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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / October 2004Black Death in A/C System Questions
When you remove a seized compressor and the oil looks very black with aluminum bits in it is it called black death? After the compressor was removed, I flushed the whole system with a quart of A/C Flush and Cleaner under compressed air. I fabricated a device to attach my shop-compressed-air to the non-suction side of the hose casting that attaches to the A/C compressor. I would fill an attached plastic tube with some flush liquid and blow it though the system with compressed air. It would exit the suction side of the same alumninum casting that attached to the compresser. I could see it bubbling in the dryer as I did that process repititively until the whole quart of flush oil was used up. After blowing the flush oil through a little bit, it would eventually start to spit out of the exit whole, indicating to me that it was traveling throughout the whole A/C system. The bottle said you are supposed to disconnect everything in the system and blow it through...condenser, evaporator, hoses, dryer, etc. That was not an option for me. It's like "disconnect the evaporator" as if it isn't a big deal...that can take 10 hours even if you know what you are doing. Nearing the end of the bottle of flush the refuse blowing out the exit started to get somewhat clean. The flush was kind of grey/clean looking...but never totally clean/clear yellow like new oil. I wasn't satisfied with that totally, but couldn't afford another bottle of flush at $20 a pop. Anyway, I filled the new compressor with 8 oz. of ester oil, replaced the o-rings and installed it. I charged the system with freon without evacuating it. The I bled half out, and charged it again. Then I bled half out again, and charged it a third time. This is an old trick if you don't have an evacuator and it has worked successfully in cars for years for me. OK, I know not every "technique" here is ASE-certified/endorsed, and it is "unwise" not to replace the dryer, but the fact is these methods have worked for me for a long time. In fact usually for years and years on end. In this case though, it didn't work. So, without criticizing how stupid the techniques are (such as not replacing the dryer immediately), and knowing that the system absolutely has the correct pressure and amount of freon in it, and the compressor IS functioning properly, can you tell me the most likely reason the system in not blowing cold? And, lastly, can you recommend what the next things I should replace are -- how about the dryer and expansion valve? They are probably clogged after an A/C black death, right? And they would prevent it from blowing cold if they were clogged right? Thanks-in-advance! Michelle P.S. My e-mail isn't working right now, so please reply to the newsgroup post. > When you remove a seized compressor and the oil looks very black with > aluminum bits in it is it called black death? Yes. > After the compressor was removed, I flushed the whole system with a > quart of A/C Flush and Cleaner under compressed air. Frequently insufficient. The passages in recent systems' evaporators and condensers, amongst other components, are so small that considerable debris can become permanently lodged despite all flush efforts. > The bottle said you are supposed to disconnect everything in the system > and blow it through...condenser, evaporator, hoses, dryer, etc. Yes...if there's to be any prayer of the flush being effective, this is necessary. > That was not an option for me. It's like "disconnect the evaporator" as > if it isn't a big deal...that can take 10 hours even if you know what > you are doing. Horseshit. This indicates you're not very familiar with automotive A/C systems in general, let alone your specific system. > Not satisfied with that totally, but couldn't afford another bottle of > flush at $20 a pop. Your system WILL fail again if you do half-assed work like this. > Anyway, I filled the new compressor with 8 oz. of ester oil, replaced > the o-rings and installed it. I charged the system with freon without > evacuating it. The I bled half out, and charged it again. Then I > bled half out again, and charged it a third time. This is an old > trick if you don't have an evacuator More half-assed work. > OK, I know not every "technique" here is ASE-certified/endorsed, and > it is "unwise" not to replace the dryer Not "unwise" -- plumb stupid is more like it. > In this case though, it didn't work. Naw sh.t? > So, without criticizing how stupid the techniques are (such as not > replacing the dryer Too late. You do stupid sh.t, and then beg for help when it doesn't work, you can expect to be smacked for doing stupid sh.t. > can you tell me the most likely reason the system in not > blowing cold? Yep: You did stupid sh.t and halfassed work. > P.S. My e-mail isn't working right now Maybe you shouldn't have tried flushing it. > When you remove a seized compressor and the oil looks very black