Things work better when accelerator pressed

I recently had to replace my drive belt on a 97’ dodge grand caravan sport 3.3 engine. The belt shredded and this is how i knew i had to replace it. Since i replaced it i notice a whine type of noise that increases in pitch as the engine is accelerated. The other thing i 've noticed is that all electrically related operations work better as it is accerlerated. For example, the air blows harder, the wipers move faster, and the lights brighten. Now i honestly can’t say that it didn’t do this before i changed the belt. I wonder if a bearing is going out on a pulley. I have noticed the same behavior on my daughters 98 sable. Can anyone tell me if this is normal behavior or if i’m in for a world of hurt down the road. Also note that i did get all of the pieces of the old belt out from the pulleys and i did spin each of them to macke sure the were moving without any resistance. Thanks, Lar.

This sounds like an alternator issue. I’d have someone load test the battery & alternator. Many auto parts stores will do a basic test for free.

I agree with cigroller here. The bearings in the alternator are more than likely shot. Increasing engine rpm will increase voltage on a bad alternator in most cases.

I agree with the alternator theory, but I wonder if there may be a bad diode in the rectifier bridge in the alternator. I don’t know why a bad diode causes the whine, but I have had alternators make this noise just before they failed due to a bad diode.

I think either the belt is too tight or the new belt has caused a failing bearing to get noisy. Things working better when you push the accelerator could be a weak alternator, but I’d have the battery checked first. A battery with a weak/bad cell would do this too.

Well, it might be some of the above but it might be that the belt is loose. Maybe the tensioner is faulty, or wrong belt.

The tensioners on these vans have a tendency to freeze up where the roads are salted. Then when the belt wears or stretches the belt becomes loose. More rpm will create enough friction to heat up the belt and make it grab. As others have said, it could be a failing alternator. It won’t get cheaper to fix if you wait, and could damage something else. The most expensive auto repair plan is sticking your head in the sand.

I too think it’s a bad alternator diode.
The bad diode throws off the balance of the 3-phase stator windings.
The uneven torque of the spinning rotor makes the whine noise.

Thanks for all of the advice. Bad diode was the culprit. The warranty on the alternator would have expired in 27 more days. So i guess there can be a good time for something to break. Thanks again, Lar.