You mean 134A?    First, there is specific flush to use to clean the insides of ac lines.   You need a flush gun to use it for best results.

Second, do you remember if your compressor came pre loaded with oil?  As far as the lines, it would probably be best to flush the components in pieces and replace all the o rings at the same time.   You will also need a brand new reciever/dryer, as oil pools in them and you will never get it clean.  They are cheap.   If the compressor has never been opened, it is most likely good to go.

Third,  a good vacuum is needed to be drawn on the system before you add the 134A.

Do you have any of the paperwork that came with that compressor?    I have all the tools to accomplish your task.   A set of manifold gauges, a vacuum pump, and a flush gun.   

Last edited by Greg B (5/20/2014 4:06 PM)

Yes, R-12 is Freon, isn't it?  Yes I mean 134A.  Converting to 134A.  Thanks.  I do have a new dryer.  Compressor has never been opened.  The compressor was sold as having the oil already in it.  I never figured out if it meant it had enough for the entire system.  I'm sure I do have paperwork, but I will have to do some looking for it.  I have a good vacuum pump.  It was being used in a dental lab.  It doesn't necessarily have the correct fittings.  Wow, if you're offering to help, I had better take you up on it.  It would be rude not to!  So I will get myself partially back together and beg you for some of your supervision and expertise!  Thanks Greg.  I have two families moving to new homes this weekend, so I'll be busy Friday and Saturday, and probably not be able to walk Sunday.  I have no idea what you're schedule looks like.  You'll have to shoot me an email, or I can send one your way.  You're a good man!

Lance

Last edited by Lance (5/22/2014 9:26 AM)

As someone suggested use actual A/C flush for your components. Hopefully I can lay this out good, as I have not been working as a tech for 8 years.
R12 systems (original system) used mineral oil. Current 134A systems use PAG oil (Ford Chevy and Mopar have their own respective weight) . Retrofit systems use Ester oil. This has been the rule of thumb 8 years ago and may have changed since. Since you are flushing the system you may be able to use the right PAG oil, that can be purchased at an automotive store or an ester oil. Assuming the system is currently empty (no refrigerent charge) it would be a good idea to flush what ever you are re using with actual AC flush.

This next part will depend on if you have retrofit hoses or are using originals. Original hoses (R12) will have screw on type fittings, R134 hoses have larger fittings that are like a quick coupler snap on. Retrofit hoses will have the correct fittings on them also the R134A couplers are available to screw on the old R12 fittings. I would definately recommend the correct fittings as this will make things easier down the road and also alert anyone working on the AC that it has been retrofitted with R134A. A quick description of the hoses (blue)= the low side or cold side. Called low side because it is the low pressure side of the system. (red)= high side or hot side, because you guessed it , it is high pressure. Low side lines are larger in diameter and high side lines are smaller in diameter.
As far as determining how much oil goes into the system, there should be a system spec for when it used R12. probably around 8-12 ounces of oil and roughly 2- 2.5 lbs of refrigerant. You dont want to put all the oil in one part of the system either. Couple of ounces in the condenser, couple ounces in the lines etc. Might be a good idea to drain the oil out of the compressor just by tipping it and replacing it with fresh oil as well. Make sure the compressor turns by hand after doing so, by grabbing the clutch on the front of it.

Alright if you are still following along and not sleeping, and have your AC system completely assembled. I personally recommend this part for a shop that does AC work, or if you know someone that has AC equipment by all means here we go. Connect gauges to your system and get your system under a vacuum. Usually around 20- 25Hg of vacuum. Run vacuum pump for 30 minutes on system. If you notice your gauge pulling vacuum and then not pulling vacuum you have a leak in your system. If the gauge says the vacuum is good for 30 mins close the valve from the vacuum pump to isolate the system. If the gauge does not move for 15 minutes your system is leak free. Pulling your system into a vacuum does 3 things. 1 under a vacuum for 30 mins removes all the moisture from your system by having it open while cleaning etc. 2 It tests for leaks before you add expensive freon. 3 It will actually aid in adding freon to your system by using the vacuum to suck it in the system.

Part 72 Still here? If your system checks out good by holding a vacuum, next is adding refrigerant. You do not want any air or moisture in your AC system. Now this is where this can be done a number of different ways, and I am assuming you will have someone help you that knows this already. Using a manual gauge set and a hopefully large can of R134(30lb). you will need a scale, digital for accuracy. By scale I mean one that you weigh yourself on. Why do you need a scale? So you know how much refrigerant is going in your system. There is a spec for every car. Auto manufacturers recommend filling on the high side, but this may take longer than you would like. With your gauge set on whatever side of your system you want (high or low), connect your refrigerant source to the gauge set (yellow hose- same one the vacuum pump was on). Put your refrigerant source on your scale. open the gauges that your refrigerant is on. Remember that system vacuum that was still going on. Here is where it helps us. By opening the valve on the gauge that is connected to your AC system , the vacuum that your system is under will aid refrigerant into your AC system until the pressure equalizes. Keep an eye on your scale. Start your car up and turn your AC on. Your AC clutch will probably cycle rapidly for a while until your system draws in more refrigerant. Once the AC system pulls in the remaining amount of required refrigerant, close your gauge valves.

Being a retrofit system, it may require more R134 refrigerant than the old R12 system did. This is where the troubleshooting part begins. I'll save it for another post if you make it this far without taking a bottle of aspirin.

Last edited by MachTJ (5/20/2014 6:47 PM)

Have messed with auto AC for many years and prefer to use a sight glass to determine when unit is full of Freon. Especially since I don't own a good scale!
MachTJ, is sight glass a valid method?
Howard

Last edited by hmartin025 (5/20/2014 11:22 PM)

I have  sight glass built into the line running along the driver's shock tower.  The lines I bought were made to fit current configuration, and I intend to charge it with whatever it was built to handle.  Last time I had it running was with R12 with old Tecumseh compresser and original-ish lines.  This entire system is essentially new, but has been sitting un connected, unused for 7 years or so.  Thank you all for the help.  I'll dig for the correct paperwork and info.

I wasn't kidding about my ignorance, was I? :-)

Lance

How are you making fittings, Greg? Got a crimper?

Have I told you that you are my new best friend???