ac comp. oil

[454ss]

i am going to replace the ac compressor on my 1997 gmc and need to know how much pag oil to add and where to add it. thanks for your help.

[snoman]

i am going to replace the ac compressor on my 1997 gmc and need to know how much pag oil to add and where to add it. thanks for your help.

 

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Your compressor should come precharge with oil and if not it should be clealy labeld as to how much PAG to ad to it. (They are pretty good about this and last few I did where labled as such.) If there is not label or you want to be more exact, remove old compressor and drain oil from it and add the same amount of new oil to new compressor before installing it. (this is what I usually do) .

[454ss]

the one i bought came dry and it doesnt indicate where or how much to add, it just says to add pag oil at installation. the old one probably is empty or has very little in it from leaking out at a bad line.

[ChevyTech007]

Usually 2 oz is about right.

[snoman]

the one i bought came dry and it doesnt indicate where or how much to add, it just says to add pag oil at installation. the old one probably is empty or has very little in it from leaking out at a bad line.

 

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Unless you can see a oil track from a leak, do not assume it is gone as it flows through system with refigerant. I replace what comes out of compressor unless I am starting with a new system as a oil overcharge is not good. 2 oz may not break the bank but it does not help it if it is not needed.

[454ss]

thanks guys, i will see if anything is in there.

[snoman]

thanks guys, i will see if anything is in there.

 

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Make sure you replace recver/dryer too (never change a compressor with doing this) and I would replace expansion valve too while it is open as the screen in it can become plugged with age. The dryer should state how much oil to add (about 1.5 oz as I recall)

[454ss]

what is the expansion valve and where is it located? thanks this is my first time working on a ac system.

[pm26]

what is the expansion valve and where is it located? thanks this is my first time working on a ac system.

 

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If you have never worked on an A/C system, suggest you let a properly equipped shop handle this. Believe me, it is not worth it if you do not know what you are doing and do not have the proper equipment. You need to pull vacuum on the system prior to recharging it. You need to use special sealing A/C O rings and need to tighten them just right to seal properly. You need to use the right amount of correct refrigerant oil. A/C shops have machines that automatically mix the oil with refrigerant for proper ratio.

 

I know a guy who ruined a brand new compressor in less than a year because he overcharged the system.

[454ss]

the system is already empty and im not going to charge it myself, im just replacing the parts because i dont need to pay somebody else to do it.

[snoman]

the system is already empty and im not going to charge it myself, im just replacing the parts because i dont need to pay somebody else to do it.

 

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I agree with you fully. The expansion valve is located inside the fitting where the high pressure line from condensor attachs to the input to the evaporator. I can provide a picture of it if need be but you should be able to find it. (go to a auto parts store and buy/look at the expansion valve for it and you will see how it can fit inside a joint/coupler)

[snoman]

I know a guy who ruined a brand new compressor in less than a year because he overcharged the system.

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And I have seen some "professionals" that are supposed to know betterscrew them up too. It is not rocket science to work on one.

[ChevyTech007]

You have an orifice, not an expansion valve. It is in the same location but it is a different setup. Take the smaller line at the evaporator apart and you can reach in the evaporator inlet with needle nosed pilers and pull the orifice out. They can stick so be careful not to break it off. You will need to have it charged by a shop. A vacuum will have to be pulled on the system.

[snoman]

You have an orifice, not an expansion valve.

 

Actually you can call it a expandtion valve too as the liquid is expanded to gas as it passes through it into a lower pressure area. It is fixed in nature now on most vehicles but they were tempature controlled and varible 30 years a go and more. (there is a after market internal variable valve that will retrofit too) Orfice can "work" as a name too but expandtion valve is more correct here because you can have a orifice to restrict flow without expanding anything and the liquid is expanding to gas as it pass through it. Heck I guess someone could even call it a "conversion" valve if they wanted too but I have never heard it called that.