spike2450

Hi
Had my 1998 cherokee for about a week, thanks to this forum i've now found that i have a noisy ac compressor.
For the last two days when driving, and after about 10 minutes there was a bad dry grinding bearing noise which initially thought was a f****** engine.

However i've found that when switching the ac system on, the clutch engages as it should on the ac compressor and there is a loud grinding noise (hard to describe exactly).

Any help as to what i should look at first, and another point that i can't understand is that both times when driving i've had the ac system completely off and still had the same noise.

Does the compressor cut in at any time when the ac is off!!!

If i continue driving and put up with the noise for now will i cause any damage elsewhere.

Thanks again

Kyle

Are you sure its not sort of a screeching noise? Like a belt slipping?

spike2450

Hi
No pretty sure it's not the belt, had a good look again and it seems when the clutch engages the pulley actually twists / tilts in towards the engine under the belt tension. Does anyone think that it could be the front bearing, i.e. it will make a noise without the clutch being engaged.

Does the compressor ever run without the ac being on?

On another post a question was asked " does your volmeter drop when the clutch engages" but here wasn't a reply however my voltmeter drops!!! does that make a difference?

All posts are appreciated

regards

Kyle

Its normal to drop a bit because of the sudden increase in power needed but how much are you talking about?

BlueXJ

Can you rock the A/C clutch with the engine off? If you can move it over a couple of mm then you might have a front bearing going bad. You can not replace that w/o having to empty and replace the compressor pull a vacuum and refill your whole system. Some of the Sandens can have the cllutch packs replaced w/o replacing the compressor or so I'm told. Never seen it done or have any personal experience.

spike2450

Hi
No the only slight movement is on the pulley which i can push out away from the engine on one side (engine side) but that is only a few mm.

It only drops a few volts which i'm now happy with.

I've tightened the belt and tried spraying it with water and she was still making the same noise.

I don't now believe that the ac compressor has been coming on i believe it must be the pulley or bearings.


UPDATE

Took her out for a spin and when i put her into drive the noise immediately restarted, (AC off).

Does putting the jeep into drive create more torque onto the belt and thus causing the bearing on the ac pulley to squeal.

thanks for the help

BlueXJ

With the A/C in the off position the compressor does not spin. Unless the clutch is engaged the pulley should spin freely. The squealing may not be the A/C compressor.
After the squealing starts will it continue while you go look under the bonnet to try and pinpoint the origin of the noise. If not you may need somone else there to run the engine while you go listen under the bonnet for the noise.
Report back after a closer inspection of the origins of the squealing.

spike2450

Hi

Started her again, no problems running sweet.

Switched on the AC

Clutch engages with no noise

As soon as the clutch disengages i.e. spinning freely there is a loud grinding noise.

Clutch engages and the noise stops and so on -

Switch off the AC and after about 20 seconds the noise slowly dies.

Something is grinding when the ac is on and the clutch disengages!!!

What puzzles me is that i occasionaly get this noise when driving and the AC has been off.

I think i might need Columbo on this one


P.S I presume that the clutch on the AC should be engaging and disengaging every 15 seconds or so?

BlueXJ

It does sound like a bad clutch. If you have a Sanden then check with your local A/C shop to see if a new clutch assembly is available there for that unit.
Yes the A/C wil engage and disengage dependant upon pressure within the system. There are low and high pressure switches within the engagement cycle wireing.
This has been a little bit hard to follow so I hope your questions have been answered spike.

fdulax13

I have the exact same problem, sometime i even hear the squeeling sound when i first turn the car on....but not always....still trying to figure this one out

spike2450

Hi

From what i've learnt so far is that you have to first eliminate a slipping serpentine belt, lots of threads with tips on tightening the belt.

Try running initially with your AC turned off and see if it squeals.

I'm going to unplug my compressor tonight until i can get one cheap of ebay as i'm in the U.K. we rarely see the sun anyway!!!
From what i can gather unplugging will not cause any adverse effects and is a way of eliminating the ac compressor/clutch from any other noise investigation.

If anyone disagrees then please post.

Thanks again to all the help

Good luck

BlueXJ

Sounds like you have a good plan!

spike2450

Hi

Unplugged the AC

Took her for a spin and after about 5 mins of driving that same grinding noise started.

So I've loosened the serpentine belt and spun all the pulleys and low and behold the compressor pulley sounded awful when spun and there is plenty of side to side rocking movement.

Can i presume now that the bearing is shot, should the plastic pulley rotate smoothly i.e. on the bearing with no rocking movement???

Ideally i would like now to change the clutch and bearing is that possible without the special tools. Is it possible to get to the bearing etc. Or should i just go for a second hand complete unit of ebay and recharge the system.

Regards

BlueXJ

As I stated earlier I have heard that some of the sanden compressors have changable clutch packs. Don't know if you have one of those or not. Even if you do, I am unsure if they are available across the pond or not.
A good A/C shop is going to be your best bet because the coolant is detremental to the enviroment if just dumped. And a vacuum must be pulled before the system can be refilled.

fdulax13

As i stated, i have the same problem. Since the problem started, i have changed both the compressor and the pump and still have the EXACT same sound. I can't be sure that what i'm hearing is what your hearing, but by the way you describe it, it seems to be the same sound. I'm not sure if your compressor is the problem