A/C Compressor or clutch making rattling noise

[Coley]

This was discussed here first:

http://www.ifsja.org/ubb/Forum2/HTML/000894.html

Is there an easy way to distinguish which one is making the noise. I think it's finally started to affect my cooling. When I feel the top line fitting on my compressor, it ain't as cold as it once was.

TIA

ps..in reference to the above linked post, at www.car-part.com, you can get York compressors for as low as $35. Most of the vendors have really decent warranties, too.
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Daddy's Ice Cream Truck (3 yr old daugter named it)
360 727 NP229
Totally stock
"You're obsessed with that thing!"

[This message has been edited by Coley (edited May 17, 2001).]

[This message has been edited by Coley (edited May 17, 2001).]

[JeepFreak]

Mine makes the same noise too. In fact both of my FSJ's make thats same noise. Blows really cold air too. I would think if it was internal that it would chew itself up but I have used mine for weeks now with no problems. I did spray a little lube on the clutch and the noise went away but returned after a road trip.

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JeepFreak

[Coley]

Jeepfreak,
What kinda lube, and where exactly do I wanna spray it?

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Daddy's Ice Cream Truck (3 yr old daugter named it)
360 727 NP229
Totally stock
"You're obsessed with that thing!"

[This message has been edited by Coley (edited May 17, 2001).]

[JeepFreak]

I sprayed mine with the truck running in the small little groove between the pully and the clutch. This did nothing so I shut it down and soaked it then and that made a huge difference. But it did come back. I used regular penatrating oil but Im sure there is something better out there. I had thought that maybe the front bearing was going out on the compressor but being an aluminum case you would think that the bearing would seize and spin in the aluminum but that hasen't been the case for me. I really do not have to much experience with AC stuff so Im really not sure what it is on the clutch that could be making the noise.

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JeepFreak

[David Simon]

When I started using my A/C again this year it started started rattling. I found some of the bracket bolts had loosened allowing the whole setup to vibrate. Hopefully it's that simple.
David


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98 Cherokee (wife's)
97 TJ with all the goodies
88 GW
NP229/TF727/D44s
TFI Upgrade
Free-flow cat, Flowmaster 70, 2 1/2" exhaust

[Mud Thrasher]

Coley, use a good lubricating oil with teflon or the such in it. Also, the not as cold could be a sure sign of low freon. I'll try and give you a call tonight about it.

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'78 Chief 360/quadra-trac
D-44 f&r/3.55 r&p/31x10.5x15 G/Year Mt's
dual exhaust
Mallory Unilite Dist.
Edelbrock 4bbl 1405 carb
lined gas tank
free rust/new body soon

[millerlo]

You have to remember that it is a clutch and by lubricating the surfaces that are to "grab" you can inhibit its ability to work properly. The bearing is a sealed type, and therefor cannot be lubicated. A proper sized puller or sometimes prybar, should bring the unit from its mount. Then, will be a perfect time to "spin" the bearing.

I use a contact cleaner (electrical) to clean the surfaces of the clutch and spring tabs (sometimes debis will become lodged under the inhibiting proper clutch contact). The clutch should not slip if properly taken care of. The high pressure side will try to stall the compressor when the thermostat engages the clutch, which torques the shaft, bearings, and clutch. This is one noise. The bearings, another. Reed valves, another. And so on. Internal "play" nets another noise more like a rattle as the shaft turns. A sharp ear is sometimes required in order to find your troubles.

Internal bearings can make a grinding sound, now, put them altogether.

Mike

Oops, I almost forgot belt flap!

[Coley]

I watched the compressor pretty closely yesterday:

1. The dual pulleys work smoothly when clutch is not engaged, and the belts don't flap until compressor clutch engages. I've already tightened the belt, I think it's just encountering resistance.

2. Checked the sight glass, and no bubbles or foam.

3. If I goose the engine, right after the RPMs drop back down, the rattle gets louder for a half-second, then returns to normal.

One question, and I don't know if this means anything. With the belts on, should you be able to turn the clutch on the front of the pulley if it's not engaged? Mine turns 3/4 rotation easily, then hits heavy reistance.

I'm gonna pull the belts and try to turn the pulleys with the clutch not engaged.

Found a decent tech article on the subject, even includes our Yorks: http://www.chekchart.com/PDFs/cc_hvac_sh_8.pdf

Thanks for the tips. Mudthrasher, give me a holler this weekend.

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Daddy's Ice Cream Truck (3 yr old daugter named it)
360 727 NP229
Totally stock
"You're obsessed with that thing!"

[millerlo]

When checking the output of the compressor, whether you have hoses and gauges attached or you are feeling the suction line for cold or the high pressure line for heat, the engine should be at about 1,900-2,100 RPMs.

Make sure you do not tighten the belts too much as this will stress the bearings and the shaft.

Make sure you turn the compressor the right way, you should have resistance due to it pumping up but it should not "lock".

Pull the belts and try to turn the shaft, I have put a wrench on the nut to make it turn and some of them have a hex hole in the shaft. See if you hear a grinding. The clutch bearing should be able to be spun a little.

Feel the suction line for cold (does it sweat?) Turn the ign. key on without starting it...turn the A/C on...does the clutch engauge smoothly and evenly?

Have someone bring up the RPMs while you hold a piece of metal on the top of the compressor, can you feel a rattle when it it backing down?

Sometimes a system can be overcharged and make sounds as you describe. A bug ridden radiator can make the charging of the sysem off. When charging the system some people just add freon until the sightglass clears, but, if one has a clogged expansion valve screen, or the evaporator has debris, the charging of the system will be off.

Take the temperature of the output (center). 43 degrees is good depending on which freon is in the system. Mine is lower. It also depends on the amont of air passing over the evap.

Most of these are things that can be checked without gauges, if you have a set of gauges, see if the high side needle fluctuates much, this indicates compressor valve problem, you can also get a noise from them as the unit backs down.

Does the unit whine?

When the compressor is turned off and the engine is also turns off, stick you head under the dash on the passengers side and listen for the expansion valve to equalize the pressures.

When you start the engine and turn on the A/C, how long does it take the sight glass to clear? Should only take a few minutes at most given the RPMs I mentioned above.

A/C troubleshooting can be tricky and frustrating at times. They work a certain way and should be kept within thier operating guidelines, deveations can shorted thier life. They can also wear out your wallet.

Mike

[Coley]

Much obliged for all the tips. I will get to diagnosin'!



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Daddy's Ice Cream Truck (3 yr old daugter named it)
360 727 NP229
Totally stock
"You're obsessed with that thing!"

[Coley]

The belts were too tight. Quiet as a mouse, now.

Thanks to everyone for the advice!

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Daddy's Ice Cream Truck (3 yr old daugter named it)
360 727 NP229
Totally stock
"You're obsessed with that thing!"