Belt Tensioner or Air Compressor

stravis

New Member
Dec 18, 2007
4
0
0
Henderson, GA
2003 GT 4.6 about 90,000 miles

I've got a strange problem that I want to get your opinion about. I've searched for the last hour and can find somewhat related issues, but not exactly what I've got.

The car runs fine with no sounds or issues at all. Then you turn the air on. Under the hood, the ac clutch pulley starts to spin immediately with no added noises (well, the pulley spins all the time, but when the air comes on the face of the pulley, or the compressor itself starts to spin). Wait about 15 seconds after the air comes on and the belt tensioner jumps about a half inch, then a horrible and loud screech/rattle/whine starts. Noise remains as long as the air is on while it is making noise, the belt tensioner doesn't move. Turn the air off and the noise continues again for about 15 seconds, then the tensioner jumps a little again and the noise goes away.

My first thought when I heard the noise was that it was the ac clutch pulley or the compressor. After watching from under the hood, it seems to me that the ac clutch pulley and compressor are fine, but that something may be wrong with the belt tensioner.

What's ya'lls opinion? What should be my first step? Replace the belt tensioner and belt since they are relatively cheap and rule that out. If its still there, try something with the ac?

Thanks in advance for any help.
 
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If it matters, one of the idler pulleys was slightly, very slightly loose. Cheap enough to replace, should I do so, or does slight movement not really matter? With the belt off, and turned by hand, it made a slight rattle noise.

Again, thanks in advance for any helpful replies. I haven't done much work to the mustang and am still a novice with it. It's my wife's car. I dearly love driving it, but just haven't done much work on it, so I'm relying on you experts. Thanks.
 
Check AC clutch bearings/friction surfaces

The front AC compressor shaft seals are bad about leaking (Ford TSB). This can cause oil contaminaton of the clutch friction surfaces.

I have also see problems with the load carrying bearings in the clutch give out. This causes the pulley to move under load.

So my vote is if it makes you feel better to replace the tensioner, by all means do so. Just don't be surprised if it doesn't fix the problem.
 
Of couse it will. The problem want be most evident except under load. The clutch needs to be engaged.

If the clutch bearings are almost totally shot, the outer pulley will have excessive play (in/out up/down).

I really suspect that if you remove the outside pressure plate you will find the inside filled with bearing material. This will also give you a chance to visually inspect the friction surface.

AC clutches are very difficult to inspect well unless partially taken apart.