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I’ve seen some threads on here about loud AC compressors, but none seem to end up with a solid resolution, so I figured I’d ask myself.


About 2-3 weeks ago, suddenly, I noticed that with the AC set to a fairly cold temperature, or at least a temperature much lower than the outside temp (if you live in Chicago, you know it’s been sporadically very hot here this month) - I could hear a loud groaning sound that correlated exactly with RPMs and went away with the AC off.

Now, we did go from what must have been the longest winter in history (almost no spring to speak of, temps went from consistent 30-50 degrees to 70-80 almost overnight) straight to summer, so it’s been a while since I’ve used the AC before the last few weeks. However, it never did this before. And, frankly, even during some of the warmer days in April & May when I was certainly using the AC (although not as heavily) - I did not hear anything at all. This seems to have been a sudden occurrence.

I have also thought lately that the AC could blow colder - I hadn’t thought this before, but today, while driving around, even with the system set to max AC, it seems like I remember it being much colder even a year ago.

I’m wondering (and hoping) that this means it might simply need a recharge? As far as I know, this car hasn’t ever had one, and it’s a decade old now...so seems reasonable that this might be the case. However, the loud compressor also often seems to be a sign of failure, although it seems strange that for a purely mechanical part, it would suddenly become so loud and not gradually become worse & worse.

Will probably buy a recharge kit just to see, hoping that takes care of it. Thanks.


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If you don’t remove the air from the system you will cause more damage to compressor, problem with diy from auto parts store is it just adds freon. so now the ac compressor has to compress something it’s not designed to. these dyi recharge kits make repair shops tones of money. Just a FYI
 

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If you don’t remove the air from the system you will cause more damage to compressor, problem with diy from auto parts store is it just adds freon. so now the ac compressor has to compress something it’s not designed to. these dyi recharge kits make repair shops tones of money. Just a FYI
Err... what 'air' are you talking about? OP system has not been opened if that's what you're referring to. And what do you think the compressor was designed to compress? (Freon has been banned for 20+ years btw, but I get your point).
 

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Discussion Starter #4
I’m hoping there’s not any air(atmospheric)...as far as I can tell there shouldn’t be a leak of any sorts, although I can’t confirm. Although in a pressurized system there really shouldn’t be any even if there is a leak, right?

I will say, for the last 3 weeks that I’ve been noticing this...things haven’t really progressed....the sound hasn’t gotten worse, the AC temp hasn’t gotten any warmer...AC systems have always seemed like black magic to me, is it reasonable for a system that needs to be recharged to change so suddenly? That’s the only thing that worries me.


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I’m hoping there’s not any air(atmospheric)...as far as I can tell there shouldn’t be a leak of any sorts, although I can’t confirm. Although in a pressurized system there really shouldn’t be any even if there is a leak, right?

I will say, for the last 3 weeks that I’ve been noticing this...things haven’t really progressed....the sound hasn’t gotten worse, the AC temp hasn’t gotten any warmer...AC systems have always seemed like black magic to me, is it reasonable for a system that needs to be recharged to change so suddenly? That’s the only thing that worries me.


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Take it to a reputable shop for UV leak test/proper recharge with the equipment that evacuates the system. The canned R134a kits you get off the shelf wont fix a fault with the AC system just pump in more refrigerant and oil (some have "stop leak" chemicals). The canned refrigerant added to the system will leak from bad seals, if that is the problem. If bad seals arent the problem, then adding more refrigerant (and oil) will be detrimental to the compressor.

I dont work on AC systems either, so this is something I always hand over to a shop. Worth every penny on 90F+ days.
 

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I’m hoping there’s not any air(atmospheric)...as far as I can tell there shouldn’t be a leak of any sorts, although I can’t confirm. Although in a pressurized system there really shouldn’t be any even if there is a leak, right?

I will say, for the last 3 weeks that I’ve been noticing this...things haven’t really progressed....the sound hasn’t gotten worse, the AC temp hasn’t gotten any warmer...AC systems have always seemed like black magic to me, is it reasonable for a system that needs to be recharged to change so suddenly? That’s the only thing that worries me.
In practice no. Technically yes due to diffusion across the rubber hoses etc. The proper way to recharge is to apply vacuum to the system, make sure no leaks exist, then recharge by refrigerant WEIGHT. Addition of oil depends on what's going on. I have NEVER seen any shop fill by weight so I tend to be skeptical. Most / all only hook up gauges and guesstimate by pressure readings.
 

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Err... what 'air' are you talking about? OP system has not been opened if that's what you're referring to. And what do you think the compressor was designed to compress? (Freon has been banned for 20+ years btw, but I get your point).


If your system is leaking freon what do you think replaces it?
Edit: r134a is a refrigerant just like r12 so both typically are called “freon”. And if the shop you go to doesn’t use a scale to weigh r134a does that means their using cans? Not a true ac shop then, my shop uses hundreds of pounds of 134a a summer and every ounce is weighed...
Btw. You can still purchase r12 and it’s still being manufactured.
 

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I’m hoping there’s not any air(atmospheric)...as far as I can tell there shouldn’t be a leak of any sorts, although I can’t confirm. Although in a pressurized system there really shouldn’t be any even if there is a leak, right?

I will say, for the last 3 weeks that I’ve been noticing this...things haven’t really progressed....the sound hasn’t gotten worse, the AC temp hasn’t gotten any warmer...AC systems have always seemed like black magic to me, is it reasonable for a system that needs to be recharged to change so suddenly? That’s the only thing that worries me.


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It’s not magic, it just need to be recharged. Sorry for running off the topic, everyone has basically told you the same thing. Have it professionally done by a reputable shop and you should have no problems for years or invest in the right tools to do it yourself with possible same result. DO NOT buy those “dreamer” recharge cans from auto parts store, they are intended for short term use and can lead to system failure.
 

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Discussion Starter #9
Guys, thanks for all the replies.

I'm in the habit of doing the work on this car myself when I can...however I'm not sure what else one would need for a proper recharge...I've only ever seen people use the cans one might buy from an auto parts store, one with a pressure gauge to ensure proper filling, and that's about it.

If I had a leak, wouldn't I quickly be down to ~no AC at all? I suppose not if it was slow...but given that it's been nearly a month, with lots of AC usage in that time, it seems as if I'd know if it was leaking out at any sort of noticeable rate.
 
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