2005 Bonneville SE AC ratteling noise from AC compressor

A sudden new noise heard from under the hood of my car!
I have determined The noise is definitely coming from the AC compressor. I can hear it when I lift the hood. The noise stops when the AC is turned off and starts when the AC switch is activated. I’m not certain if it is a bearing or one of the pistons inside?
Interesting is that there are moments that when the A/C is turned on, all is well, no noise and their is refrigerated air coming from the vents inside. But a mile or so down the road, the noise starts.
Also, once the noise starts, there is a tremendous load on the gas engine and the car has great difficulty getting to 35 mph.
The engine is a V6. the car is a SE model. There are Few bells and whistles.
There is 200,000+ miles on the car.
I don’t think it is a low freon issue, for is there not a built in safety that keeps the A/C clutch from engaging if freon ( or 134A in my case) is low? and when the unit does work, there is plenty of cold air.
I don’t think it is low oil in the compressor, as that would indicate a leak in the system , would it not?

Could I or am I , be looking at replacing the compressor?
Which will mean having to suck down the system, correct? and anything else I have not thought of that will be involved?
I am eager to read your replies.

If the compressor only makes noise when engaging the AC, it’s the compressor.

There are no pistons in the compressor as it’s a swash plate type compressor.

There’s more than just replacing the compressor and evacuating the system. The entire system has to be flushed out to remove any debris that the failing compressor deposited into the system. The orifice tube and the receiver/drier also need to be replaced.

Failing to follow these steps can result in a brand new compressor being destroyed in a matter seconds.


It often happens that with a little refrigerant loss over the years some compressor oil is also lost with it (normal) and a compressor can put out cold air while low on oil.

You can try injecting several ounces of refrigerant oil into the system and see if that solves the problem or at least helps it along a bit. It’s cheap and easy to do.

AC compressors sometimes have temperature controlled clutches, so they can be free-wheeling for a while even when the AC is switched on. That might explain why the abnormal engine load and noise isn’t present sometimes, even with the AC on.

“There are no pistons in the compressor as it’s a swash plate type compressor.”

They are unique axial pistons:



That’s called a swash plate compressor.


The swashplate drives the axial pistons. I remember the old parallel twin and v-twin compressors. The swashplate design is much smoother. My Hondas have had scroll compressors.

My heart felt Thanks to each of you. I have learned a great deal from you. The hyperlinks on the pumps, was tremendous help. i didn’t know those existed! Now to decide what to do and how much to spend. BUT first, let me ask each of you, :
what do you think of my adding a little bit of oil to the system to see if that corrects the noise?, and maybe I can buy oil with a dye so i can perhaps find the notorious leak that perhaps caused this problem?
PS: I wish I could get word to the moderator or web site creator, two things that would make it more enjoyable here for m at least: to make it so we can receive email notices when a reply is posted to topics we create, and that our profiles would link us to our topics, and or ones we are following. … any one know how to and wouldn’t mind forwarding my request?. I would appreciate it.

@flywelder‌, I’m happy that you found people’s answers helpful here. We’re very lucky to have so many generous and experienced folks willing to share their expertise.

I can tell you that you are able to get e-mail notifications when your topic gets responses, and your can see all your comments and discussions. Look up top, above the headline of your post. You will see Recent Discussions, Topic Index, and some other links in a shaded blue rectangle. One of those links should say “flywelder.” That’s the link to your profile. Click on it. Over to the left side of your screen, you’ll see a link to “Notifications.” If you click that, you can choose what you want to be informed of. On that same profile screen, the links under Notifications show your comments and discussions. It’s pretty handy, but not as obvious as one might like. Let me know if you have other questions.

In my experience? Once the compressor starts making noise, the system is rebuilt.


Given that the compressor does not make noise all of the time and based on the engine bogging after a few minutes of operation, maybe the high side pressure is going too high due to an iffy condenser fan which may not be operating all of the time for whatever reason.

It might not hurt to verify fan operation and if at all possible have the system pressures checked.