The much lauded AC overhaul is finished!

New compressor, accumulator, orifice tube, o-rings, oil & serentine belt. Wasn't that much of a job actually. It was fun!

Now the tech question... Since the the evaporator and condensor and lines were open to the atmosphere for a few hours, the compressor just minutes, the accumulator just seconds. How long will it take to completely evac the system...rule of thumb? I have a 1/3 HP, 2 CFM vacuum pump running now.

 

This is going to be one of those 'opinion' things.

I vacumn for 24 hours after major component replacement.
You CAN'T vacumn it too long.

BTW: After you pull it down, let it sit for several hours (4,5,6 or 7) and make sure there are no leaks.

Likely it won't be perfect but you can tell this way if you have any leaks that need attention.

After letting it sit, vacumn it some more and then suck the refrigerant in via the vacumn.
Oh, be SURE and put the proper amount (and type) of oil back in there.

Did you have a compressor failure that prompted this job?

If so, did you flush out the condensor,evaporator and all the lines?

 

I don't know if I'll evac it for 24 hours...kinda doubt that but thanks for the reply. This is my first AC overhaul and I'm looking for real world experience. Letting it sit for a time is sound advice. I'll do that even though the manual says if it holds vacuum for at least 5 minutes it's time to charge.

The warranty requirement for the compressor was for PAG oil. So I did flush...sorta. I used brake cleaner and compressed air to clear the condensor and evaporator. Then I added 3 oz of oil to the compressor and turned it over by hand countless revolutions. Just before I installed the accumulator I added 3 oz of oil to it. Broke the seal, added the oil and closed the system. The accumulator wasn't exposed to the atmosphere more than a minute tops. Then I fired up the vacuum pump a minute later.

I thought the compressor was going, turns out the clutch suffered catastrophic failure. There was very little in the way of debris caught by the orifice tube. And there didn't seem to be a great deal gleaned from the flush. It was dirty to be sure but no shavings or metal that I could tell. I broke the clutch loose on the vise and the compressor seemed fine. I started to doubt myself then but the car is old, the compressor was the factory item and so was the accumulator; about 13 years over due for replacement! I'm hoping all will be well with the switch and I'll have honest to goodness ac! :seeya

Thanks again for the reply :thumbs:

 

The key is that you evacuate it until it no longer drops. Usually, after 20 minutes, if you stop, it's going to drop as any additional moisture burns off (unscrupulous shops like to tell you that this is a leak and then charge you for a bunch of unnecessary work). Pag in an R12 system is risky as it just doesn't mix with mineral oil. I think the salesman thought you meant mineral oil or the R12 stuff and really didn't know - maybe the Reman doesnt' know either? You've replaced the components that contain most of the oil and as long as there's no junk in anything else, you're probably ok. Warming up the engine first helps and then vacuum until it holds (I like to let it sit for 24 hours and then vacuum again for about an hour before charging it).

 

what were the finals cost ? compressor? etc? where did u purchase? :) :)

 

SunCr, The salesperson seemed knowledgable. However the BIG flourecent tag wired to the compressor listed specific oil for specific refridgerants and applications under penalty of forfeiture of warranty. GM retrofit conversion said to use pag. I am keeping all of my receipts in case this thing goes south directly.

Vette50, I'm looking at right about $200.00 for the overhaul. I went against better judgement and bought a discount compressor and clutch (as a unit). It was less expensive at $99.99 than buying them seperately. The Accumulator was $58.99, orifice tube was $1.99, o-ring kit was $2.28, 8 oz bottle of oil was $5.99, and the serpentine belt was 34.99. And a couple of cans of refridgerant, still had a couple of cans on the shelf. All in all the replacement was smooth.

 

Proper evaciation would be with a digital guage reading 500-800 microns. If you have a guage set about 29.5" of vaccume since you will never reach a perfect 30". Another good practive would be to pull a vaccume for about 20min, break the vaccume with the vapor of the refrigerant you are using and bring it to about 5psig, then pull a vaccume again. Do this 3x's and you should be clear of non-condensibles. You should have a good vaccume after about 20-30min with a clean system and good vaccume pump.

I only have to run a pump for 24 hours on huge built up a/c systems that the piping was done in wet conditions, and held around 500 pounds or more of refigerant. Not on a system in a car that only holds 2 pounds or so. :cheers:

 

I always warm up the engine, by taking a drive, before I evac.. The underhood temp. will help boil off any moisture while evacing the system.

 

OH YEAH! Gotta love a cold ac! And something must be working right...we went for a lil drive and got her temp up to 202. I turned into the local Sonic drive-in to get a cherry-limeade and switched on the aux fan. While sitting in the drive thru the temp was actually dropping...never done that before...down to 194 at a complete stop. It was warm and very humid today, I don't have the numbers, but the ac vent temp never exceeded 60* in traffic and stopped, and the coolest was 47* on the hiway at 65mph. I'd prefer it froze me outta the car but I'm liking this so far! And SOOOOOOO quiet!