Blower motor not working 98 s70 glt

[stephansvolvo]

Few months ago had and intermittent issue with the blower motor fan surging and going back to normal. Blinking lights on the ecc. Fan then stops working. I have heat and cold. Temp control seems to work. Fan doesn’t not engage. Things I have done
1) replaced the “resistor”, good used. Still no blower operation.
2) tested the blower in the car by unplugging it and putting power to it externally. Did not work. Replaced the blower with new. Tested prior to installing. Worked.
3) installed new blower. Did not work. Re-tested old blower, with external power. Worked.
4) pulled ECC from my V70 and installed. No change. Blinking lights.
Can hear the blend motors as I move through the area settings.
I have also pulled the fuse for it left it out for 15 minutes reinstalled and no change.

I have searched this forum, YouTube (Robert specifically), and other places on the internet.
I am at a loss.
If I have power to everything or at least externally, what would be causing the ecc to not engage the blower motor?
Will the blend doors keep the motor from switching on?
Will the cabin air temp sensor keep the blower motor from engaging even if I full send the fan speed?

Thank you for any help and guidance!

Stephan

[scot850]

Yes. The blower sensor will not work if it has failed or plugged. I have had one fail completely and nothing worked.

I did a write up with pictures a few years back on how to access it. You have to remove the radio and the ECC unit and it is tucked then to the left behind the small grille at the end of the row of switches. Read my notes as it is a little tricky to get to release and do not lose the rubber gasket that mounts to the front of the sensor. They like to stick and fall down inside the LHS of the dash center section.

Neil.

[stephansvolvo]

Yes. The blower sensor will not work if it has failed or plugged. I have had one fail completely and nothing worked.

I did a write up with pictures a few years back on how to access it. You have to remove the radio and the ECC unit and it is tucked then to the left behind the small grille at the end of the row of switches. Read my notes as it is a little tricky to get to release and do not lose the rubber gasket that mounts to the front of the sensor. They like to stick and fall down inside the LHS of the dash center section.

Neil.

Neil.
Thank you. I will give this a look. It becomes frustrating and costly(as per the Volvo usual).

Stephan

[scot850]

Well unless you have a bunch of spares or junkyards near by! I think I have about 10-12 of the cabin sensors and multiple fans and a few resistor units in the stash. I think I bought the cabin sensor for my current 00 R new from Volvo and was shocked at the prices. Then I found that local junkyards had lots of P80's in those days so started the slow fall into parts collector/hoarder!

The saddest part is I clean all parts (including nuts and bolts) and then test electrical parts where I can and then add then to a spread sheet with I think around 1400 part numbers. Many are nuts and bolts and smaller parts, but some not so small!

Hopefully the sensor is just plugged. I clean them with rubbing alcohol and Q-tips and a small artists brush. Then I spin them up after a light drop of lube like 3-in-1, I not have a 12V power supply for doing that, but in the past I used a 9V battery and a couple of wires. I don't have anyway of testing the thermostat portion, but hard to believe they go faulty. The motors seize with airborne particles including fluff and hair.

Neil.

[scot850]

This post from a few years back has some info on removing the cabin temp sensor:

viewtopic.php?f=1&t=70611&hilit=Cabin+t ... ure+sensor

Hope it helps!

Neil.

[stephansvolvo]

Still chasing this. Put a “new” cabin sensor in. Now I’m rereading Neil’s post about cleaning it. I will try this with the old one.
And report back.

[stephansvolvo]

The cleaning didn’t work. I bought a “good” used one. Cleaned that one too. Connected the 9v and it worked. Pugged it in and the ECC, Still nothing. Not sure what else to do. Any other thoughts ?

[abscate]

Put your ECC control unit into defrost. Then go down and look for 12 VDC at the fan connections. You;l need to fault trave backwards from there