Ok so here it is.
I am going to be replacing the ac compressor condenser orifice and new gaskets and such, so my system is empty of r134a due to a failed compressor. My question is do I need to have it evac before installing new parts or do I just install, oiling where necessary and then take it to be charged?
Thanks!

 

Is the system clean? Is there metal in the system due to compressor failure?
If not you will have to install compressor look up how much oil you need to add to compressor as a rule at least 2m ozs.Ester oil is the best. Then install remainder of parts. Pull a vacuum on system then charge

 

I'm don't believe there is any metal shavings in the system.I think that it was just one of the seals in the compressor but I'm not sure at this point. I have the parts coming and just want to know should it be evacuated before or after the swap? Since the leak let out the freon.or would it be ok to replace parts and have the ac shop evacuate and refill the pag and recharge or if it would be ok to just put the pag in and drive it to the shop and have them charge it.
Thanks!

 

i would flush out all the old parts u r still going to use just to make sure its all clean an u have to add a little oil to all ur new parts but dont go over what the system calls for

 

If the orifice strainer has any contaminants or metal shavings in it or the old oil is not clean you should flush out all the lines and coils. You need dry nitrogen to blow the flush through lines and coils and to pressure check for leaks. Compressed air has moisture it and should not be used.

Install your new parts, then install a new accumulator drier. Next check for leaks.

Before charging you must evacuate to remove air and moisture. Air left in the system will cause hi pressure on the condenser side and moisture will react over time with the system oil and refrigerant and cause acids and sludge to form inside of the system.

The Poe oils used with R-134a will suck water out of the air and hold it. Even if you evacuate it will not easily come out of the oil.

You do not want you system open any longer than needed.

When I work on a refrigeration or air conditioner with Poe oil they tell us not to have the oil exposed to the atmosphere any more than 15 mins.

I flow dry nitrogen at low pressure and keep lines plugged when I have to open a system.
If you still have a little moister left after the evacuation the new accumulator drier will trap it.

Most people do not have access to things like dry nitrogen and vacuum pumps.

Blazeme

 

So as long as I swap the parts quickly and then have the system flushed and charged at a shop will it be ok?

 

If your system has no pressure in it now it may already have allot of moisture in it. If so it should be flushed.

The flush needs done then the new accumulator drier installed, next the vacuum.

The oil in the new compressor should not be exposed to moisture in the atmosphere or in the system for more than 15 minutes. Also the new accumulator drier should be put on immediately before the vacuum is pulled.

If there is at least a little pressure left now you are allot less likely to have moisture in the system. If the system is dry, the oil is clean and the strainer is clean you may not need to flush anything.

If you can gain access to a vacuum pump you could change the parts quickly and immediately pull a vacuum. You should then be ok to recharge it.

Hopes this helps
Blazeme