with > aluminum bits in it is it called black death? [quoted text clipped - 51 lines] > P.S. My e-mail isn't working right now, so please reply to the > newsgroup post. It sounds like you have some idea of what should have been done but decided to take the cheap and easy way out. I guess you got what you paid for. I don't mean to be harsh but there is a reason A/C work is expensive. You never did say if you replaced the compressor with a new or used or remanufactured unit, or did you just reinstall the original? Bob > When you remove a seized compressor and the oil looks very black with > aluminum bits in it is it called black death? > > After the compressor was removed, I flushed the whole system with a > quart of A/C Flush and Cleaner under compressed air. You don't need to use this. Plain old Mineral Spirits from the hardware store works fine. And a quart is totally insufficient. When I flushed my A/C 2 years ago I used TWO QUARTS of mineral spirits PER SECTION followed by at least 3 minutes of dry air at 100psi to dry them out. One quart ran one direction then I changed sides and ran the other quart the other direction. The mineral spirits that came out is still in my garage in the gallon cans. I use it for cleaning paint brushes and parts and such from time to time. I figure in another 5 years I will have used it up. I think you can burn the stuff in kerosene lamps and the like, that is if you go camping. You just make sure that you let the debris settle out of it. > I fabricated a > device to attach my shop-compressed-air to the non-suction side of the You can purchase for about $25 an aluminum quart bottle and hose and gun that is specifically designed for this. This allows you to put the full pressure of the air compressor (at least 100psi or more if you can get it) behind the liquid flush medium. In my case I used an old heater hose and a clamp on the exit side of the line to redirect the flushate into a catch basin. > hose casting that attaches to the A/C compressor. I would fill an > attached plastic tube with some flush liquid and blow it though the [quoted text clipped - 3 lines] > it bubbling in the dryer as I did that process repititively until the > whole quart of flush oil was used up. If the A/C system has been compromised with a blown compressor the dryer is shot. > The bottle said you are supposed to disconnect everything in the > system and blow it through...condenser, evaporator, hoses, dryer, etc. > That was not an option for me. It's like "disconnect the evaporator" > as if it isn't a big deal...that can take 10 hours even if you know > what you are doing. Right. However you do not need to REMOVE all of the devices just disconnect them. > Nearing the end of the bottle of flush the refuse blowing out the exit > started to get somewhat clean. The flush was kind of grey/clean [quoted text clipped - 8 lines] > trick if you don't have an evacuator and it has worked successfully in > cars for years for me. Where did you get the freon? Freon, ie: R12, is a controlled substance now and you cannot purchase it without a license. And if you have the license you should know that venting refrigerant to the atmosphere is verbotin. And this trick is pretty dumb anyway. Moisture in the system settles into the rubber walls of the refrigerant lines and is present throughout the system. After a flush you really need to put the system under vacuum for at least 4-6 hours to boil out the water. > OK, I know not every "technique" here is ASE-certified/endorsed, and > it is "unwise" not to replace the dryer, but the fact is these methods > have worked for me for a long time. In fact usually for years and > years on end. Sure, sure. Tell us another story. > In this case though, it didn't work. So, without criticizing how > stupid the techniques are (such as not replacing the dryer > immediately), and knowing that the system absolutely has the correct > pressure and amount of freon in it, and the compressor IS functioning > properly, can you tell me the most likely reason the system in not > blowing cold? For starters, refrigerant amounts and pressures don't have to be absolutely correct. If the system is completely clean, which yours isn't, then an ounce or 2 of freon off the mark isn't going to make any difference. And systems will run for years with low oil. You get things as close as you can with a scale, and with measuring out the oil, but you know they aren't going to be perfect. And, lastly, can you recommend what the next things I > should replace are -- how about the dryer and expansion valve? They > are probably clogged after an A/C black death, right? And they would > prevent it from blowing cold if they were clogged right? Sorry but you are right back where you started. You have a contaminated system and you need to completely take it apart, flush every single individual component individually and properly this time, and replace the dryer, expansion valve, compressor, and all o rings, add the correct amount of PAG oil if your using refrigerant R134a or