Okay, so I can't seem to find any topics on this, I know it's been discussed so if anyone has a link or doesn't mind re-hashing I'm much appreciative.

My fan speed position #4 is NOT working. #1-3 are fine, but when I switch it to 4, the fan shuts off. A/C and heat are working (blows cold) I ran down to the volvo graveyard and pulled a new switch out of another car and the put it in and still no luck. I don't think the resistor is the issue because the switch positions 1-3 are fine. Oh ya, checked the fuse and that's fine too. What else am I forgetting??

Wow, maybe this isn't as common as I thought. I've been looking around and I've seen some information on a possible relay. Does anyone know if the blower fan uses this and where it's located?

Thanks in advance!

Sorry I cant help you on this.

But the radiator fan relay is just above the radiator.
Not sure about the blower fan relay though.

Look for the fuse box under the hood at the base of the windshield. it should be on the drivers side. press the button and open the cover. if you read the cover, it will tell you which fuse to look for. the #4 fan speed setting has its own fuse. check the fuse. it is the easiest thing to do first. hope this helps. sorry, didn't read the whole thing, bone head alert. sorry everybody.

Greekmason,

Thanks. Its a lesson for me too.
:)

No problem! I do the same often...

Anyway, I've been asking around and I hear that there is also a blower fan relay underneath the glove box somewhere. Looks like I'll be tearing that apart this weekend. Fun.

Another mechanic at an independant volvo shop told me that the blower fan itself might be bad. I don't understand how lower speeds could work but not the high one if it were the fan. He had no explanation, just said that it happens. Regardless I won't be going back to that shop for advice any time soon and further more, I replaced the blower fan last year and I seriously doubt that's the problem.

Thanks for the advice! I'll keep posted on what happens... If it hasn't happened yet to anyone here, I'm sure it will eventually!

97 Volvo 850 Non ECC, non turbo.

I have a similar issue, except the first 3 settings don't work unless the car is moving. I checked both of the position fuses, both are good. Anybody have any other suggestions? The A/C relay will be changed next I guess. The odd thing is
when the vehicle is stopped there is no air flow out of the first 3 speed positions, the only air flows on the 4th position while motionless. It air flows on the first three while moving but the output appears to be less then before the issues occured.

More updated information, Both of the relays behind the glovebox on the blower itself are the same, they are green relays volvo part number 94994787. The relay on the left (1) can be removed and the blower still runs. I swapped left to right and still no air with the first 3 positions, the 4th position still works. So the relays are both functioning. The relay on the right (2) must be in or it doesnt work at all.

What else can I check, any other thoughts?

Thanks in advance...

Robert

Usually, this refers to problems with the SWITCH itself.

Thanks, I was planning on trying to change that out this afternoon. I'll post results once it's been replaced.

Robert

You also might want to replace the blower motor resistor. Usually when the fan is not working on positions 1-3, it's the resistor. It may feel like the fan is working just from the air coming through the system due to the motion of the car. It could also be a bad blower fan motor. I had these problems and I just replaced both the fan motor and resistor since they are in the same place below the glove box compartment.

I have the exact same problem. Did you figure out exactly what it was? Was it the fan resistor or blower motor?

Even If you want to try the easy ones first, it'd still be the trim-switch / resistor.

Cheers.