Buzzing AC compressor

A

A1an

Member
:
2006 Mazda 5 Touring
I remember my wife's old Mazda 3 had a pretty weak AC system. My 5 is pretty much the same (which sucks considering how friggin hot it is lately). What I cannot recall is if her compressor made a buzzing noise when the AC is on. I want to say it did but that was over three years ago since we sold that car. It isn't terribly loud and you can't hear it from inside the car.

It is a 2006 with 22k miles. Blows cold. No other issues.

Is this normal, something to worry about, or...?
 
does the buzz sound like something is loose, maybe a support bracket bolt is loose. May be something else under the hood has shifted and causing the buzz. All AC compressors make noise when cycling on/off, whcih doesn't help I know. If all the stuff under the hood looks good, and still buzzes, take it to a mechanic to be sure.
 
Let's say, for hypothetical purposes, that there is a problem. What are you going to do about it? If it blows cold it's not buzzing from a low charge, so you can't fix anything there. All you can do is check the charge, check the belt, and use it until it dies.
 
Give these folks a call or take a road trip over there since they are in FL.
www.polarbearinc.com

They are very friendly over the phone and will give you some suggestions to diagnose it. AC is one area I would not touch and really does require a specialist. I don’t think this forum will be able to help you much, rather ask this in a dedicated AC forum. I have read quite a lot in an attempt to fix another car (R12) but still afraid to touch it due to it being high pressure system and requires specific tools to do most work. In your case, my guesses are issue with the coil going out, clutch bearings going bad, or it might not your AC at all and instead the idler/belts.

As jimp commented, all compressors make a little bit of noise when the AC is cycled on and the clutch is engaged.
 
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A few months ago my refrigerator started making a buzzing noise when the compressor was engaged. I'm in the process of selling the house so I never did figure out what the deal was, but I'm guessing that the problem would be similar to your situation.
 
I'm pretty sure this is just how it sounds. My 2006 manual makes a slight but noticable buzz when the compressor engages, and my friend's 2006 automatic makes the same sound. I wouldn't worry about it unless it starts to get very loud or stops making cold air.
 
i'm interested in this topic because my brand new 2010 mazda5 is making a buzzing (more of a engine speed-sensitive "whirring" noise) whenever the compressor is engaged. it's definitely noticeable between idle and about 2500RPM. above that, the engine noise drowns it out. as far as i can recall, my 2006 mazda3 never made a similar whirring sound when the compressor kicked in. i have an apt with the dealer on wednesday to check it out... i'm going to be seriously bummed if they say this is normal, because it's actually quite annoying.
 
flcruising said:
You hear it while driving? That's not normal.
Click to expand...

yep, i started hearing it after about 1300 miles. with the stereo off and driving around at less than around 35 mph, it's definitely audible, and my wife has confirmed it. it sounds like either the compressor bearings are bad or the belt is to tight... nothing like a clanking noise, but more of a noisy bearing "whir" or "groan". it's especially annoying to hear it come and go as the compressor constantly cycles. i'll report back wednesday night after the dealer has looked into it. i'm hoping i didn't get a lemon... they're also looking into a highway speed vibration and a strange brake feeling... none of these were experienced with my 3!
 
so the car is at the dealer as i write this. they found the freon pressure to be low: 14 ounces versus the specific 22 ounces. they will see whether recharging the system resolves the whirring noise. if not, they will replace the compressor.

the bigger question i have is, why is the pressure low on a brand new car? either it was never properly charged, or there is a slow leak.
 
Huh? They told it had 14oz? I'd love to know how in the world they determined that! Did they evacuate the system and pour out the oil? I highly doubt that.

Anyways.

Did you have cooling problems too? You never mentioned that. If the system were low on refrigerant, you'd know. Or has it not been warm enough where you're at to run it constantly?
 
ha, it's been plenty warm, with a high of 97F yesterday. cooling has been superb, better than the mazda3. it all sounds sketchy to me as well... my money is on a faulty compressor... OR... low freon pressure caused damage to the bearings to cause the noise from insufficient lubrication, if that's possible. i'm not a refrigeration expert...

EDIT: another update. service mgr has informed me that adding freon has "reduced" the noise slightly, and that it now sounds identical to three other new mazda5s on the lot. so he's trying to pass this off as normal for this car. i won't know what "reduced" sounds like until i pick up the car, but i'm not too confident i'm going to be satisfied.
 
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Sounds sketchy. I've never heard a compressor making more noise by being undercharged. Overcharged yes, not under. And yes, defintely from low oil charge, but adding refrigerant obviously doesn't add oil, so they may have just added oil. Who knows, maybe the factory didn't put enough oil in the system to begin with? Only way to find out though is to evacuate and drain the system.

What they could have done is checked the pressure, saw it was low, and added 14oz. of refrigerant to bring it back up to pressure. But 14oz loss in a 22oz system would have definitely effected the performance.

Could you upload a youtube with some audio of it?
 
If its low on refrigerant, the noise must be cavitation when the refrigerant cycles through the system.
 
well, i got the car back and it's no better. they evacuated the system and recharged it to spec. they claim it's somewhat "better" and that it sounds identical to the other new mazda5s on the lot. basically they're saying it's just the nature of the beast. i picked it up after closing, so i couldn't question the service manager, but it still sounds the same to me. maybe i'm ultra-sensitive to noises and i pick up on things that other people would never bother to register in their consciouses. interestingly, the loaner car i had for the day was a 2010 mazda6 with the base 2.5L 4 engine, and i could *barely* detect the compressor cycling on and off. i should have asked if they had any 5's to loan out, but i didn't think of it.

i think the next step is to demo some other new 5's and compare for myself...
 
I have to wonder if it's not related to belts. My 5 has always made some strange noises, even the day it drove off the lot with 0 miles on it. The belts actually got quieter over time, but every now and then I hear some kind of weird noise and get under it to find it's just the belts.
 
Robotaz said:
I have to wonder if it's not related to belts. My 5 has always made some strange noises, even the day it drove off the lot with 0 miles on it. The belts actually got quieter over time, but every now and then I hear some kind of weird noise and get under it to find it's just the belts.
Click to expand...

that's a good point, and i've also heard strange belt noises, especially after rain. usually the noises go away once the engine is warmed up and the belts have dried. maybe in this case, the belt is just tight, and needs to loosen up a bit.
 
Mine just freeze up today, now I need a new one after my warranty expire in June. This sucks! I call mazdausa and they said to just pay dealer to fix it ( 2000 or more ) Now I'm in the hunt for new parts and find someone to do it for me for about 1000 bucks. I only got 48000 miles on it.
 
southpawboston said:
well, i got the car back and it's no better. they evacuated the system and recharged it to spec. they claim it's somewhat "better" and that it sounds identical to the other new mazda5s on the lot. basically they're saying it's just the nature of the beast. i picked it up after closing, so i couldn't question the service manager, but it still sounds the same to me. maybe i'm ultra-sensitive to noises and i pick up on things that other people would never bother to register in their consciouses. interestingly, the loaner car i had for the day was a 2010 mazda6 with the base 2.5L 4 engine, and i could *barely* detect the compressor cycling on and off. i should have asked if they had any 5's to loan out, but i didn't think of it.

i think the next step is to demo some other new 5's and compare for myself...
Click to expand...

Anton, my MZ3 has the same sound and when I had the car on the hoist, the compressor is actually mounted to the car body as well as the engine with a rubber bushing. I thought too that something was amiss, but I can see why now it is like that.
 
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