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When to Change A/C refrigerant oil

I have had 2 japaneses cars that developed siezure of the A/C compressor after the car had 160,000 miles. Now I want to know if its advisable to change the refrigerant and A/C oil before that happens in my 1998 Lexus LS400 that now has 150,000miles?

There’s no advantage in doing this. It would require reclaiming the refrigerant, disassembling the A/C system, sweeping/flushing every component, adding oil to every component, reassembling the system, evacuating the system, and recharging the system. What I just described is what’s done when a compressor fails. So wait until it fails. If it ever does.


I would ask my AC specialist. I know we are running a Corolla that is 14 yrs old and has never lost any refrigerant. It still cools just fine. So far, the “if it ain’t broke, don’t fix it” approach has worked for this AC unit.

160,000 miles and 10 years is a decent life expectancy for an A/C compressor. There are very few things you can do that will make the new one last any longer than the original. One thing you could do is make sure you run the air conditioner every once in a while during the winter months to keep the parts from seizing. If it is another 10 years before you need a new compressor, I think you will do quite well. It is an expense that might shock your budget, but spread over 10 years, it comes out to about $0.36 per day.

At that mileage the compressors probably seized due to lack of oil and one should not need to change the compressor oil at all. With age/miles air compressors will normally lose some refrigerant and with that refrigerant loss there will be oil loss also.
The usual suspect for refrigerant, and compressor oil loss, is the compressor shaft seal.

In many cases, when a system is topped off or recharged with refrigerant the oil is either omitted or completely forgotten about. The addition of an ounce or two of oil can prevent a compressor seizure.

The last time I looked at a can of automotive refrigerant at the store (I think it was last summer.), it had the oil in it.

Run-of-the-mill refrigerant does NOT contain oil, but you can buy some that does.

Absolutely don’t want to do this - more chance to mess it up than help. Anyway, 150k of wear’s been done by now, changing it wouldn’t help.

What you say above is not what was done on either of my old cars. You are out of touch with reality. In both of my previous cars, the old compressor was removed and the the new one mounted with new compressor oil in it…nothing else was done in either case and the new compressor worked for the next 50,000+ miles without a problem in both cases.I believe the compressor oil deteriorates over time and adding 1-2 oz. of new compressor oil at 150,000 mile mark will prevent the compressor siezure perhaps for another 100,000 miles.!!! thats my opinion.

OK4450 - I think you are correct!. Adding 1-2 ounces of new (ND-8)compressor oil at the 150,000mile mark may well replace the slow loss of
compressor oil from the system in the past and may well prevent a Compressor siezure for another 100,000 miles. The loss through aging of the compressor shaft seal will continue to get worse with time and in the end will be the cause of compressor seizure in my opinion. Unfortunitly, the driver handbook makes no reference to proper maintenance of the A/C system with regard to need for new compressor oil requirements at 150,000+ miles or at any time during the life of the car.

They make no provisions for it because it is assumed (Ha!) the compressor will outlast the car. Generally speaking, around the 7 year mark is when A/C leak problems start developing. I don’t like using stop leak products but some refrigerant is available with oil and a seal conditoner (as opposed to a stop leak product) in it. Depending on the type of seal, the severity of the leak, etc., the conditioner may stop or at least slow down a leak.

One can usually tell if the compressor shaft seal is the problem by examining the bottom edge of the compressor around the clutch assembly. If it’s pretty oily and grimed up then you can figure the shaft seal is leaking.
The shaft seal can actually be replaced without replacing the compressor. Most seal kits run about 15-40 dollars depending on the car and model.

Some shops may be leary about doing this on a high mileage car because they assume that if a seal kit does not hold or another A/C problem develops they will get blamed for cutting corners or something and the customer will hold them liable.
Replacing the seal kit is a viable repair if the compressor is not noisy, although the standard practice is to replace the compressor and make sure they’re workigg with a clean slate so to speak.

I had a slight refrigerant leak on my Lincoln about 1 and 1/2 years ago and simply added a can of refrigerant with oil and conditioner. It’s still working fine. The compressor is buried deep, it’s putting out ice cold air, and I just haven’t felt like devoting the time to wrestling the compressor out and replacing the seal kit.
If and when it becomes critical I’ll worry about it but a can of refrigerant every other year is much easier. :slight_smile:

Ok4450 Where do I find a seal kit?? Autozone? what web site offers the seal kit for the A/C compressor of my LS400?

