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#1
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Replacing AC condensor - what if I don't evacuate system beforerecharge?
I'm replacing the AC condensor on my 300m. The car originally had
R-134a (.71 kg or 25 oz or 1.56 lbs according to the manual). I'm looking at getting a "Red Tech" recharge kit. It contains "12a" refrigerant and claims to be compatible with R12 and R134a. A 6-oz can claims to be equivalent to 18 oz (of R134 I suppose). A kit contains 2 cans so that should be enough to charge an empty system. So I'm wondering what happens if I don't use a vacuum pump to evacute the system prior to using the recharge kit. I'm also wondering if I'm going to have to add lubricating oil somehow. The service manual says the oil type is ND8 PAG, total quantity = 150 ml (5 oz). |
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#2
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Replacing AC condensor - what if I don't evacuate system before recharge?
On Fri, 29 May 2015 22:45:35 -0400, MoPar Man > wrote:
>I'm replacing the AC condensor on my 300m. The car originally had >R-134a (.71 kg or 25 oz or 1.56 lbs according to the manual). > >I'm looking at getting a "Red Tech" recharge kit. It contains "12a" >refrigerant and claims to be compatible with R12 and R134a. A 6-oz can >claims to be equivalent to 18 oz (of R134 I suppose). A kit contains 2 >cans so that should be enough to charge an empty system. > >So I'm wondering what happens if I don't use a vacuum pump to evacute >the system prior to using the recharge kit. > >I'm also wondering if I'm going to have to add lubricating oil somehow. >The service manual says the oil type is ND8 PAG, total quantity = 150 ml >(5 oz). With a new compressor I've always added oil as specified. With the R12 systems I had good luck not evacuating (didn't have a pump) but only had the vehicles 3-4 years after replacing the compressor. With R134 I've vacuumed every time. The pump cost me about 110 bucks. I've had such poor results with rebuilt compressors (3 of 3 went bad quickly) that I only use new compressors now. They've lasted. You should evacuate. No experience with Red Tech. Regular R134 has worked fine. |
#3
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Replacing AC condensor - what if I don't evacuate system beforerecharge?
MoPar Man wrote:
> I'm replacing the AC condensor on my 300m. The car originally had > R-134a (.71 kg or 25 oz or 1.56 lbs according to the manual). > > I'm looking at getting a "Red Tech" recharge kit. It contains "12a" > refrigerant and claims to be compatible with R12 and R134a. A 6-oz can > claims to be equivalent to 18 oz (of R134 I suppose). A kit contains 2 > cans so that should be enough to charge an empty system. > > So I'm wondering what happens if I don't use a vacuum pump to evacute > the system prior to using the recharge kit. > > I'm also wondering if I'm going to have to add lubricating oil somehow. > The service manual says the oil type is ND8 PAG, total quantity = 150 ml > (5 oz). Probably not a good idea to mix air and propane/iso-butane. I would evacuate the system. btw, R12a is banned in 18 states. |
#4
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Replacing AC condensor - what if I don't evacuate system before recharge?
On Friday, May 29, 2015 at 4:44:48 PM UTC-10, MoPar Man wrote:
> I'm replacing the AC condensor on my 300m. The car originally had > R-134a (.71 kg or 25 oz or 1.56 lbs according to the manual). > > I'm looking at getting a "Red Tech" recharge kit. It contains "12a" > refrigerant and claims to be compatible with R12 and R134a. A 6-oz can > claims to be equivalent to 18 oz (of R134 I suppose). A kit contains 2 > cans so that should be enough to charge an empty system. > > So I'm wondering what happens if I don't use a vacuum pump to evacute > the system prior to using the recharge kit. > > I'm also wondering if I'm going to have to add lubricating oil somehow. > The service manual says the oil type is ND8 PAG, total quantity = 150 ml > (5 oz). The pump evacuates the water from the system. Water in the lines would tend to freeze in the evaporator and might clog up the orifice. I think that water also reduces the cooling capacity of the cycle although I might be wrong about that. |
#5
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Replacing AC condensor - what if I don't evacuate system beforerecharge?
