How to get right amount of oil in AC system?

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I have a 2006 Mazda 3 2.3L, with an ac compressor clutch that's basically falling off the compressor. They system actually still works (though it's not as cool as it should be). The compressor did not seize. But obviously I can't have a clutch that's rattling around. I tried to replace the clutch, but just couldn't ge the right part (it's not the original compressor). So I'm going to replace the whole compressor and the drier while I'm at it. I also have a small leak in the high pressure hose, so I'm going to replace that.

My question is. How do I make sure I end up with the right amount of oil in the AC system? I know I'm supposed to drain the oil out of the old compressor and make sure the same amount is in the new compressor. But I don't know how much oil leaked from the high pressure hose or how much might be in the drier. So how can I be sure I have the right amount in the system when I'm done replacing parts?
 

cb474

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Thanks. Any advice on how to do this if I don't take the whole system apart, but rather just replace the compressor and drier?
 
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You can measure the amount of oil that is on the old compressor and adjust the level on the new compressor it.

You can also do a search of how much oil to add when replacing other components.
 

cb474

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Thanks. As I mentioned, the high pressure line is leaking, which I plan to replace. It has some oil residue on it. Should I be concerned about how much oil might have leaked out with the refrigerant? Or would that be too little for it to really matter?
 
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Thanks. As I mentioned, the high pressure line is leaking, which I plan to replace. It has some oil residue on it. Should I be concerned about how much oil might have leaked out with the refrigerant? Or would that be too little for it to really matter?
The amount that went out the hose is very minimal. I would drain the old compressor and let me know how much you got out. Are you changing the reciever drier too? Is it a bag or a metal cyl?


Edit: I looked at the reciever online. I would add 1 oz of oil for that. I would add 1/2 oz for the leaking line. Then measure what I got out of the compressor+ another 1/2 oz.
 
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The last time I did it, I search online and it showed up with a table of how many ounces of oil it needs.
There are specific Car AC forum that has the data for all sort of cars.
 
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I've replaced compressors on a 96 Mustang gt and a 2006 ford explorer, I did a Google search and both turned out to be around 3-4 ounces.
The mustang compressor I purchased new from O'Reilly about 5 years ago, ran good for about a year until I sold the car.
The explorer I just replaced about a month ago with a junkyard one, it is also running fine so far.
I was looking at rockauto for compressor prices for the explorer and most of them stated that they are preoiled.
Good luck.
 
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you should use a vacuum pump to evacuate the system prior to filling. If you do, adding oil is really easy. Just put a 3-4 inch section of clear vinyl hose over the high pressure port and fill it with oil. Then use a small screwdriver or rod to gently depress the schrader valve. The oil will go right in. Just be careful not to introduce air. Repeat as required until you’ve put 5 ounces in.
 
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I know one method says to drain the old compressor and only put back in that amount, but what if you leaked a bunch from your compressor? I'm sure I did! So I just put in what the compressor calls for and I otherwise don't worry about it. Seems like several other people are doing the same.
 
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I know one method says to drain the old compressor and only put back in that amount, but what if you leaked a bunch from your compressor? I'm sure I did! So I just put in what the compressor calls for and I otherwise don't worry about it. Seems like several other people are doing the same.
Having an excessive amount of oil will effect cooling. But I mean lots. An extra ounce or 2 won't hurt anything. Having too little will burn the compressor up.
 

cb474

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Thanks to everyone for the thoughts on this.

The amount that went out the hose is very minimal. I would drain the old compressor and let me know how much you got out. Are you changing the reciever drier too? Is it a bag or a metal cyl?


Edit: I looked at the reciever online. I would add 1 oz of oil for that. I would add 1/2 oz for the leaking line. Then measure what I got out of the compressor+ another 1/2 oz.

Thanks for the suggestion. Can I add all of that together directly to the compressor (because it will get circulated through the system)? Or should I add 1 oz directly to the drier through one of the ports where the lines connect?
 
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When I had to deal with adding oil to an AC system, because the %#$% springlock fitting that didn't want to come apart when I wanted it to later decided to blow apart as I was charging the system spraying oil everywhere and wasting about $15 of R134a, I just guesstimated how much oil was dripping off of everything under the hood and poured that much down the hose that blew apart.

I must have guessed right because it's probably been at least 50K since that and it's still working fine...
 
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This is the forum I have been going to since 2006 and have learned a ton of information. I have also bought quite a few parts from the online store associated with the forum.
I went to the same forum and read all I could before rebuilding/converting the system in the Lumina in 2011 (compressor failure = Black Death). The car is falling apart and ready the scrap yard but the AC still runs frigid.
 
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The R134a currently in the system needs to be removed and saved before you open up the system. Even though R134a does does not effect the ozone layer, it's still a greenhouse gas and a cause of global warming.

You need to pull a vacuum and make sure the system can hold it for an hour.

Then fill the system by weight.
 
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