembly to remove a cover for access to the two pin motor connector.

[goldxc70]

Not sure how you checked out the blower motor but an easy check to see if the motor is working is to unplug the two pin connector that goes to the motor and apply 12V to these two terminals. Motor should run, if the motor does run with 12V applied then it could be the resistor module causing the problem. I think you'll have to pull out the blower motor resistor assembly to remove a cover for access to the two pin motor connector.

Thanks.
I've checked out the original blower motor in the car and on the bench and it works with 12V applied. Ditto a second motor from a local scrapper. I have a new OEM resistor which I've tried with the original motor in the car but no luck with that. Tomorrow, I'm going to try that with the second motor.

I'm pretty sure - but not certain - at this point that I've got a CCM issue. Nothing particular happened to cause a problem: I didn't jump start another car or even disconnect the battery.

[FirstVolvo]

It might be a good idea to check for 12V at the 4 pin connector that plugs into the fan control module, which comes from fuse 26 to pin A2 (2002 wiring diagram), to verify 12V is getting to the fan control module. Also measure continuity to ground from pin A4 of the connector.

[goldxc70]

It might be a good idea to check for 12V at the 4 pin connector that plugs into the fan control module, which comes from fuse 26 to pin A2 (2002 wiring diagram), to verify 12V is getting to the fan control module. Also measure continuity to ground from pin A4 of the connector.

Followed this https://youtu.be/xX3qrdBEn-I but no success so far. Going to pull things apart again tomorrow to try and figure out what's what. Last time I checked, I verified power at all the obvious places from the fuse to the four pin connector to the motor.

A1 BLUE CCM
A2 RED 12V
A3 YELLOW CCM
A4 BLACK Ground (G10 at Right Kick Panel)

[Astro14]

You swapped CCM, so, I’m thinking it’s not CCM. Check the grounds.

[goldxc70]

Been too cold here for the last few days so haven't done anything more. Seat heaters are still working so OK to drive until the problem is resolved. Hopefully will be able to update this thread later today or tomorrow.

UPDATE: Last night, I pulled the connector to the fan module/resistor to see if I was getting any input from the CCM. The readings were meaningless but I could see a definite change when I adjusted the fan speed up and down. Then I plugged in the original resistor and checked the output from that - nothing: scrapyard resistor - ditto; new resistor - changing voltage with fan speed. Tried original fan with that - nothing; scrapyard fan worked. Put everything back together and reinstalled. Everything is working but the fan is really noisy at certain speed settings. Hopefully, it will improve but, if not, putting a new one in will be a simple job.

PS both fans worked with 12 volts but the original fan would not work in the car. Actual voltage at top fan speed is less than 12V. Voltage/fan speed is varied by raising voltage on "ground" side.

Thanks for the suggestions.

[vova]

I think you possibly have a worn fans. I believe they have 2 bearings which are prone to get "dry" and using brushes on the bottom. I recently had similar scenario which was found to be due to worn fan. I went with FCP Mahle/Behr fan and replaced resistor at the same time(usually they fail around the same time and worn fan was not contributing to good health of resistor as well). Works pretty decently now. There is a very mild noise at low speed, but not enough to justify $560 for an oem fan. You already put transistor, just put a fan and be done with it. Summer is near and those heated seats will not save you
ASTRO mentioned grounds which is a great suggestion. Check the wires for corrosion and clean if needed. Also while you are at it, make sure you open the hood and clean around the air intake drains(drains are subjected to clogging overtime and water might end up pouring into the cabin on top of your fan and new resistor and might cost you money. Just take couple clips off from right side next to windshield enough to get access to the cabin air intake area and clean good there and test drains) good luck