Is This Noise From Clutch or Inside Compressor?

[genistas]

Hello everyone,

I recently replaced the A/C compressor in my 2009 Mazda 3 (along with condensor/drier/expansion valve and a thorough flush and dry of all other lines and components.) It's cooling great, but there's a problem.

3 years ago I did the same to my Saturn Vue with a cheap replacement compressor, and it's still going strong with no issues. Encouraged by this, I ordered another cheapie for my Mazda. It's working great with the exception of the noise it makes when it kicks on (kind of like the ball in a spray paint can). The sound first showed itself during the initial refrigerant fill. With the compressor already engaged I slowly opened the valve to let in the refrigerant, and the minute I did I heard the sound.

Please see below for a link to a video of this noise.

I'm really hoping the sound could be in the clutch and therefore easy to replace, but I'm afraid I'll need to have the refrigerant captured again and send the who unit back. What do you think the sound is?

Thank you in advance for taking the time to read and respond.

https://youtu.be/oTZ7W3wZSq8

[Tim]

Neither one sounds great to me, especially via a YouTube video, and I'm not familiar with the pressures.

[JohnHere]

I'm concerned that you don't have the correct charge in the system, which might be the cause of the noise, along with a possible lack of oil. You did add the proper amount and grade of oil prior to recharging it, correct?

If you failed to evacuate the system, ensuring that it held vacuum, then recharged it precisely by weight into the well-held vacuum while monitoring the pressures using an accurate Manifold Gauge Set, then you probably don't have the correct amount of refrigerant in the system. Since you recharged it, presumably from just one small can containing only 12 ounces (at best), I'd say that the system currently is significantly undercharged. Hopefully, that can contained no sealer or other additives.

How could the compressor engage with the system empty of refrigerant? You must be mistaken about that.

The specs for your car call for 18 ounces net weight of R-134a, and 5.0 fluid ounces of PAG-46 oil. Since your car takes so little refrigerant, it's crucial to get the charge just right using the proper equipment for the system to run as it should.

What were the pressures, center vent temperature, and ambient temperature after you recharged it and ran it at ~1,800 RPM engine speed?

[genistas]

Sorry, I guess I should have included all that in my original post.

I removed the oil the compressor shipped with and added 5.5 oz of PAG46. The spec I read was that it called for 5.8, but I knew there was some residual oil in there.

I added 18 oz of R134A by weight, which was about 1.5 cans. And I was sure to bleed the line before opening the valve for each can.

I ran a vaccuum on it for almost an hour, and it got down to -29 PSI and held it there for another couple hours before proceeding.

The pressures at 90 degrees ambient temperature and 1500 rpm were ~40 low side, ~250 high side, which seem in-spec (if not slightly low)

I haven't completely ruled-out incorrect pressures, but I can tell you this. I added the first can with the compressor off. I then started the car and ran the A/C on max while I added the additional refrigerant. The sound was there when the compressor first kicked on under lower pressure and then went away. As I opened to valve to add more refrigerant, the sound came back while it was filling. So the sound existed at both low and normal pressures.

The temperatures coming from the center vent seem to vary between 40 and 46.

And maybe I explained it incorrectly, but I added the first can by just the vaccuum alone, THEN I turned on the A/C and got it up to 18 oz.

Thanks!

[JohnHere]

I removed the oil the compressor shipped with and added 5.5 oz of PAG46. The spec I read was that it called for 5.8, but I knew there was some residual oil in there.

Depending on what engine you have, the manufacturer's specifications (the specs that I have access to) call for either 5.00 fluid ounces for the 2.3L engine, or 5.08 fluid ounces for the 2.0L engine. For all intents and purposes, 5.00 fluid ounces for both is appropriate, as I mentioned previously. After all, who can measure 0.08 ounce (eight one-hundredths of an ounce) accurately. According to your plan, you should have added ~4.7 ounces to the compressor after draining it, making the amount you added ~0.8 of an ounce over specs, which is a small amount that probably won't affect the system's performance.

I ran a vaccuum on it for almost an hour, and it got down to -29 PSI and held it there for another couple hours before proceeding.

Good.

The pressures at 90 degrees ambient temperature and 1500 rpm were ~40 low side, ~250 high side, which seem in-spec (if not slightly low)

IMHO, I think they're too high. The low side should be near 30 PSI and the high side around 210 PSI at that ambient and with good condensing. At 40 PSI on the low side, the evaporator will be about 45°F, not nearly low enough for a comfortable cabin. By contrast, at 30 PSI, the evaporator will be around 35°F, which would be more in line with the 40°F center vent temperature you noted.

I haven't completely ruled-out incorrect pressures, but I can tell you this. I added the first can with the compressor off. I then started the car and ran the A/C on max while I added the additional refrigerant. The sound was there when the compressor first kicked on under lower pressure and then went away. As I opened to valve to add more refrigerant, the sound came back while it was filling. So the sound existed at both low and normal pressures.

I've heard noisy compressors like that before. It doesn't necessarily mean that your compressor is bad. It just might be "the nature of the beast." I would leave it alone and drive it for a few weeks. If the noise increases, then there's probably something going on inside the compressor. I don't think it's the clutch, though.

And maybe I explained it incorrectly, but I added the first can by just the vaccuum alone, THEN I turned on the A/C and got it up to 18 oz.

That's good, too. Now I get it

[genistas]

Well, thank you for taking the time to respond. It doesn't seem to be getting worse, so I won't worry about it for now.

Thanks again!

[JohnHere]

Hope I'm wrong, but I can't help wondering whether you finished charging it while holding the second can upside down. If so, that would mean liquid refrigerant was introduced into the running compressor instead of refrigerant gas. And because liquids can't be compressed, something inside the compressor would have given way.

If not the above, it just might be "the nature (sound) of the beast," as mentioned previously.