96 SL 2 has a boring noise

The mechanic told my friend her 96 SL2's noise came from the A/C
compressor. The repair fee is even more expensive than the car. But till
now, everything works fine. Even A/C also works very well. Does she need
to get the problem fixed? What's the exact reason of so much noise? Thanks
a million in advance.

 

More description of the noise is needed. Many things could be making noise.
Alternator noise is common right before the alternator dies.

Ken

 

A/C compressor can get pretty noisy before they fail and it is not
uncommon at all. If you are mechanically inclinded, you might consider
changing the compressor yourself as they can be had rebuilt for less
than 200 bucks and then pay someone to recharge system. You do not
wnat to go to a dealer to get this fixed price wise.

 

Now I'm almost sure the noise comes from the A/C compressor. How long could
my friend still use her A/C? Would it last this summer? Is it helpful to
charge oil into the compressor? Thanks a million.

 

Depending on how bad the noise is, not likely and adding more oil will
raise head pressure and speed its desime. I have seen them seize up
and snap the drive belt when they get bad enough (it happened to a
freind a few years ago)

 

The first thing you really need to do is be 100% sure where the noise is
coming from. Replacing parts in a search of a diagnosis is an expensive
proposition.

Ken

 

AC compressor wear and noise is pretty common with age and easy to
acsertain too. No sense in looking for other gremlins that do not
exist and planting false hopes.

 

So what could I do now? It has been checked by another friend who is also
pretty sure the noise coming from the A/C compressor.

 

Replace it or wait tell it lets go and hope it does lock up first. If
it is a bearing the noise will be constant more or less but if it is
in the compressor internals, it will get loader as it get warmer
outside and pressure in compressor rises. Both are terminal but the
bearing is more li9kely to seize up suddenly one day.

 

Whenever I hear a boring noise in my car, it's usually the mother-in-law.

 

There is a lot of sense in being sure where the problem is, as it appears
the OP has done.

 

Well, I checked the car again. Although three friends told me the noise
coming from A/C compressor, I still couldn't be pretty sure. Since even
A/C is turned off, the noise is still there. Now I'm really wondering it's
from the alternator. I'll check it this afternoon.

 

Nobody has asked if the noise is occurring only when the AC is on or off.

If the noise is occurring only when the AC is on then the problem is in the
compressor and is easily solved by either immobilizing the system by
disconnecting the electric clutch wiring connector or by just not turning it
on. You can also use it until it fails and then disconnect it but this may
increase the cost of a future repair and may allow the escape of
refrigerant.

If the noise is only occurring when the AC is off then the problem is
probably in the electric clutch or the clutch bearing. I do not know if
there is sufficient clearance to change the clutch and bearing unit without
draining and opening the AC system but AFAIK it will require the use of a
specialized puller.

Get several quotes for the repair as there are lots of crooks in this end of
the business and you will find that the prices quoted vary tremendously.
Many shops will also quote a low price then after they get it apart will say
that much more work must be done. Make sure you have a WRITTEN agreement
for the cost of the complete job and which DOES NOT AUTHORIZE any additional
repairs.

Depending on your location and climate it may be better to just open the
window and remove the air system compressor and use the non AC belt drive
system. I have no idea whether this will require changing any belt drive
parts other than the belt.

I live in a climate that does not require AC and avoid purchasing AC
equipped vehicles whenever possible, it is an expensive luxury to purchase,
operate and maintain..

 

Thanks a lot. All the advices are very helpful. Would it be a big work to
uninstall the alternator if the alternator were wrong as NapalmHeart said?
The noise is on when the car is started no matter whether turning on/off
the A/C, which makes me doubt it's not the A/C compressor's problem.

 

Your problem could also be the belt tensioner, idler, power steering pump or
water pump or timing chain.

Take a piece of (clean) 5/8" or 3/4" ID hose about 2 feet long. With the
engine running, place one end of the hose in your ear and (carefully) point
the open end close to each moving component. Caution, do not wear loose
clothing or rings or long hair and do not allow the hose or anything else to
get caught in the pinch points. The hose will isolate the sounds that you
hear and should allow you to hear where the noise is coming from. A piece
of solid wood or steel dowelling can also be used if the bearing you wish to
check is accessible but the hose is easier and usually safer.

You may need to remove the right wheel and inner fender for access, make
sure you use solid blocking and do not work on the car while it is on the
jack.

Work carefully and safely. YMMV

 

You guys have him chasing gremlins. AC compressors fail a lot in older
cars and can get quite noisy and it is very easy to verify too.

 

Leeinwind, start with a cold engine. Remove the accessory belt. Hand
turn, spin in some instances, each component, ac pulley, water pump,
belt tensioner, alt, P/S... Also rock/move them back and forth to see if
they're sloppy. See if anything is abnormal, also check p/s fluid while
you're there. Now start the engine with the accessory belt still off. DO
NOT run it for no more than a minute. If you still hear that sound then
it is NONE of the aforementioned items! Wow that was easy!

Report back with your findings. Replacing parts without verification is
a waste of money and time. There is no reason to replace the a/c
compressor if you say that the noise is still there when it is off! The
compressor isnt doing anything when it is turned off. If it is coming
from the compressor it would likely be from the pulley's bearings and
that can be removed and replaced without recovering and recharging a
functioning a/c system. Doing so could create larger problems.

 

There's the word - verify. Make sure what it is before you start replacing
parts.

My son is driving the '96 SL2 I drove. 190,000 miles and the AC compressor
is working fine. All the other belt driven accessories have been replaced
at least once.

Ken