AC Rattle at 2-2.5k rpm
 

I have this weird rattle when I have my ac on only at certain rpm’s. From 2-2.5k if the ac is on I hear a buzzing/rattling noise from the engine…. Any clues? I’ve replaced the belt tensioner, have new belts….

I did rebuild the car after I bought it from the insurance auction and I replaced the compressor and added 5fl oz of pag oil as well as 14fl oz of r134a. I also added in another 6ish fl oz during the summer because I thought maybe I didn’t add enough Freon when it was 110 degrees out but found the ACs on these kinda suck

https://youtube.com/shorts/7DXuphqyS...p1-agCoAqwNSai

Can we assume that you prepped and charged the system properly?

That's why I tell people not to DIY AC, it's already a pain to deal with in a pro setting.

Did you replace components other than the compressor? New/rebuilt compressors usually have more oil in them than needed. You usually drain the old compressor into a measuring cup, note the quantity, drain the new compressor and add back the same amount that you drained from the old one.

If you put in the compressor as-is + 5oz, and did you pull a vacuum before filling? Your system might be massively overfilled in oil, which is a massive pain in the butt to rectify and already a great debuff on performance, but it may also have worse performance on top of that from an improper fill without a vac pump.

Further, What did you use EXACTLY to fill the refrigerant? Pure, unadulterated r134a or DIY bottles with "additives"? Those contain hydrocarbons and leak sealers that contaminate and clog modern condensers, which have much smaller passages than the old stuff they're intended to fix.

Welcome to the forum. I can appreciate your DIY attempts. -:thumbsup:

However, I have found out over the past 70 years of DIY tinkering with cars, when it comes to the AC, it's best left to the professionals.

(Bubba says, in the PNW, you don't need the AC below 2500 RPM anyway, just leave off till you get up to speed - ;))

BTW, I was thinking back and I think I should expand a bit on my no-DIY stance on AC:

I'm not telling anyone to not repair their AC system themselves, you are allowed to, for example, change a compressor, condenser, and if you feel like taking out your dash, even changing the evaporator. But holy crap, please please please! have a professional 1) recover and empty the system before you do your work and 2) have a professional correctly leak check, evacuate and charge the system afterwards.

For example, If you did it yourself and your system is now overfilled in oil by 7 ounces, the cost and hassle of rectifying that will wipe out all that you've saved DIYing the job in the first place. You can't just "empty oil" out of an AC system, there's no drain plug, you have to crack the seals in multiple spots, backwash it with solvent until all the oil is out and then add the correct factory fill of oil. You don't want to have to do that.