A-6 compressor removal common mistake!x

[Domenic T.]

I have had questions about poor cooling and other problems dealing with the AC system after removal of the compressor for repair or replacement.
It is important to measure the amount of oil removed from the compressor if you are not going to flush the complete system and replace all the oil.
The amount of oil removed will give you a clue as to how much is in the system and if your oil was overfilled causing poor cooling AND excessive engine temp while using your AC.
To much oil or refrigerant will cause the condenser to over heat and pass the hot air thru the engine radiator.
The A-6 compressor has a oil pan, oil pick up tube, and oil pump inside, and it's oil level. It is as important as any other oil level in your car as it lubes 4 internal bearings, front seal, and assists in the ring lubrication.
Some compressors (newer design) do not have this system with a oil pan and lube like a 2 stroke engine.
1- you need to know what you removed to see if it was correct, (4 to 6oz.) this will let you or your mechanic know if you need oil attention down stream.
2- If it was overfilled when removed and you are re-installing after repair, and your system seemed OK
before removal, you can now install it with the correct amount.
3- it is possible to remove excess oil while system is charged by cracking the drain plug and letting the excess oil stream out until the refrigerant gas appears.
Bottom line is that it is important to measure the oil and that oil is at right level/amount in compressor at installation.
Some shops that are not familiar with the A-6 have not added oil to the compressors prior to installation and relied on adding a oil charge during the gas charge which will starve the bearings and front seal and cause early failure.
All is in the MANUAL and it will say it much better than I. My point was to make sure the manual is there and the newer mechanics are made aware. Made aware can upset some but you can always hand them a complimentary print out of the pages so they don't need to find the info.

DOM
3- if you did not

[Leif A.]

Re: A-6 compressor removal common mistake!x

Dom,

Is there a way to "check" the oil level in a compressor like we can on our engine block? I know there isn't a dipstick but is there some other way without removing the compressor? Your article has me wondering if my compressor has the correct amount of oil and if not could be contributing to my warmer than I like engine temp.

Thanks for the heads-up.

Leif

[Domenic T.]

Re: A-6 compressor removal common mistake!x

Leif,
yes there is a way but I ever did it. With, the engine off, the dain plug is at the correct level. With system pressure you can open the plug till the oil seeps out. when the gas hisses your done. If a bunch comes out then do it again after a few hours use on the road.

DOM

[Leif A.]

Re: A-6 compressor removal common mistake!x

Leif,
yes there is a way but I ever did it. With, the engine off, the dain plug is at the correct level. With system pressure you can open the plug till the oil seeps out. when the gas hisses your done. If a bunch comes out then do it again after a few hours use on the road.

DOM

Thanx very much, Dom.

[Domenic T.]

Re: A-6 compressor removal common mistake!x

Leif,
I was watching my son charge a 91 suburban at 2K RPM's and saw the pressure change when the fan clutch cycled.
The pressure rose from 300PSI to 350PSI in the system when the fan clutch kicked out. That pressure increase in the condenser at 350 would raise the temp of the air that had to go thru the radiator.
Made me think, it's like raising the ambient temp outside that had to pass thru the radiator.
I watched another system that had a separate electric fan that was just for that problem. Kinda hard to keep these older cars cool that have AC!
Just wanted to share about the pressure rise causing more heat! What a heat cycle!
DOM

[Gary N.]

Re: A-6 compressor removal common mistake!x

Dom,
If you crack the drain plug and it hisses gas immediately with no oil seeping out this will only tell you it is not over full, but it doesn't tell you if you need to add any oil (needs oil). I suppose you could add some oil a little bit at a time using the small cans of R-12 and oil and repeat this until you started to see some oil seep out using your oil check method. How about when you change out a dryer? I doubt that any oil can be drained out of it.
Gary

[Domenic T.]

