I'm not sure if this is the right spot for this thread, but I didn't see 1 for AC questions. o No: I'm getting ready to hook up my AC again. When I got the car, the compressor was off the motor. It has been unhooked for quite some time by the looks of it. I think it still works, but don't know for sure. Is there a way to tello No: It still turn and seems like it is building pressureo No: Also, is there anything else I should be prepared to replace on here. Is there anything that will be a MUST to replaceo No: I'll try to check it for leaks, but I really don't have a way to pressurize it (unless I can use my air compressor some how, that will put @130 lbs pressure in it) What about the drier, expansion valve and evaporatoro No: Will any of these likly need to be replacedo No: Thanks Dan:3gears:
If the lines were exposed to the atmosphere for an extended time, you may have internal corrossion of your alluminum parts, particularly your condenser and liquid line. It should be flushed with mineral spirits or lacquer thinner if so. I got a flush kit from JC Whitney for $50 that works great. You can't flush the compressor, and if you have doubts about it, replace it. If it turns easy it should be OK. You will DEFINITELY need to replace your reciever dryer and if it was open for a long time it would be a good idea to replace the expansion valve and POA valve too. If you don't have a set of guages now is a good time to get some, R-12 guages can be used with Duracool and are cheap. An air powered vacuum pump works well and is inexpensive. Using these you can check for leaks. If you don't vacuum the air out first you will have problems, so you need a vacuum pump anyway. I used "duracool" HC-12 in mine and it works great..........I ordered 2 cases of it, and can sell some to you if you need some. R-134 is a bad idea, stay away from it b/c it requires different oil and modifications in order to blow cold. Duracool does not and mixes with ALL oils. The pressure is much lower with it than 134 and it is non-toxic unlike 134 which is toxic. Duracool is also non-regulated by the EPA, as it is not CFC based. Your system is designed for mineral oil and that's what you should use. :bglasses:
I'll bite on this one. My A/C was disconnected from 1978 until 2003. Then I found all the parts and put it back together and it works. I use HFC-134a with POE oil. Now for the details: My compressor was bad, so it was a core for a rebuilt unit. I went with the stock 5 3/4 single pulley, and took it to a shop to have the electrical connector reclocked (from Chevy side to Buick side). My condensor was bad also, so I got one off a wreck, and also grabbed the liquid line. I also broke apart every fitting and took all the "o" rings in with me to have the parts counter match them up. The POA valve was lots of fun, got to buy a couple of new giant wrenches to get it apart. Be really careful that you get the right "o" rings for the small lines. There are a couple of sizes of small rings, and if it's a little too big the outer edge gets cut. I paid the money for real A/C flush solution, about $20 for a quart. I first flushed with regular solvent to see if corrosion junk came out, none did on mine, and then I followed that with the $20 stuff. It is a HCFC, and will evaporate on a warm day. Use it in the cool mornings. The trick to getting a 134a conversion to work is to reset the regulating pressure of the POA valve. My 70 chassis service manual says 28.5 psig. On the windshield end of that thing, inside, is a 7/32" adjusting nut. Put the low pressure gauge of a gauge manifold on the low service port. Use your air compressor set at around 60 psi to blow air thru it. Easiest way to do this is connect the inlet of the POA back onto the evaporator outlet, and disconnect the expansion valve at the evap inlet. Easily done since it is apart for new "o" rings anyway. Use a blow gun tip to blow air into the evap inlet (expansion valve side). Less messy if you have already flushed. The POA will attempt to regulate the 60 psi from the compressor down to 28.5 psi, and you will be able to see this on the pressure gauge, if the POA is still working. It will sound like a goose is getting "goosed". This is a way to test it. Now adjust it by turning the 7/32" nut down to 26.5 psi. This is the setting that HFC-134a likes, and results in a cold system. Now you can start putting everything back together. I used a special sealer on the "o" rings, it's a lot like honey, available at expensive parts stores like NAPA. The compressor takes 10.5 oz of oil, and I used POE because it is compatable with either R-12 or HFC-134a, and is also compatable with traces of mineral oil left in the system. Don't buy refrigerant with oil already mixed in it, like AutoZone sells. You need to know for sure that you have the right