whining noise

[gazzy]

I don't know if anyone can help but I've got a whining noise in the car,a 91 Targa.It sounds like the heater fan but goes louder on right hand bends and goes completely when the heat is turned down.Anyone got any thoughts coz it's driving me mad as I can't pinpoint the problem,thanks in advance.

 

[Dave Wilkinson]

Gary,

I suspect you're going to have to give us a bit more information if we're going to help. Is the sound inside the cabin or does it sound like the engine compartment?? Or elsewhere??

As you probably know, there are no less than 5 electrical fans in the 964 (6 if you have a/c) so saying it could be a fan doesn't help a great deal!!

The cabin fans (2 of them) are well known fro squealing - but I wouldn't describe it as a whine.

When the heat is turned down the rear blower is turned off. Could that explain the lack of noise?? Bearing wear in the rear blower could explain it but you need to check if the noise only occurs when the rear blower is running.

Waiting for your replies.

Regards

Dave

 

[gazzy]

Hiya Dave,it sounds to me like the noise is in the cabin,I thought it was the front nearside fan,if I turn the fan speed up it goes momentarily then returns.The front fans would't react to turning the temperature down though would they? the noise definitely goes when I do that.I'm hoping for a hot summer so I don't need the heater on and then it's just a case of avoiding right hand bends.I'll check the rear fan and try and see what the bearings feel like,I assume to get the fan to kick in and out I need to turn the heater up then down?

 

[Dave Wilkinson]

It sounds(!!) like it might well be one of the dash fans. They do have this habit of squealing as if the bearing is dry and will often stop if you turn the speed up. Lubricating the bearing is not at all easy and often not at all effective and replacement is the only real cure.

Interestingly, the front fans ARE affected by temperature selection, if only through interaction with the rear blower. If you have a problem with the rear blower such that it doesn't start up when heat is selected (i.e. control off the blue dot), the CCU will stop the cabin fans within a few seconds.

You can start up the rear blower with ignition on and turn the temperature selector towards the red dot and it should start up at slow speed. Turn the temp up to max (red dot) and the blower should switch to high speed. Anything different and you have a problem.

Regards

Dave

 

[gazzy]

Thanks for that Dave,I'll have a look this weekend see what I can find,any thoughts on why it's louder on right handers?

 

[Dave Wilkinson]

ORIGINAL: gazzy
.....,any thoughts on why it's louder on right handers?

Only a guess, but the axis of the dash fans is parallel to the centre line of the car, so if the bearings are worn, any centrifugal force acting on the body (such as going round a bend) would work against the gyroscopic force of the rotating fan blade and would cause the spindle of the fan to move sideways in the (worn) bearing. I can imagine that this would cause some change in the sound - one way or the other.

I know that sounds a bit technical but, to be honest, it's just a shot in the dark!!!

Regards

Dave