mineral oil if your using R12. If your using a rebuilt compressor you should contact the rebuilder and find out what oil they used in the compressor, if they preoiled it. Most likely if the compressor is sold as a retrofit compressor and it has oil in it, it has Ester. Then you need to put the system under vacuum for hours to get rid of the water. Ted Uh, people you are not talking about an aircraft here; there are no checklists and absolutes as much as some people would like to this is critically important work. My last moisture-filled 134a system in an '89 Rolls Spur has remained blowing cold with my purge and fill "evac" method since summer '96. What about this hypothetical: If the system is flushed as a "unit" (without disconnecting individual components other than the compressor) with a full 5 gallons of mineral spirits, the dryer, expansion valve, and orifice tube are replaced, the system is evacuated for 24 hours, and then filled with R134a, would it most likely blow cold? > > When you remove a seized compressor and the oil looks very black with > > aluminum bits in it is it called black death? [quoted text clipped - 118 lines] > > Ted >Uh, people you are not talking about an aircraft here; there are no >checklists and absolutes as much as some people would like to this is >critically important work. My last moisture-filled 134a system in an >'89 Rolls Spur has remained blowing cold with my purge and fill "evac" >method since summer '96. I assume since you can't afford a $20 quart of a/c flush that this car belongs to someone else? >What about this hypothetical: If the system is flushed as a "unit" >(without disconnecting individual components other than the >compressor) with a full 5 gallons of mineral spirits, the dryer, >expansion valve, and orifice tube are replaced, the system is >evacuated for 24 hours, and then filled with R134a, would it most >likely blow cold? If you replace the dryer and the expansion device you have already all but disonnected all the individual components. Why not just take an extra ten minutes to do it right instead of finding a way around it? Steve B. > Uh, people you are not talking about an aircraft here; there are no > checklists and absolutes as much as some people would like to this is > critically important work. My last moisture-filled 134a system in an > '89 Rolls Spur has remained blowing cold with my purge and fill "evac" > method since summer '96. The orifice tubes all have screens in them that are a much larger area than the orifice. So, if you have a little bit of crap in there it's possible that it could have been blocked by the screen, and if it wasn't covering the screen then you might get enough refrigerant past that for it to work. But if there's crud downstream it's going to go to the compressor. If your very lucky then it might all go past the compressor without ruining it then get caught in the screen. But compressors vary in the amount of crud they can deal with. A lot of the older compressor designs were like shop air compressors in that they carried oil sumps. These are the most robust. The newer compressors don't have oil sumps mainly to save space, and depend on oil in the refrigerant to lubricate the compressor - these compressors are very sensitive to the slightest amount of dirt. > What about this hypothetical: If the system is flushed as a "unit" > (without disconnecting individual components other than the > compressor) with a full 5 gallons of mineral spirits, the dryer, > expansion valve, and orifice tube are replaced, the system is > evacuated for 24 hours, and then filled with R134a, would it most > likely blow cold? You cannot have the old dryer, expansion valve/orifice tube in the system when your flushing it. If you do your just moving the junk from one place in the system to another. And also part of the usefulness of the flushing comes from the force of the flushing medium (mineral spirits) acting on the tube walls, and the turbulance in the liquid knocking all the little bits of crud loose. It isn't like the flushing liquid dissolves the crud in the hose, you mainly use mineral spirits because it is volatile enough so that you have a chance to get the inside of the tubing dried out. The reason I used 2 quarts a segment was because at the pressure and flow I was using, I would run a quart through a segment in about 5-10 seconds. By the time that anything inside would get close to dissolving the flush would be over and the inside dried out. If you leave everything connected the flow of the mineral spirits is greatly reduced, and you don't get any benefit from turbulance of it scrubbing the tube walls. Ted > Uh, people you are not talking about an aircraft here; An aircraft is a machine. A car is a machine. An air-conditioning unit is a machine. You speak as if there's some magical distinction between machines that fly and those that don't. > there are no > checklists and absolutes as much as some people would like to this is > critically important work. The "checklists" are only important if you