Re: A-6 compressor removal common mistake!x

Gary,
I never tried to drain a dryer but did remove the oil and change the desecant in them. I think the safe way is to add the few oz. that the manual says it holds. In a fresh system the manual says 6oz. In the compressor, 2oz in the dryer, and 3oz. In the evaporator, a total of 11oz.
My son does installations on a regular bassis and says he flushes each out and starts fresh. As I remember your compressor had about 6 1/2 oz. In it, so if you changed the drier without adding oil you would be at the low level in the compressor.
It would be nice if one of the installation experts that understands the older system would chime in and explain how the oil settles in each area. I know oil travels with the gas and lubes the upper end of the compressor and makes it to the oil pan along with lubing everything else. I think you would be OK adding a few oz. Of oil because it seems that you are not overcharged with oil from what you say.
I think that the drain plug was not put on the bottom of the pan and was for the purpose of checking for the over fill.
I will do some checking and get back.

Dom

[Gary N.]

Re: A-6 compressor removal common mistake!x

Dom,My AC system is working great and has been doing so for about four or five years now. It blows very cold and I am very satisfied with it. I did add a 2 oz. can of R-12/oil mix when I changed out the dryer, so I believe I am OK oil wise. Your rebuilding of the compressor was well worth it. I don't believe were very good at not running hotter with the AC on though. I'm good as long as I'm moving, but it doesn't take to long when I'm stopped or in slow traffic to see the temp gauge start to raise. I have a new radiator, but I think that having the condenser in front of it and giving off heat with the AC on is not very efficient, especially with a slanted radiator position.Thanks again,Gary

[Domenic T.]

Re: A-6 compressor removal common mistake!x

Gary,
I think your system is probably working the way it is supposed to. I did some research and found myself confused. the procedure of cracking the drain plug is if there is a probable oil overcharge. book says nothing about adding oil to the dryer, condenser, or evaporator when only changing any one of them. It does say what each should hold, and this book has the 11oz. total but comp=6, condenser=1, dryer=1, and evaporator=3. It does talk about only adding what you measured when you removed the compressor.
I read it to say if less than 1 1/2oz. is measured then add 6oz. to system. My son flushes the system with air condition flushing solvent followed by blowing the oil & solvent out with clean air. One component at a time. takes a few solvent washes to get the oil out. There was another post that said their temp tests it. did the same as you are describing. Glad to hear all is well with your vette.

DOM

Leif,
The cracking of the plug and draining was on the suspected over fill and some other info above, keeping cool with these beautiful monsters is not that easy.

DOM

[Leif A.]

Re: A-6 compressor removal common mistake!x

Dom and Gary,

Thanks for the great "back and forth" info. Constantly gathering info on these cars and storing it away for future/current reference.

Regards,
Leif

[Domenic T.]

Re: A-6 compressor removal common mistake!x

Dave,
Your post made it to my Email but I can't find it here.

It was true that when the fan clutch kicked out, the pressure rose from 300 to 350, I have no reason to lie about that as I was sharing something I learned.
1- What I do know is that when the ambient temp is 115 you will get a higher pressure such as the 300PSI.
that was the case.
2- The car was static and not getting any airflow thru the condenser which caused the condenser to get hot and cause a temp change that rose the ambient at the condenser as the air flow was decreased which brought the PSI IMMEDIATELY to 350.
3- The rise in pressure caused a rise in heat as it does when air compressor air go's thru it's cooler, the higher the air pressure the hotter the cooler gets. In this case the lack of air thru the condenser caused a rise in ambient which will cause the pressure to rise.
That's what I saw and it was not R-12. Yes 350 is scary but that's what happened on the dial. This was on a 91 Suburban with dual air using R-134.
I am sure you have more knowledge than I as I do not do this on a regular basis (installation) but the charts on charge pressures all differ as the ambient rises and it's nothing to see 120 here.
All I am doing is passing information on that caused me to learn more about what causes the cooling systems loose their ability to cool when the cars are in stop & go.
Again, I am not in disagreement with you just telling it as I saw & perceived it as it was being explained to me.

DOM