From reading around, it seems like this is the culprit#30864189, I ordered some transistors, I have 5 of them, and they are 2N3055. I pulled out my regulator and it has a MJ802 and it is a little hard to cross reference them but it seems like the MJ802 is more heavy duty. Although the 2N3055 is rated for twice the voltage?

I ended up putting back in my regulator after cleaning it up really good, hopefully that will do it for me but if it still has varying speeds at times, I guess I will replace the transistor.

Can anyone wheigh in on whether the 2N3055 will be an issue and if I order an MJ802, are they all the same, even if they have different #'s below the part #mj802.

Thanks this has been an ongoing issue but is not all that bad other than the sometimes revving/different speeds like it is possessed.

 

Cleaning it up did not do the trick so I may just pop in the 2N3055, would rather the MJ802 but that would take a while and since I have 5 of these, they will probably outlast my time with this car.

 

I have the same issue, and its NOT the transistors. The problem is corrosion inside of the potentiometers that are behind the climate control *****. I have taken my climate control box apart and sprayed contact cleaner/lube on all of the POTS, worked them back and forth per instructions... worked perfect for a year. The problem is now back but I'm too lazy to go through it all again.


Used CCM's are $$$ and likely to have the same issue considering that age, even NOS parts if you could find them might be pretty old.


there is a post on here, someone successfully replaced his POTS. Pretty simple soldering job but there are alignment issues to consider.


If my car was newer and I planned on keeping it for too much longer I might have tried this. I'm just waiting for this PITA Volvo to die already! lol

 

@Livens, thanks for the reply.

My first vent on CCM had a closed damper, this happened when I put it back in on one side that was not in proper placement. I popped open the vent and opened up the damper and put vent back in place. I do not know if something else got bumped while doing this but my air was running at a consistent speed.

This problem existed before the damper was in the closed position, that just happened recently. I will take a look at the potentiometers, glad I did not remove and replace the transistor.

 

100% my problem was with the transistor on the fan motor regulator. I replaced the MJ802 with an 2N3955 and it is working better than it ever has since owning the vehicle. I wish I would have known in advance that I should have ordered the MJ802 which is more heavy duty but if this holds up, I guess all is well.

It is certainly easy to replace and I have four more of the 2N3055 so I may very well just pop in another especially if it holds up for a year.

 

I have successfully replaced my POTS if anyone needs some help. The hardest part was finding the POTS themselves, to be honest. I think I ended up getting a pair from a forum user in Germany who bought some extras when he did his.


The soldering is pretty basic. In fact, I learned how to solder just to do this job and I pulled it off without any major problems.


The only curve ball is that the factor-installed POTS are calibrated once installed in the CCM's so that each turn of the speed/temp dial results in an even increase in fan speed/temp. When you put a new POT in, you may find that the interim speeds (between 1 and 5 on the ****) don't behave exactly right. In addition, you may even find that at the "0" setting, the fan still runs. The way to correct this is to pull out the plastic spindle behind each control **** (temp and speed) (easy to do) and hold a candle to it to bend it ever so slightly one way or the other. You do this until you get a true "0" on the fan speed **** and until you get the fan running at maximum if you put the temp to lowest and highest. It's a 10min adjustment at most. I did mine two years ago and have had zero problems since.

 

Here is a link to the resistor if anyone goes that route:
1pcs Motorola MJ802 Transistor to 3 TO3 NPN 30A 100V 200W | eBay