What do you mean out of touch with reality??? Your original post asks whether you should change the refrigerant and compressor oil. What tester told you is exactly right. Under normal operating conditions, you should never have to add oil or refrigerant to the system. If the system develops a leak, as most systems do, there will be refrigerant loss and probably some oil loss. Dont just go throwing oil in there just to be adding oil. Too much oil is not good for the system either. It mixes with the refrigerant which is constantly changing back and forth from a gas to a liquid. The oil is not going to evaporate. This is a closed system. If you are having substantial loss of oil from the shaft then adding oil would be advisable otherwise if the system is cooling and there is no sign of oil leaking, leave it alone.


Then my friend, whoever replaced the compressor without sweeping/flushing the A/C system got very lucky! When a compressor fails it usually causes what is called “Black Death”. This means the oil has been burnt in the system and there’s probably debris from the failed compressor in the system. Failing to sweep/flush the A/C system to remove this burnt oil/debris will result in failure of the new compressor. So I’m not out of touch with reality. This is the way all A/C systems are repaired when a compressor fails. Whether it’s a mobil or stationary A/C system. It’s a standard in the A/C repair industry.


Now you’ve changed your question. Would it hurt to add 1-2 oz. of compressor oil? Probably not. You asked about changing the oil and refrigerant, something you should NOT do.

Well there you go! The OP can get the refrigerant replaced with new refrigerant that contains oil. Then he doesn’t need to worry about how much oil to use. Doing this once every ten years might not be a bad idea.

They show 2 different compressors with slight variations in the seal kit. Here’s one for an example.

Changing the seal kit usually requires a few special tools and a pair or two of snap ring pliers. The special tools can often be used for free as part of some auto parts stores “tool loaner program”. Put up a deposit, use the tools, and get your money back when you return them.

I’m not familiar with the location of the compressor on your particular model of car but it’s often easier to remove the compressor if it’s buried somewhere. On some cars the compressor does not need to be removed; the seal kit can be changed with the compresor in place. Most compressors are kind of a pain in the neck to access though.

(This kind of goes along with my theory of why oil loss can be worse on some models than others. Many compressors are mounted low on the engine and when the compressor is not being used refrigerant oil will have a tendency to pool in the lowest parts of the system. This means the compressor and the condenser. When at rest the system (properly charged) will usually have a static pressure of around 115 or so PSI. With oil settling in the compressor and 115 PSI being applied constantly you can see how this can cause refrig. oil to ooze out over time.)

In the old days most air compressors were mounted up top and the compressor was the highest point of the system. Replacing seal kits on the top mounted compressors was a pretty common occurrence.

Hey, Transman, you reccomended that I use Barryman B 12 in my 96 Dodge van some time back. Well it is still doing fine and my son-in-law did the same with his '94 and it helped it. Thanks again. However that same van has been giving me trouble for 2 years. anytime the gas gets down to 1/4 tank it cuts up and will barely run. 2 weeks ago I put a new coil on it and yesterday I had a new fuel pump w/filter installed and today it cut up with me again. Any Ideas?

Settle down a bit here. Tester and Transman are correct. If someone only replaced the compressor without doing anything else (especially the accumulator) then you were indeed very lucky. Your luck could have been helped along IF the compressor was not trashed and was replaced simply on the basis of a seal leak.
If the compressor was trashed then you were extremely lucky and if it was a matter of a minor seal leak (not noise) then you should ask the shop why they didn’t replace the seal instead of the compressor.

As mentioned, you don’t want to over oil a compressor either. This could cause an “oil log” (that’s what I call it anyway) and in this case the compressor is not able to move that much oil quickly. This can cause valves to blow in the compressor.

If your previous shops were replacing the compressor without flushing, new accumulator, etc. then you should not use them again. Matter of fact, any time an A/C is inoperative for a while or has been opened the accumulator (drier if you will) is always replaced.

Are your compressors siezing or exploding? (broken parts). You know neither the factory nor the dealer nor the customer would ever pay for a system flush,and a customer was never warned “no flush” no warranty.Now I would like to flush also but I would also like to be paid for the extra time to flush.