R134a Oil Question

[e3mt]

Car is a 1994 Legacy L with R134a.

Am replacing my ac compressor, but am unsure about the oil type I need. Local auto place has a low viscosity oil and a high viscosity oil. Does it matter which I use?

Also I do not know the exact amount to use. Would it be best to just empty my old compressor and put the same amount back in?

Thanks - Mark

[idosubaru]

if you want to be very technial on the issue look it up on the internet, tons of R134a and r12 charging information all over the place, very easy to find.

 

draining and filling with the same amount will work just fine. get some in the compressor and turn the pulley plenty of times by hand just to work everything around internally.

 

i slapped a compressor on a friends honda over a year ago without adding any oil to it....i didn't recommend doing it that way but he was impatient and insisted on not adding any oil and wouldn't let me pull a vacuum. i don't recommend skipping either of those steps, but his a/c is still blowing arctic air.

 

if the R134a you're recharging with already has oil in it then this really becomes a dead horse.

 

i'd be more concerned about installing new schrader valves on your high and low sides than anything else. they cost like 50 cents and are easy to replace (don't require a special tool) with the system open. they have a small o-ring at the base that is the cause of most a/c problems i've encountered.....although bad compressors are probably equal on that list. i've yet to hear of someone i know only spending 50 dollars on having their a/c fixed..it's always in the hundreds....but i know for a fact that some of those repairs had to be only 50 cent schrader valve failures. i wonder how many 50 cent schrader valves are replaced for hundreds of dollars? with the right tool you can even keep the system closed while replacing and not loose any refrigerant, so no need to pull a vacuum typically.

[Legacy777]

You need PAG 100 oil. I believe the total system oil amount is like 5.8 oz or something like that. I can check, I've got a book at home.

 

Dumping out the old oil, measuring it, and putting the same amount back in is fine too.

 

You should replace the receiver drier as well since the system is open.

 

Just curious, why are you replacing the compressor? Did it die?

[e3mt]

Yup, Compressor died. I appreciate the info.

 

mark

 

You need PAG 100 oil. I believe the total system oil amount is like 5.8 oz or something like that. I can check, I've got a book at home.

 

Dumping out the old oil, measuring it, and putting the same amount back in is fine too.

 

You should replace the receiver drier as well since the system is open.

 

Just curious, why are you replacing the compressor? Did it die?

[Legacy777]

You really need to flush the system thoroughly. I had a compressor knocking, replaced it. It worked fine for a while, but did eventually die. I recently yanked the condensor out, and there were small metal flakes at the bottom outlet.

 

I'd really recommend pulling all the components out and flushing them thorughly. They make a flush, however brake cleaner will work just as well.