96 Volvo 850 - Blower motor intermittent?

Brahms · Post by **Brahms** » 19 Oct 2015, 10:15

So in the morning when I start the car the blower and the heat come right on. Later in the day the blower will not work. Also, I noticed if I plug in my OBD reader the blower motor turns off for a second, then it slowly starts again. Any idea what this is?

Post by **scot850** » 19 Oct 2015, 11:42

When was the blower motor last replaced? If this is the original it is nearly 20 years old and well past it. Also, have you ever cleaned the temperature sensor in behind the grab handles in the roof above the front doors? These fill up with crap over time and can't sense properly.

If you have the original fan, you could try removing it and lubing the shaft bearings with a little oil and see if it makes a difference. However, if it has worn out brushes in the motor it may make no difference.

Do you have ECC controls in your car (Electronic Climate Control)?

If you have ECC, if you move the control from AUTO to manual fan adjust, does it make any difference?

Neil.

Brahms · Post by **Brahms** » 19 Oct 2015, 12:07

Neil,

As far as I know this is the original fan, I have had it about 5 years now. Yes this has ECC, but shifting the control from Auto to Manual does not make any difference. I will have to try cleaning the temp sensors and see what happens and go from there. Thanks

Post by **scot850** » 19 Oct 2015, 12:20

The sensors are not too hard to get to, but just because you have cleaned them, doesn't mean they are still good.

On the later S/V 70's I always pull spares when at PnP and keep them around. They only have one in those and it is in the dash.

If I recall, to access them, you have to pull the trim (careful old plastic) that runs along between the door seal and the roof lining and down the side of the windshield on the inside.

Remove the screws from the grab handle and you can access the sensor. You may have to carefully pry the headliner board out a little to remove the sensor.

I usually use cotton buds and a small artist brush to clean the crap out with rubbing alcohol. After cleaning a spray a little silicon oil on the fan assembly. Finally blow it clean with an air line.

Again, PnP are a good source of OE motors, but often they may not be any better than what you have. Again I have several I pull. I have got the removal process down to about 10 minutes.

The last area of fault can be the resistor packs fail. This is what gives you the speed variation.

Neil.

Brahms · Post by **Brahms** » 19 Oct 2015, 14:09

Alright Neil, thanks for the instructions. I am going to clean out the sensors as you have and see what happens before I spend more money. I dumped some serious cash into her this year. I just want some heat for the winter now.

Post by **jreed** » 20 Oct 2015, 05:05

Does the ECC have blinking orange lights when you first start up the car? If so it can sometimes be of use to read the codes that the ECC has stored to help narrow down the area of the malfunction.

A starting point for troubleshooting, including making a code reader (if you don't already have one):
https://www.matthewsvolvosite.com/forums ... =1&t=50443

Brahms · Post by **Brahms** » 20 Oct 2015, 08:28

jreed

Yes, there are some blinking orange lights. I have a code reader, but not an expert at it beyond the errors. I will read that thread though. Thanks

Post by **cn90** » 20 Oct 2015, 08:50

You have a 2004 model, maybe the Final Stage Resistor (this controls the blower speed) goes crazy.
Info in forum.

Nice username, I love Johannes Brahms, my favorite composer!

Post by **jreed** » 21 Oct 2015, 05:08

Sounds good. Once you get the codes feel free to post them here and we can help out. Often there will be lots of codes stored and no easy way to tell which codes are recent and which are old, so sometimes it's a good idea to erase the codes and see which ones return and then hunt for the root cause of those first.

Brahms · Post by **Brahms** » 21 Oct 2015, 09:57

cn90 thanks for the compliment, yes I love Brahms too, as you can imagine.