I'm finding that on my non-turbo Volvo 850 Wagon, (5 cyl 2.4L, Automatic), there is a vibration from "engine" area when I put the inside Fan on setting 4. This is the fan that blows into the cabin, for ac, heat, etc.

This is regardless of whether the air conditioner is on or not. Or in Heat, or vent, etc.

The vibration is felt in the gas pedal, and I notice it as what feels like engine/trans vibration. It is less when the gear selection is in neutral.

But the real item is placing in 4 setting. There might be a little of the vibe in setting 3, but none of it is noticed in setting 1 or 2.

Any ideas?

I've only had the car a month, and have a few repairs done, by specialists: radiator & upper & lower hoses replaced, cam shaft oil seal replaced, boots on the cv, t'mission fluid change.

I don't notice the vibration change as much (?at all, hard to tell), at higher speeds. It is mostly at idle or low speed.

Thanks for ideas, or clarification that it's normal.

 

Check to see if the fan motor mounting screws are loose. The fan motor is under the passenger side glove box. Does the fan make any abnormal noises (screech, loud whine, etc...)? Only other rhing I could think of is when the fan is on high it is drawing enough current to put a load on the alternator, causing a slight engine idle vibration

 

The fan itself is very quiet. The only sound is that of air thru the vents.

I wondered about "load on engine". But turning off AC compressor (a big load), radio, lights, don't effect the vibration. And it is definitely in the gas pedal - transmitting from engine, and changes frequency/amplitude between park & neutral.

Thanks

 

PRetty much sure on that your blower motor is loading the electrical system when run on higher speeds. This could be just because of aging of motor or lack of lubrication. What happens is that when you put it on '4', It starts to draw more current than normal and to make up for its load on electrical, the alternator starts working hard thereby increasing viberations on your engine.