amount and right kind of oil in the system, so buy them separately. The oil gets dumped in the compressor ports just before the suction and discharge hoses get reconnected. POE oil absorbs moisture from the air, so work fast to get the system reconnected. The receiver/drier is an expendable part, you replace it every time the system is open. It will absorb moisture from the air, so don't pull the plugs until you are ready to install it and pull vacuum. I did leak testing with my old one still screwed into the system. You can use 130 psi compressor air to leak test, spray with a soapy solution and look for bubbles. Professional shops use dry nitrogen for this. If that works, you need a vacuum pump to pull a vacuum. When you do this, the vacuum will rise after half an hour or so. This is either from leaks that need to be fixed, or the moisture is boiling out. Water boils at 70-80 degrees at very low pressure, and you need all the moisture out for the system to work. Then I put the new drier on and pulled vacuum again. The book says the system takes 3.75 lbs of R-12, and the general rule of thumb says about 80% of that amount for a HFC-134a conversion. I found that when I charged, watching the vent air temp and the pressure gauges, and the sight glass on the drier, that it took about 55 oz of HFC-134a to charge my system. The rumors of really high pressures are just that, a rumor. My high side pressure is within Buick Chassis Service Manual limits for R-12. So the HFC-134a conversion does work if done right. Some people swear by "blends" such as duracool. These are blends of four or more chemicals, usually propane and butane, and when (not if) the system leaks, they leak out one at a time (fractional distillation). This changes the chemical composition of what's left in the system, as well as its thermodynamic properties. HFC-134a is not toxic, but is dangerous in that it will displace oxygen and pose a suffication hazard in closed spaces, and produces phosgene gas as a combustion byproduct. Same hazards as R-12. Another consideration is local laws. Many states do not allow "blend" conversions, and many shops don't have the equipment to handle recovery and recycling of blends, and so won't work on your car if you have a blend conversion. My advice is to stick with either R-12, or use HFC-134a like all of the automotive industry uses in the United States.
While there is a wealth of information on this board the board listed below was a great help during my buddies A/C work. A/C Board Rick
You seem to be very knowlegable John, I respect your opinion. You make a good point about shops not willing to accept blended refrigerant. Whether Duracool is blended or not, I feel that the much higher pressures R-134 produces....... along with the extra work involved changing calibrations and oils that the system is not designed for is in my opinion a bad idea and not worth the extra trouble. I would rather open my windows than put that stuff in my system. The reason the automotive industry embraces R-134 is because it is a cfc based product that can be regulated by the government, and will also have to be replaced in the future at a high cost (just like R-12 did) which will benefit the aftermarket industry in the same manner as R-134 has done......... along with the required special oils, "O" rings, reciever-driers, manifold guages, conversion kits, recycling equipment, etc. It's all about the money. Duracool is not cfc based, and can't be regulated by the federal government, it actually creates less pressure and requires NO modifications, and is the only refrigerant I will use in my Buick (aside from R-12). :bglasses:
R-134a is an HFC not a CFC. It contains no chlorine and does not deplete ozone. CFC's were phased out and HCFC's are being phased out because of thier ODP or Ozone Depletion Potential.
I stand corrected........but I'm certain that R-134 will be phased out in the future for one reason or another. I challenge anybody who hasn't tried Duracool who isn't dependant upon aftermarket supply sales to try it..........it is an excellent product that has been pushed aside by the aftermarket companies. It has the potential to hurt their sales dramatically. It is a fact they refuse to sell parts to any store that sells Duracool. That's why you can't find it in stores. They can't bully me because I am not a parts store or an a/c repair shop...........but I am very outspoken, and I believe in this product. :bglasses:
The problem with Duracool 12a is it is a blend of two types of methane and a type of propane and as of yet there is no recovery program. To be honest I'm not sure whether it's leagal or safe to vent it into the atmosphere. If it is I don't see much of a problem with it. It even has a higher flash point than 134a and like you said works with lower pressures.
