Condenser copper refrigerant lines were cut by vandals. They stayed open for several days. Before recharching with r-22, i know the repairmen will have to braze the copper lines and remove all the old oil because it was exposed to the ambient and oil absorbs water from the humidity of the air. Im gonna be watching the repairmen closely and want to know about the right way so i will have an educated opinion and be able to question the procedures. How should they purge the old oil? How to add new oil, as i understand the r-22 refrigerant (freon) does not come with oil mixed in?
How to extract and then add new refrigerant oil to a home hvac system after existing oil was contaminated with humidity
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If the lines are two small it will change the efficiency and work the compressor harder. It is tough to fully clean the old mineral oil out that was used in older units. If the R410 smells acidic this could be an indication that the old oil was still in the system and mineral oil and ester oil don't mix. If there is old oil in the system this can cause early compressor failure. I am guessing what he called a diaphragm is the throttle valve or TXV that regulates the flow into the evaporator this could be damaged and part of the reason your system is not cooling. There are many electronic testers that can detect R410 at very small levels if a leak could be located a bubble solution can pinpoint it and there epoxies that may be able to slow or stop the leak but silver solder is the best way (not on a charged unit though) . The possible acid in the oil has caused damage already and compressors are not reparable. I would run the unit until it fails with a full charge it may last the season and shop around for a new system (get several quotes for the complete replacement). I am sure they did not want to put there name on a system that is damaged and have you upset with them as well as the first company for trying to save a few bucks that cost more in the long run.
I would say this is not a DIY project for at least 3,4,5+ reasons the major ones opening a HVAC/R system requires a license, yes you can find R134 In less than 1 lb cans for cars or a duster or electronic troubleshooting freeze spray if you can find the adapters and it would work if you could install new parts and remove all the compressibles (air) and dehydrate the system (a vacuum pump to pull the system to at least 500um). A new filter dryer on the suction line would pickup any metal from the old compressor. I have seen techs "get away with" 1000um but this is risky because any moisture in the POE oil will become acidic and that eats the varnish off the motor windings in the new compressor and then it shorts out. Bringing me to the point is the oil already acidic? We know it is contaminated because of the leak stop being used (leak stop may work on high temp AC like automotive but will plug the capillary tube on most refers). UV dye and or leak stop will void the warranty on almost every compressor I have purchased. Now another non DIY reason you want to repair the leak, how and where did it start leaking? My bet would be in the evaporator, almost all refers have aluminum evaporators and sealing a contaminated aluminum line that has been punctured is almost impossible, I don't do service calls on fridges but have Tryed to help friends that have tried to solder the aluminum lines to watch the line melt (had to replace the evaporator) another friend had a vending machine he tried to use some special 2 part epoxy and thought it was working until he unplugged the system loaded it up and took it to a break room, that warm day caused the Freon pressure to go (calculated) to 275 or so and blew the plug out and sprayed oil and Freon inside the machine (did I mention it did not cool at that point). Now for the last point, did you know there are fines up to $25,000.00 for doing this kind of work without a license?
Best Answer
First you will need a new filter dryer. With the copper repaired Pull a high vacuum below 500um on the system for 24 hours or longer this will remove the moisture. At first you may not be able to get below ~3000um because of the moisture outgassing increases the pressure. Once a good base is achieved keep it there for 24 hours and the moisture will be gone you will also want to do an acid test, if positive you will need to flush the system, I like Qwikshot acid flush. I would probably upgrade to a newer refrigerant that might not cost much more than a recharge since R22 can run 100$ per pound a 5 ton unit the Freon alone could cost you over 1k and you still have an old system.