08navigator
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This sounds like it should work. If I put 1.5oz of pag oil in the line I'm replacing, will the vacuum pump pull it out or not bother it?
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Rear a/c leak
- Thread starter 08navigator
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Vacuum pump won't remove it if you put on line as that's a long way from the ports you are vacuuming from. If you shoot it in with a small pressurized can of pag46 you will do it after the pump down.
You can even do repair, hook pump up to high (small line) side then use charging hose or gauge hose to hook to low side one stick other end into oil. Using red side gauge handle valve to control suction.
Then after oil is in hook hose end to manifold gauge and open red high side valve again full open for 4-5 mins before opening blue low side.
When pumping down always open valves all the way.
I reach down and manually turn comp over by hand 10-15 times to displace any air in the up to six pistons they have.
You can even do repair, hook pump up to high (small line) side then use charging hose or gauge hose to hook to low side one stick other end into oil. Using red side gauge handle valve to control suction.
Then after oil is in hook hose end to manifold gauge and open red high side valve again full open for 4-5 mins before opening blue low side.
When pumping down always open valves all the way.
I reach down and manually turn comp over by hand 10-15 times to displace any air in the up to six pistons they have.
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Motorcity muscle
Full Access Members
Lot of bad info in this thread, liquid refrigerant and oil will damage skin/eyes. Be safe, wear gloves and goggles. Best way to check for leak after repairs is with nitrogen. If air/moisture is left in a closed refrigeration system it will create acid and damage compressor. Could make repairs and have system charged at shop.
gixer2000
Retrofit or Bust
How many people doing this work at home have access to nitrogen or a regulator? Sure, anyone can go buy one but not everyone has the funds to do so.
As for leak testing the best way is actually in a vacuum with a micron gauge. A vacuum decay test would laugh at a pressure test and can be done much faster than a pressure test. A legit pressure test should sit for 24hr while a decay test with a micron gauge takes an hour once its below 500 microns.
I find more leaks in commercial and industrial equipment with a decay test over a pressure test but again, not equipment the home mechanic owns.
As for acid being formed from air and moisture being left behind. Automotive AC compressors aren't affected by acid like a traditional compressor that runs on AC or DC voltage is. The acid actually breaks down the coating around the motor windings causing a short within the windings. Automotive compressors don't have have windings and the acid doesn't eat steel, brass, copper or aluminum so....
I am in no way saying its ok to purge refrigerant before charging or to skip a vacuum but when the equipment isn't available you do what needs to be done because in an automotive application, it will work!
Always wear PPE! Glasses and gloves are important
I've never drawn a vacuum on any of the a/c systems I've cracked open. Just re-charged. Never had a problem.
gixer2000
Retrofit or Bust
That's basically what I was explaining to the person I quoted. Sure, its not the right way but you work with what you have. Even though I don't agree with the method it does work
Exactly why I specified in my post that it's a very variable procedure in working on AC Automotive Systems. What was the right way 20 years ago is no longer considered the right way. For some people the right way is whatever way gets the job done and works.
Very few people worry about R12 or R134a getting on your skin they worry more about frostbite from it blowing off. Of course it's not a good idea to get it on you repeatedly but doing one repair one time on a vehicle is completely different than a tech doing it all summer long. You basically just wipe it off your hands with a towel. Yes, the frost could damage your eyes to but once again very few techs wear safety glasses from working AC systems. If a line were to happen to blow off and vent refrigerant you just turn your head real fast. That's how most of the world techs do it.
Hardly anyone or any shops use nitrogen for automotive pressure testing. That is a commercial and residential procedure. Automotive pumps them down and uses a micron gauge as stated by a previous poster.
I don't think I've seen any bad information in this thread.
You can leave an AC compressor sitting on a shelf for years and still put it on a system pump it down it will work just fine. The only thing that is sensitive to moisture are the receiver dryers and dryers in the accumulator / AV bottle. It is of course better to only leave a system open for his little time that you have to.
Very few people worry about R12 or R134a getting on your skin they worry more about frostbite from it blowing off. Of course it's not a good idea to get it on you repeatedly but doing one repair one time on a vehicle is completely different than a tech doing it all summer long. You basically just wipe it off your hands with a towel. Yes, the frost could damage your eyes to but once again very few techs wear safety glasses from working AC systems. If a line were to happen to blow off and vent refrigerant you just turn your head real fast. That's how most of the world techs do it.
Hardly anyone or any shops use nitrogen for automotive pressure testing. That is a commercial and residential procedure. Automotive pumps them down and uses a micron gauge as stated by a previous poster.
I don't think I've seen any bad information in this thread.
You can leave an AC compressor sitting on a shelf for years and still put it on a system pump it down it will work just fine. The only thing that is sensitive to moisture are the receiver dryers and dryers in the accumulator / AV bottle. It is of course better to only leave a system open for his little time that you have to.
08navigator
Full Access Members
I already purchased the vacuum pump. I will Purge the air out of the charge line prior to charging. If I pull a vacuum on the system the water should boil off. I do not have access to nitrogen and the only way I'll be checking for leaks is with dye after charging it. I'm buying the equipment to charge it myself for a few reasons. 1. If it leaks I can try again and it will only cost me some more 134a. 2. I can use it on my other vehicles. 3. I don't have a three. Just because I guess.
Thanks for the info everybody. I love hearing from as many as possible since everybody does it differently. I know I could probably get by just charging the system but for the minimal investment I would rather vacuum the system down and do it right.
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Thanks for the info everybody. I love hearing from as many as possible since everybody does it differently. I know I could probably get by just charging the system but for the minimal investment I would rather vacuum the system down and do it right.
Sent from my Pixel XL using Tapatalk
gixer2000
Retrofit or Bust
The vacuum will boil off any moisture left behind but I would let the vacuum run for a while. You really can't put a time on a vacuum but give it as much time as you can since you really have no way to measure it accurately
I always like to pump them down for at least 25 to 35 minutes if they've been open for any length of time. Ideally 45 is even better. If they have only been open for a few minutes while I am doing a repair like replacing an orifice tube or something like that then I'm simply pumping them down for less than 10 minutes just to get rid of the outside atmospheric pressure.
I repair the AC systems for decades replacing compressors and charging without fully understanding the way the system really works. Things like the high-side and low-side, liquid line suction line. Without really understanding that the all the high pressure lines are not liquid and understanding the phase change and the direction and path that the refrigerant takes through the system and when and where things occur.
None of that really matters when you just need a leak fixed or a new compressor installed but it does help in diagnosing weird gauge readings on systems.
I repair the AC systems for decades replacing compressors and charging without fully understanding the way the system really works. Things like the high-side and low-side, liquid line suction line. Without really understanding that the all the high pressure lines are not liquid and understanding the phase change and the direction and path that the refrigerant takes through the system and when and where things occur.
None of that really matters when you just need a leak fixed or a new compressor installed but it does help in diagnosing weird gauge readings on systems.
