A/C Compressor Noise (Page 1/2)
chaotichamster9 AUG 12, 05:14 PM
So recently I charged my old A/C system with R12 (confirmed as r12 not freeze 12 or a derivative). It’s been over a week and it’s still blowing cold. However, I have noticed that occasionally I will hear a screech sound coming from out back. I cut the A/C and the noise stops, then after a break it will go back to working normally again. Is this the sign of a failing compressor or one that is low on mineral oil? The fact that it’s been blowing cold this long is more of a surprise to me, if I have to i will be doing a full conversion to R134a with new pieces. Filled with 2.5 lbs of r12 by the way.
FX AUG 12, 05:32 PM
Usually a screeching sound is the compressor clutch. If the compressor was not working long enough, the clutch may have gotten rusty, that may be the noise, and it should go away on it's own...If not, you may need a new clutch. I don't think the compressor itself would make that kind of noise...You probably put a little oil in it when you charged it, right?
Mike in Sydney AUG 12, 05:50 PM
A/C compressor belt tight enough? They are a pain to tighten. You can try using a belt dressing (prestone and other make it) to see if the squeaking stops but that's a temporary fix. I'd check the belt tension and go from there...

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Mike in Sydney

chaotichamster9 AUG 12, 06:24 PM

quote
Originally posted by FX:

Usually a screeching sound is the compressor clutch. If the compressor was not working long enough, the clutch may have gotten rusty, that may be the noise, and it should go away on it's own...If not, you may need a new clutch. I don't think the compressor itself would make that kind of noise...You probably put a little oil in it when you charged it, right?



Another note, when I first put it to the “max A/C” setting after the charge it did squeal then went away and hasn’t made a noise on that setting since. The squeal i mentioned in my first post occurred after I used the “normal A/C” setting for the first time. Perhaps this is just the clutch breaking loose after spinning on a different setting for the first time(as it did with max A/C)? As for oil, unfortunately we did not, I wouldn’t know which one/how much/or where to buy it for an old R12 system.

[This message has been edited by chaotichamster9 (edited 08-12-2019).]

RWDPLZ AUG 12, 07:41 PM

quote
Originally posted by chaotichamster9:

As for oil, unfortunately we did not, I wouldn’t know which one/how much/or where to buy it for an old R12 system.




Oil for R-12 is 525 viscosity mineral oil, NAPA seems to be the most consistent place to get it (or online), Fiero system total capacity is 8 ounces.

Squealing is likely loose belt, old belt, cheap belt, compressor clutch air gap too large (should be ~0.020), or compressor clutch and pulley too rusty to make good contact when the magnet engages. If the noise just started after a week, probably belt related.
chaotichamster9 AUG 12, 10:47 PM

quote
Originally posted by RWDPLZ:


Oil for R-12 is 525 viscosity mineral oil, NAPA seems to be the most consistent place to get it (or online), Fiero system total capacity is 8 ounces.

Squealing is likely loose belt, old belt, cheap belt, compressor clutch air gap too large (should be ~0.020), or compressor clutch and pulley too rusty to make good contact when the magnet engages. If the noise just started after a week, probably belt related.



Ok I can see if my local NAPA has some. How exactly do I add it to the compressor and is there a way to tell how much is in there already? I don’t want to overfill it. Had the A/C running for around an hour earlier after my first post and no more noises so maybe it’s worked out the kinks. I do hear like a buzzing coming from around the drivers side air vents (?) I’ve just chalked that up to regular noises of the A/C running but it is a bit annoying.
FX AUG 13, 02:28 PM
When A/C is on max, all it does is recirculate the cabin air. It makes no difference to the compressor...If you can find a a can of that oil that you can put in through the low side valve, I would do that, no more that 3-4 ounces. If you can't find a can, unfortunately you'll have to evacuate the system, open a line, preferably at the compressor, pour the oil in from a bottle, and recharge the system...If you can't find the oil locally, check eBay...

[This message has been edited by FX (edited 08-13-2019).]

chaotichamster9 AUG 14, 09:04 AM

quote
Originally posted by FX:

When A/C is on max, all it does is recirculate the cabin air. It makes no difference to the compressor...If you can find a a can of that oil that you can put in through the low side valve, I would do that, no more that 3-4 ounces. If you can't find a can, unfortunately you'll have to evacuate the system, open a line, preferably at the compressor, pour the oil in from a bottle, and recharge the system...If you can't find the oil locally, check eBay...




I will see if I can find a bottle of that mineral oil and add the 3-4 oz. I’ve driven another 60 or so miles and it’s still blowing cold, no more squealing and I can hear the compressor clicking on and engaging as it should, albeit a little frequently, not sure if that’s because it needs the oil or if my charge is running low?
FX AUG 14, 10:33 AM
If the compressor is cycling, that would indicate a low charge. If the screeching is gone then it could have very well been a rusty Clutch that cleaned itself up...Do some research to see what kind of oil you should use. Since the system seems low on juice, you should be able to find a can of freon, with an oil charge in it, and just add it to the low side without having to open the system...I just checked eBay for you, but I don't know how to copy the link. The R12 is pricey, but available with oil. Check it out...

[This message has been edited by FX (edited 08-14-2019).]

chaotichamster9 AUG 14, 12:17 PM

quote
Originally posted by FX:

If the compressor is cycling, that would indicate a low charge. If the screeching is gone then it could have very well been a rusty Clutch that cleaned itself up...Do some research to see what kind of oil you should use. Since the system seems low on juice, you should be able to find a can of freon, with an oil charge in it, and just add it to the low side without having to open the system...I just checked eBay for you, but I don't know how to copy the link. The R12 is pricey, but available with oil. Check it out...




I appreciate you checking eBay. I’ve done some reading and it seems that adding oil is really recommended for when you are replacing A/C components. My system is all original, no replacements so perhaps it doesn’t need the oil? Another small note I popped the front hood and see that the accumulator is pretty sweaty, is that normal?