Upcoming project A/C

LARRYDLTN

MEMBER
2000 CHEVROLET IMPALA
3.4L
6 CYL
2WD
AUTOMATIC
200,000 MILES

I failed at educating myself. Two similar cars swapped compressors due to running car locking up. The system was open for 30-45 minutes. Previously running cool, not cold, but adding 134 every few weeks.
Swapped compressor ran great for 4 days after only can recharge, no vacuum on system, then just stopped. Car thinks it's running by RPMs still raising, don't think fan is running at same time, but was while running.
Fixing to get gauge and pump set recommended, and compressor/drier kit from Rock Auto.
Was wondering, new compressor will be loaded with 3oz oil and additional 8oz. If I were to just try and vacuum a system only replacing the accumulator/drier filter to check if old compressor still works, what to look out for or recommendation on trying to test fire the old compressor, maybe even with system open to make sure it's not locked up. Also, does vacuuming a system remove the refrigerant oil if the compressor is at bottom of motor and not removed?
Thank you

5 Replies

KASEKENNY

MECHANIC
18,907 POSTS

I think you are on the right path, but I would suggest a couple of things first.

To start we need to check the pressure of the system to find out if this is needed. Clearly, I think you are correct that we need to pull the system into a vacuum, but we want to start by checking the pressure.

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

The system is pulled completely empty of freon and oil so you will need to be sure to put the amount of oil you remove back in.

However, if you are not replacing components then you only add back in the oil that was removed as the compressor and accumulator will hold oil in it.

If you are replacing something, then you need to add the proper amount of oil in for that component. As you said, most compressors come with oil already in them so you don't need to do that, but you do need to make sure it is not a dry compressor.

So, take a look at the guide above and let's get the pressures before you open the system and then pull it into a vacuum and make sure it holds a vacuum to confirm there are no leaks.

I am attaching the chart below that will help with checking pressures.

Let us know what you find, and we can go from there.

Thanks

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Thursday, June 16th, 2022 AT 9:27 AM

LARRYDLTN

MEMBER
3 POSTS

Thanks for the response!
Seems I left out an important detail! LOL
I'm not "sure" how this happened, he said sarcastically, but the system is currently empty. It was definitely holding 134 as it took several min to empty thru Schrader valve. So, at this time, I cannot do a pressure test, as I haven't ordered the gauges yet either.
I am almost wanting to find out if the compressor is any good, thinking maybe the accumulator is clogged or filter. I mean was blowing cool one moment, then compressor was just off, but didn't lock up like the previous one did.
I want it fixed as I was desperate for a/c, hence just can filling it. But the compressor swap occurred fall last year. The heat and desperation just wanted to see if it would work just a couple weeks ago. I just hope I haven't broken anything. But I almost have plans on compressor, accumulator, o-rings, filter kit from RockAuto, but want to see if compressor can be salvaged. I want it right this time and I didn't know you had to vacuum air/moisture and other stuff out if it opened. I am very good shade tree, but never really dug into auto A/Cs. I have several videos watched, which brought me here! So, thank you :) I am on my way to being more educated properly in A/C work. I value the time you guys have spent helping others.

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Thursday, June 16th, 2022 AT 3:02 PM

KASEKENNY

MECHANIC
18,907 POSTS

Sounds great and thank you for the kind words. We are here to help so I am sure we will figure this out.

If the system is currently empty, then the only way we will know for sure if we have a restriction is to put more Freon in it and check the pressure when the compressor is running. This will tell us everything we need to know about the system.

However, in your current situation I would pull the system into a vacuum with a pump and double check that it holds a vacuum.

If it does, then you can take the lines apart with the system empty and blow compressed air through the different parts of the system. You should be able to pass air through each part of it.

Clearly when you go through the accumulator it will be less air flow but if it is clogged, you will have little to no air.

I would regulate the air down to about 50 PSI at most.

If you have no restrictions, then you should be good. However, the only way to salvage the compressor is to check the pressure.

So that means you will need to charge the system but if you have to replace the compressor, I would replace the accumulator at the same time. It is just a good idea to replace them at the same time.

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Thursday, June 16th, 2022 AT 5:29 PM

LARRYDLTN

MEMBER
3 POSTS

After I get the gauge set, I will keep you apprised when I shoot more freon back in. That is cheaper trouble shooting expense.
Thanks!

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Friday, June 17th, 2022 AT 4:16 AM

KASEKENNY

MECHANIC
18,907 POSTS

Sounds great. Thanks for letting us know. We will wait to hear back.

Also, a lot of those pumps and gauge sets that you can rent will come with a recovery tank so you can at least save the Freon you put in it rather than wasting it.