I don't have any dry nitrogen, but i usually have 10-20 gallons of liquid nitrogen here:grin: That would make things very cold in a hurry:grin: Dan:3gears:
Duracool is organic, therefore it is completely safe, envirnmentally friendly, and does not need to be recovered. (unless some politician with absolutely no background in chemistry decides it does:grin: ) Also, if Duracool (HC-12) were to ignite, it would flash briefly. According to the Duracool distributor I deal with, R-134 explodes[/] and gives off more heat. With the higher pressure of that stuff, I can believe that. There actually have been collissions where R-134 has done just that, cars have burned and people have died, and the government ignores this danger. :bglasses:
Well, I know a little bit about A/C, mostly out of self-defense. There are some unscrupulous shops out there. I've got an EPA Motor Vehicle Air Conditioning technician license, but don't do A/C work for a living. I just work on my own cars, family, friends, will sometimes work for beer, and if I don't like you I won't work on your car for anything. First of all, blends such as Duracool and others do work. The problem is that states and local jurisdictions also pass laws that affect the motor vechicle air conditioning industry. Most states have passed laws banning the use of blends. And then there's the problem of shops not wanting to touch a blend converted car because of lack of equipment. Most shops will try to follow the laws so they don't get shut down. One of the things I don't like about blends is that the mixture is proprietary, i.e. the manufacturer won't tell you whats in it, in what proportions, etc. It is known that the main ingredients are propane, and butane, with other hydrocarbons. Straight propane actually has a R- number assigned to it when used as a refrigerant, instead of BBQ fuel. There is a lot of Mickey Mouse going on with refrigerants world-wide. R-12 is still produced, and used in automobiles in some parts of the world. I've heard you can still buy it at reasonable prices in Mexican border towns and try to bring it across. I've heard that European systems use propane instead of HFC-134a. Here in the USA, I've also read that HFC-134a will be controlled, and later phased out, because it is a greenhouse gas. Doesn't hurt the ozone layer, but does contribute to global warming. The conversion technology has matured and stabilized. Driers are now made that are both R-12 and HFC-134a compatible, o-rings, seals, and other rubber parts are now made of materials that are compatible with both refrigerants, as well as mineral oil, POE oil, and PAG oil. POE is the recommended oil for a R-12 to HFC-134a conversion. POE is a synthethic that is also recommended for original R-12 systems. As far as leak testing goes, the compressed air method is to be used after a system has been evacuated, before recharging. If the system still has some refrigerant in it, take it to a shop with an electronic leak detector. System pressures and temperatures - if done correctly, which means a deep long vacuum to remove all moisture from the system, the HFC-134a pressures and vent temps are within factory R-12 specs, at least on my 70 GS they are. We had a long run of 105* last summer when I wussed out and reconnected the A/C.
The only problem with that is that the ozone is roughly 18.6 miles up and R-12 is heavier than air therefore doesn't make it up that high
The problem with 134a is that it is extremely toxic, extemely corrosive and combustible. It will ignite at 351 degrees at 5.5 psi. There has been a study done at Wright Patterson Air Force Base in Dayton OH where they gave 4000 parts per million to the first volunteer mixed with air. At 4 1/2 minutes his heart stopped, his blood pressure went to zero and he lost consciousness. Clinically he died. They were able to jump start his heart and give oxygen to revive him. They thought it was a fluke so they gave it to the second volunteer he lasted 10 1/2 minutes. They discontinued all testing. To my knowledge it has never been tested again by anyone. I encourage everyone who works with 134a to do some research for themselves and their families sake. In my opinion 134a is one of the deadliest chemicals that the average person ever comes in contact with. 134a is an HFC that is hydrogen, fluorine and carbon. Hydrogen and carbon are not an issue, but fluorine is. It is the most unstable element in the whole perodic table. If you were to drop a ceramic plate into pure fluorine it would ignite. They tried to use fluorine as rocket fuel, but it cannot be controlled. Why would the automotive industry want to use it. To sell more parts. Duh. The average systems with R12 would last 10 to 15 years. The new systems with 134a are designed to last 700 operating hours. That is OK if you live in Canada, but if you live in FL it is going to be very expensive to have a/c. 80 percent of the profits in the automotive industry are made from the sales of parts. I have accumulated much more information than I could ever post on a forum in the last 9 years about 134a so if you want to know more you can call me toll free at 866 865 6233. Charles Fox
To answer your original question Dan, replace ALL the "O" rings (it really doesn't take that long, and yes you need to buy a couple of really big wrenches) and replace the evaporator/dryer. These 2 are MUSTS.
How bigo No: I have some wrenches that are like 1 1/8" and a few adjustable wrenches that will almost go to 1 1/4". Will that be big enough, or will I need biggero No: I've been following this thread since I started it. It quickly turned into a "discussion" about what AC gas is the best o No: I see that there are many opinions on that subject. Dan:3gears:
It's true that most refrigerants are heavier than air but, as they disperse the CFC molecules do find their way to the stratosphere. It's the chlorine they contain that attacks ozone molecules. CFC molecules are very stable and don't break down before they reach the stratosphere.
You'll need two of them that open to 1 1/4". One on the POA, one on the hose fitting that screws onto it. Been there, done that, and lived to tell the tale. :laugh:
Lot's of great info here. I'm putting the evaporator back into the case and reinstalling the case and assorted assemblies back onto the firewall this weekend. I replaced all the o-rings, cleaned and flushed everything out with ac flush, and I'll seal the ends of the POA and expansion valves until I get further along. Any decent sources for replacement driers?