MoPar Man wrote:
> I'm replacing the AC condensor on my 300m. The car originally had > R-134a (.71 kg or 25 oz or 1.56 lbs according to the manual). > > I'm looking at getting a "Red Tech" recharge kit. It contains "12a" > refrigerant and claims to be compatible with R12 and R134a. A 6-oz can > claims to be equivalent to 18 oz (of R134 I suppose). A kit contains 2 > cans so that should be enough to charge an empty system. > > So I'm wondering what happens if I don't use a vacuum pump to evacute > the system prior to using the recharge kit. > > I'm also wondering if I'm going to have to add lubricating oil somehow. > The service manual says the oil type is ND8 PAG, total quantity = 150 ml > (5 oz). Why the switch? R134a is available just about everywhere. The system was designed for it and there is no guesswork about the charge. R12a is NOT a drop in for 134a either, it is an alternative for R12 in industrial applications and is illegal for use in mobile A/C under federal law. As for evacuating the system, if you don't there will be moisture and air in the system which will cause problems. You will also need to replace the drier and flush the system as the drier is not compatible with the oil that R12a, Also you will need to change the hoses to barrier hoses as the butane will actually leak through the hoses made for 134a. -- Steve W. |
#6
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Replacing AC condensor - what if I don't evacuate system beforerecharge?
"Steve W." wrote:
> Why the switch? R134a is available just about everywhere. It's not that I want to switch - it's just that I don't know if 134a recharge kits are available in Canada. These "Red Tek" kits (r12a) are. r12a (which is mostly propane?) seems to be a more efficient refrigerant. Can result in lower air temperature and less power required from the compressor (lower operating pressures too). > and is illegal for use in mobile A/C under federal law. I could give two ****s about any laws. If it's available and it works - I'll use it. > As for evacuating the system, if you don't there will be moisture Red Tek apparently sells a dehydration treatment which "converts system moisture into an inert silicone oil which combines with the lubricating compressor oils". So if the dehydrator works, then the only issue is some small amount of air in the system (which is mostly what - nitrogen?). I suppose I could use the dehydrator, then add the r12a to excess, then bleed some of it off (thereby reducing the amount of "air" in the system). Either that, or I spend $150 on a vacuum pump and gauge kit. > You will also need to replace the drier and flush the system as > the drier is not compatible with the oil that R12a, Red Tek doesn't mention if their product has oil. > Also you will need to change the hoses to barrier hoses as the > butane will actually leak through the hoses made for 134a. Do you have a reference for that? The (somewhat minimal) wiki page for HC-12a does say: "Some advantages to using the HC-12a mixture over retrofitting to R-134a are cost and labor. Since HC-12a is a "drop-in" replacement, no seals need to be replaced and minimal effort has to be put in to changing the refrigeration system around." It also says that r134a, when combined with refrigerant oil is just as flamable as hc-12a. |
#7
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Replacing AC condensor - what if I don't evacuate system before recharge?
On Fri, 29 May 2015 22:45:35 -0400, MoPar Man > wrote:
>I'm replacing the AC condensor on my 300m. The car originally had >R-134a (.71 kg or 25 oz or 1.56 lbs according to the manual). > >I'm looking at getting a "Red Tech" recharge kit. It contains "12a" >refrigerant and claims to be compatible with R12 and R134a. A 6-oz can >claims to be equivalent to 18 oz (of R134 I suppose). A kit contains 2 >cans so that should be enough to charge an empty system. > >So I'm wondering what happens if I don't use a vacuum pump to evacute >the system prior to using the recharge kit. > >I'm also wondering if I'm going to have to add lubricating oil somehow. >The service manual says the oil type is ND8 PAG, total quantity = 150 ml >(5 oz). See if you can rent a vacuum pump. It's really a LOT better to pull a vacuum when you do this. You can probably get away with out doing it but run the risk of the moisture creating acids and corroding the system or the moisture freezing and plugging up something. I've used stuff called Freeze12 and ES12a and it's worked fine (I always pulled a vacuum) and as you already noted, the number of ounces has to be converted. You probably should add 2 ounces of whatever oil the system is suppose to use. If possible drain out the oil from the old condenser and measure it and add that much new back in, maybe plus a little more is any leaked out while you were unbolting stuff. You can just pour the new oil into the new condenser before you hook it up or pour it into one of the open lines before reconnecting them. As other mentioned, if you can get 134a it would be better to use it, the system is calibrated for it... but that other stuff should work fine too. Also, just had a thought.. if your system is not taken apart yet and you won't be pulling a vacuum, as soon as you disconnect things cap off the lines so you get as little air as possible into the system, let it keep as much of the old 134a vapor as possible. |
#8
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Replacing AC condensor - what if I don't evacuate system before recharge?
I don't know what R12a is, but somewhere I remember reading that the R12 replacements are blends of different materials with different volatilities, and therefore, that tiny leaks change the composition of the refrigerant, making it change its properties with time. I have no clue if this is true or if it matters.
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#9
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Replacing AC condensor - what if I don't evacuate system before recharge?
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