heater blower is revving up and down when running
 

I just bought a 2002 Volvo S40. This is my first Volvo and I'm not very familiar with them. I've had the car for 1 week. I've been using the heater a bit at night, and I noticed the blower is acting very strangely.

I have it on manual, with front air vent exhaust, and no matter what speed or temperature air I set, the blower revs up and down constantly. If I set it on 1 for example, it runs low, then revs up and the blower increases like I just turned it up to 3 or more, then it revs down again, then back up, etc. - if I turn it up higher like 3 or 4 or 5, the same thing happens - the fan speed seems to be all over the place. Even with me in park, with my foot off the accelerator, the fan speed is still up and down constantly, every few seconds. It definitely doesn't seem right, but I"m unfamiliar with Volvos. Is this normal? Should this be happening?

I would think that if I set it to a specific speed, like 1, then I would want it on 1, not up and down in speed. The circulate is turned off, but I tried it with circulate on also and there was no difference. It's been doing this since I got the car last week. Any idea why this i happening? What should I do about this?

I can not tell you what is wrong but I can tell you they have had a good bit of problems with the climate control going bad and it is very pricey to get it fixed. You would have to buy a new module and then have volvo get the computer on the car to recognize it. I have similar problems and last I checked it would have broke $1000.

You've got to be kidding. I just bought the car 1 week ago and I'm already looking at a $1,000 repair? There's just no way! I don't suppose something like this is grounds for demanding a refund? I bought this at an independent small dealer, and he told me there was nothing wrong with the car. I also had it checked out before-hand at Pep-Boys and they said everything seemed fine. I highly doubt they would have bothered checking the heater/climate control though. Come to think of it, I wonder what they did check.

This is thoroughly depressing. With winter coming, I can't deal with this issue. My girlfriend and I have no money to immediately pour into this car for a repair like this. If we had known this car was starting out with an issue like this, we would have skipped it. As it stands the climate control is thoroughly annoying and I wonder if this is just the first sign of it failing. Maybe that's why the previous owner (owners) got rid of it - it had 2 owners - the last one no more than a year.

This thread:

https://volvoforums.com/forum/volvo-...r-fault-14920/

seems to suggest that it could be the Fan Speed Controller Module.If that's the case then it sounds a lot cheaper than $1,000. $100 I can deal with. Does anybody have any input?

If you are into it you can take it out and look at the circuit board. Sometimes you can get lucky and find a cold solder joint. They should all look shiny with no flux (looks like grease). If you see one that is dull or has flux on it, this can be a sign of a cold solder joint (meaning the solder joint did not get enough heat to make a good connection). If you do just take a soldering iron to it for like 1 to 2 seconds. I tried this with mine but did not find any cold solder joints. I have done this with electronics before and have been successful, but I feel lucky when it does work.

What does the climate control do in auto?

When mine acts up I just turn it off and on a couple of times and it goes away. I have learned to live with it. The other problem it has is it does not always switch from hot to cold or cold to hot. So I just leave it in one spot and it will eventually go.

If I just got it I would at least call the guy and see if he would pay to have a Volvo dealer check it out and go from there so you are both on the same page with what the problem is. My buddy was a parts guy for Volvo so he is the one who informed me of this problem and how to fix it.

In response to the other thread, could be, my problem does have more to it.

I'm not really comfortable poking into the car myself. I'm not very good with cars honestly, and I know nothing about Volvos. I think I'll take your advice and see if the dealer will agree to pay for a Volvo repair center to check it out. My concern is being an independent he'll probably try to get away with taking it to some place that's not certified to work on Volvos. For some things that might be okay, but for something like this, it sounds like something that should be handled by a Volvo tech, since they should know all about this issue it seems.

Thanks for the info! Hopefully I can avoid having an expensive repair bill right out of the gate.

I see there's a difference if the car has climate control or not. I have a 2002 S40 and according to the manual it has "electronic climate control". Some mention a "power transistor" and others mention a "Blower Motor Resistor" or "Fan Speed Controller Module". Not sure which I would need. If I can at least get the guy to cover the diagnostic and half the repair cost it might not be so bad. I'll also replace the cabin air filter as well since that seems to contribute to it overheating maybe?

Thanks for all the comments! I'm glad I found this forum, I think it will prove helpful for me.

Good luck, if he is a good guy he should at least work with you.

The power transistor and blower motor resistor are the same thing. Basically your fan motor's power runs through a transistor mounted to a heat sink. The heat sink is mounted inside the air ducts under the dash. The airflow keeps the unit cool. Over time the transistor portion wears out. The good news is you can replace the transistor with a $3 Radio Shack transistor. Or you can buy the $100 unit from Volvo and have them install it for another $100 plus. Prices made my decision.

This is the whole unit: transistor mounted to heat sink-
Attachment 17576

This is the transistor from Radio Shack, 2N3055 NPN

Attachment 17577

Thanks for that info, Hudini. This forum is already helping me out and I just registered last night! Very much appreciated.

Question - I am reading some comments that for cars equipped with ECC - electronic climate control (like mine), it doesn't have a blower motor resistor - instead it's controlled by the A/C Power Module. Does that make sense for this vehicle? If I type in a search for the blower motor resistor for the 2002 S40, I get tons of hits for that part. From what I can tell, the 2002 S40 came standard with the ECC electronic climate control. Is this correct? I checked available packages, and it doesn't seem like ECC was an option, and it isn't listed in the manual as optional.

So then does my car have a blower motor resistor or not?

Do you know anything about not transition from hot to cold or cold to hot. I already replaced the actuator with no luck.

Make sure you have plenty of coolant in the radiator and overflow tank. I once had a no heat situation due to a low coolant level.

I had the same problem with my heater, i've change the fan motor and works fine now. Put on a used one for $125.00

I had the same issue and when I removed the resistor on the heat sink I noticed a white grease underneath of the resistor. Is this dielectric grease or something different? Also, should I clean this off of the heat sink and apply dielectric grease or only on the two terminals coming off of the resistor?

Di-electric grease is an insulator. I would only use it where you need protection from water. I think you need the silver heat sink compound stuff you also find at Radio Shack. I soldered the posts to the old wires and covered them with tape. Not much room in there for shrink tubing.

Attachment 17177

Your information is still valid and useful after all these years. I just repaired an S40 blower motor control by replacing the transistor.

Thanks much for sharing.

Nick

Cool. Realize the Radio Shack part is not very tough. After a while the fan will start varying speed again. There are heavy duty units available from other sources online if you want a more permanent solution. For a couple bucks and a couple hours though, the Radio Shack version is not that bad.

I used a MOSPEC 2N5881 out of my parts stock, don't know if they are any better or worse than the Radio Shack version. In my work with auto radios sometimes it's necessary to build a 12-6 volt dropper and using this transistor allows the solid-state voltage regulator to provide above 1.5 amps.

Suspect that it's heat causing the failure, I used heat paste on assembly.

Thanks again and I've got another to replace if necessary.

Nick

Removal instructions?
 

Where is the unit mounted under the dash? Any instructions for removal?

Thanks and regards,
Stephen Tinius
2001 S40
Myrtle Beach SC