"Yes, I could google it, but I rather get advise from my Iboats fellow members... "
Whether you take it or not?....
I agree with Bass Tracker...."Danger Will Robinson...danger!".
But since you seem bent on having at it, I won't add any comments on the wisdom or potential safety issues of doing it yourself (unless I have misread, this will be your first A/C adventure)
There are some very real practical issues....
(I will say that in a previous career slot I repaired and rebuilt fairly large refrigeration eqpt ...ice maker and blast freezer compressors....4 and 6 cylinder recip. .....powered by 30, 60 and 75 HP electric motors. This in far-flung locations where you would often have to do a Rube goldberg WRT tools and/or parts. With the big stuff you did have a margin for error.
I would, even today, happily get up to my elbows in a large building a/c chiller or similar.
Auto a/c....not a chance. IMO, it is less "finicky" to work on big systems like that than on an auto A/C system and the chances of a glitch because of the smaller size is greater.I completely understand the systems and components, but without top-end tools and some hands-on experience with auto a/c, my chances would not be great. They have near zero tolerance.)
Trying to extrapolate what I do know to auto a/c and offer some positive suggestions....if there are any auto a/c gurus in here, they may be able to raise a flag if I am being overly-cautious....but it all makes sense to me....
Your two biggest challenges will be internal cleanliness of the system, and complete evacuation before charging.
The smallest speck of dirt or moisture will %$#@^^& it up!
If your old compressor had any parts break up, there may be residue that will plug the tiny orifices in the expansion valve.
Moisture particles will become ice, and do the same.
Google any info you can find on flushing auto a/c systems, and best practices for pumping down.
Also, there are some obvious risks with using a salvage yard compressor....see what you can find out about internal cleaning of the compressor and getting rid of any oil and the contaminants in the oil.
As an example, when I finished an ice maker compressor, I precharged the system with Nitrogen and then pumped down to 29"-30" of vacuum.
Then did it 3 more times. Pump down would take 3 hours+ each time.
Don't try to rush it
You can't afford shortcuts.
You'd get away with a bit of air in with the refrigerant, but not moisture or dirt!
I was using a high performance refrigeration vacuum pump. It would pull below 29" of vacuum. Less than 29" and you will never get the moisture evacuated....and that may be the limitation of the Harbour Freight unit.
After a rebuild on big compressors, you would expect to change the filter and the system dryer a few times in the first weeks , and there were bypass valves that would allow that without having to open the system....in fact on many, you could actually do it with the system running!
Auto A/C doesn't give you that option....but if you are saving a fair bit of $$, and the refrigerant is fairly cheap, it might be a similar result to run for a few hours and then change the filter/drier......pump down and recharge....then do it once more.
For the big systems you can get dryer/filters specially for a rebuild situation, and there might be the equivalent in the Auto world....or maybe not???...
Be careful! and when charging, err on the undercharge side.
Good luck.
