Second Compressor Also Buzzing/Clicking loudly

[peanutaxis]

Hi,

Thanks in advance!

I've had my Mazda 6 2006 for about 8 years. The AC pump started clicking a few years ago - though the AC worked fine - and got louder and louder. Eventually it stopped blowing cold and shortly after it seized (I feel like it overheated and then the bearing failed) so I replaced the pump (with a second hand one), talking care to try to put in the same amount of oil that came out of the original one. A few AC uses in and the replacement pump is making EXACTLY the same noise as the first did - and the AC still works too, just like with the original pump. So it looks like a carbon copy problem.

I notice that when I first put the AC on the pump doesn't make any noise but gets louder and louder which makes me think that maybe there isn't enough oil in the system.

Any suggestions are very much appreciated.
p

[Cusser]

so I replaced the pump (with a second hand one)

A used AC compressor is a huge gamble. New compressors are available for this Mazda, depends on which engine you have:
https://www.ackits.com/comp-dks17d-4478

https://www.ackits.com/comp-dks17d-pv6-12v-4671

[JohnHere]

I agree with Cusser.

Some additional thoughts: If your original compressor seized up, it was probably due to a low refrigerant charge, running the system that way, and consequently, oil-starving the compressor. The refrigerant carries the oil, and lack of lubrication equals a seized compressor.

Sounds to me like the "new" compressor is also on the verge of seizing-up because you probably didn't replace the condenser/receiver-dryer assembly and thoroughly flush the remaining components, which must be done following a catastrophic compressor failure to clear remaining debris and contaminated oil from the system.

You also most likely have a leak or leaks somewhere in the system.

I don't know how you recharged it, but without the correct tools and *pure* R-134a (containing no additives and/or sealers; UV dye is okay), plus new PAG oil, you probably didn't get the charge and oil just right.

Sorry, but it appears you'll need to start all over again, or have a professional shop handle the repairs.

[peanutaxis]

I agree with Cusser.

Some additional thoughts: If your original compressor seized up, it was probably due to a low refrigerant charge, running the system that way, and consequently, oil-starving the compressor. The refrigerant carries the oil, and lack of lubrication equals a seized compressor.

Sounds to me like the "new" compressor is also on the verge of seizing-up because you probably didn't replace the condenser/receiver-dryer assembly and thoroughly flush the remaining components, which must be done following a catastrophic compressor failure to clear remaining debris and contaminated oil from the system.

You also most likely have a leak or leaks somewhere in the system.

I don't know how you recharged it, but without the correct tools and *pure* R-134a (containing no additives and/or sealers; UV dye is okay), plus new PAG oil, you probably didn't get the charge and oil just right.

Sorry, but it appears you'll need to start all over again, or have a professional shop handle the repairs.

Thanks for the help!
In my experience and estimation low refrigerant on its own shouldn't be a problem. I say this because there must be millions and millions of cars out there that lose gas over time (just as several of my cars have over the years without problem) and it's just not a thing you hear: "my ac pump blew up because the refrigerant was low". I've never heard anyone I've ever known say this. So I think that having to get everything *just* right is not necessary.

But you are completely correct that I haven't done things properly which is not ideal. You are right, of course, that symptom-following like this is the solution for the hacks where doing things properly would solve the issue. Even so, as a hack!, I love learning about these technical things and problem-solving and I am curious that EXACTLY the same symptoms are present with another pump and so I was curious to reach out and see what others though.

Thanks,
p

[JohnHere]

According to the A/C specifications that I have, your vehicle calls for the following: 16.8 ounces net weight of R-134a, and 5.1 fluid ounces of PAG-46 oil. The under-hood decal, if it's still there, might differ slightly. If so, the decal always takes precedence.

Compared to older vehicles, as well as vehicles having front and rear A/C, this system holds very small amounts of both refrigerant and oil. If the A/C system ran repeatedly with a low charge, it wouldn't take much to "starve" the compressor for oil, which in my humble opinion is what probably happened. Thus, you had a catastrophic compressor failure, or seize-up.

Additionally, the following crucial steps were apparently skipped: Replacing the condenser/receiver-dryer assembly and thoroughly flushing the other components, thus removing any debris and contaminated oil remaining in the system from the seized compressor. Neglecting these two steps could explain why the replacement compressor is now making noise, and it's probably on its way out as well.