want assurance that the finished job will actually work. Otherwise its hit-and-miss. This time, you missed. > What about this hypothetical: If the system is flushed as a "unit" > (without disconnecting individual components other than the > compressor) with a full 5 gallons of mineral spirits, the dryer, > expansion valve, and orifice tube are replaced, the system is > evacuated for 24 hours, and then filled with R134a, would it most > likely blow cold? No, because flushing it "as a unit" rams all the debris smack into the orifce tube or expansion valve, rendering the system inoperative. >In this case though, it didn't work. So, without criticizing how >stupid the techniques are (such as not replacing the dryer [quoted text clipped - 5 lines] >are probably clogged after an A/C black death, right? And they would >prevent it from blowing cold if they were clogged right? Well not to be criticizing but it doesn't work because you did a half assed job. At the very best using your method you managed to blow all the crud in to the dryer and stop up the expansion device. To fix it properly you need to remove the dryer and replace. Flush the components individually. Clean or replace the expansion device. Vacuum the system, recharge and pray you haven't ruined your compressor since you voided the warranty on it by not replacing the dryer in the first place. Your method was never a good way to do this even if it worked for you in the past. Used to be systems were very over engineered so you could cut some corners and still end up with a somewhat functioning system but those days are gone. Steve B. > >In this case though, it didn't work. So, without criticizing how > >stupid the techniques are (such as not replacing the dryer [quoted text clipped - 15 lines] > compressor since you voided the warranty on it by not replacing the > dryer in the first place. I hate to say it but that new compressor is already full of the junk she didn't get flushed out the first time. She is rght back where she started from. Bob > Your method was never a good way to do this even if it worked for you > in the past. Used to be systems were very over engineered so you > could cut some corners and still end up with a somewhat functioning > system but those days are gone. > > Steve B. > When you remove a seized compressor and the oil looks very black with > aluminum bits in it is it called black death? http://www.airpronet.com/blackdeath.htm <snip the gory details> > In this case though, it didn't work. So, without criticizing how > stupid the techniques are (such as not replacing the dryer > immediately) Recognizing you have a problem is the first step to fixing that problem.. , and knowing that the system absolutely has the correct > pressure and amount of freon in it, and the compressor IS functioning > properly, can you tell me the most likely reason the system in not > blowing cold? If your high side & low side pressures are correct (what are your pressure readings?) then it's likely the problem lies elsewhere.. not with the refrigerant circuit. > And, lastly, can you recommend what the next things I > should replace are -- how about the dryer and expansion valve? They > are probably clogged after an A/C black death, right? And they would > prevent it from blowing cold if they were clogged right? If the expansion valve is clogged, I'd expect a higher than normal high side pressure, and a lower than normal low side pressure. Your next step should be to figure out what the problem is.. what are your high side & low side pressures, amb. air temp, vent temp, engine RPM and how much superheat? "Working with thousands of A/C system service professionals, Air Pro Quality Parts was among the first to notice the increase in costly repeat-visit repairs caused by "Black Death." Air Pro Quality Parts solved the problem and significantly reduced the parts cost by packaging the necessary components in kits. They typically include a compressor, accumulator, manifold, liquid line, condenser and orifice tube." Do it right.. or do it over.. and over.. and over. It's your choice. Is this still the Benz? Regards, Jim > In this case though, it didn't work. So, without criticizing how > stupid the techniques are (such as not replacing the dryer [quoted text clipped - 11 lines] > P.S. My e-mail isn't working right now, so please reply to the > newsgroup post. Probably because flushing the drier burst the dessicant bag and spread dessicant throughout the whole system, plugging the expander valve. Even if the bag didn't burst, the drier dessicant is now flooded with solvent and won't work right. And even if the bag didn't burst, flushing the "whole" system without at LEAST removing the expander valve (or orifice tube block) simply swept all the grit and debris through the system until it reached the orifice and plugged it. You really can't say "don't criticize the techniques" because the technique IS the problem. There really aren't any shortcuts to AC service. Sorry. |
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