a/c Challenge

[Dibbs]

I have been told so many different things by so many different people, be it Auto parts, mechanics, a/c techs, or people like yourselves, all different approaches to the r12-134 conversion. I've been told everything. Some say I need a new compressor, some don't. Some say I need to replace the dryer and again some don't. Others say I need to replace the o-ring seals on the tubing connections and again.....some don't. I finally said screw it, bought the conversion kit and juiced it up. There was no need to pull a vacuum on the system b/c it was bone dry. I let the car sit up for 2 years and the freon leaked out during that time. I am fairly confident that since the a/c was in good order when i left it, that the seals shrunk up and over time the freon leaked out. Well, it's been 24 hours so far, the car is holding the freon and it blows quite cold.


But my challenge to all of you is...to give a consistent procedure how to succesfully prepare and convert the a/c system to 134 for my '86 lx-i hatch.

Even if I screwed up by charging my system and not replacing something, I'll just wait until the system runs out of freon and correct the problem. I live in Texas. I drive an hour to and from work and I'm quite tired of driving in 95 deg. weather w/ no a/c. :burn:

[88Burner]

Generally, it's not required to replace the compressor. However, on our cars, a replacement would be a welcome one. The receiver/dryer MUST be replaced. Just because the system was bone dry doesn't mean it shouldn't have been evacuated via a vacuum. If the retrofit is done properly, the system should have been checked for leaks, evacuated, etc. You don't want to mix the two refrigerants and the oils. The compressor for 134a will require the correct ammount of PAG oil. So... if you dont have the money to change the compressor, or whatever the deal is... just make sure you at least change the compressor oil, receiver/dryer, and service valves and evacuate/vacuum it.

[DBMaster]

Well, the problem is that even A/C professionals have varying opinions on how this should be done.

Number one, if you have the Keihin compressor it WILL NOT hold up with R134a. It has seals made of a material called "Viton" that will deteriorate rapidly. Basically, you are looking at a system that will not hold refrigerant any more once it goes. How long that takes, I don't know.

You definitely need to pull a vacuum on an "empty" system. At best, your system was filled with air. At worst, there was some moisture in the system that will become corrosive once exposed to the new refrigerant. You also need a new drier because the dessicant used in R134a system is different from the dessicant used in R12 systems.

You should not need new o-rings or hoses. The current thinking is that the R12 hoses absorbed so much oil during their lives that they now "act" the same as the barrier hoses needed for R134a. The old rubber hoses that were not lined with a "barrier" material would allow the smaller molecules in R134a to leak right out through the rubber.

As long as you put some PAG oil into the system you may be OK. The old oil will not hurt anything, but it will also not lubricate your system as it does not "mix" with R134a. It will just settle into the low spots in your system. Without some PAG oil the compressor will eventually seize from lack of lubrication.

Lastly, the performance of R134a in our systems is thoroughly mediocre. We do not have the type of condensor needed for maximum efficiency (read that "cooling"). You will also see a severely shortened service life of major components. I guess it might be better than no air, but on a really hot day you'll be hurting.

Since it is very easy (albeit more expensive) to obtain R12 I always recommend sticking with that until the bitter end. If you are set on converting to R134a do it right (you'll have to drop quite a dime up front - no $35 kit from Wal Mart). Or, just throw the crap in there and enjoy the semi-cool air for a year or two and plan to get rid of the car when it fails.

[Dibbs]

well.....lets say I get a new dryer....should I vaccum the old stuff out and basicly start over? Also, does anyone know what the correct amount of PAG oil is, or do i just have to pour it into a measuring cup?

[DBMaster]

Can't help you with that one, Dibbie. Supposedly, the little can that comes with the cheap "retrofit" kit has enough oil in it. that's yet another problem with the conversion. You have to add more oil to the system on top of oil that is already taking up space that could be taken up by refrigerant. It won't need much. I would still recommend that you go with R12. I would put this stuff in my system before I would think about R134a because it says it will work with the existing mineral oil and runs lower pressures.

http://www.autocool-refrigerants.com/

It all depends upon how long you want to keep the car (with functional A/C). I am probably not the one to talk with about bargain basement fixes. I spent $1,000 four years ago to get the new compressor kit (Sanden) from Honda. It came with the compressor, hoses, brackets, and drier. I went with R12, of course. Mine puts out cold air like when it was new and so far has lasted four years. It was worth it to me because the car is immaculate and I planned to keep it for a long time.

There seems to be no "one" right way to change refrigerants. You just need to talk with someone who has done a lot of retrofits and that has been doing them for a while. You can usually talk to the shop and "ask" them what they recommend for your car. Then, you have the option of doing it yourself.

Good luck and stay cool.

[Dibbs]

Thanx for the help. It was 95 deg for the drive home yesterday and it took about 15 min to cool the car down so I see what you mean about using the r12, especially for us who live in Texas.

[88Burner]

R12 is actually a better refrigerant than R134a. It just so happens that R12 is more harmful to the environment, which is why they switched to R134a. The price of R12 is going up. The Honda service manual or service bulletin should say the right ammount of oil... don't know off hand.

Dibbie, either way it'd behoove you to get your system evacuated and pulled into a vacuum. A good shop will first identify exactly what is in the hoses. It'll tell em what percentages of air, r12, r134a, propane, whatever is in the lines. You also don't want all the refrigerant to leak out. Shops sometimes will inject a non-harmful dye into the hoses that can be seen with a black light. Then if there's a leak they can find it. You're looking at spending some money if you want a good reliable system.

Propane is actually a decent refrigerant... and some shady shops have put propane in a/c systems. I wouldn't wanna get in a wreck with an a/c system full of damn propane.. crazy stuff.

[DBMaster]

Actually, the price of R12 is coming DOWN, at least on eBay.

You see, every year that goes by means fewer devices out there that still use R12, thus the demand has dropped dramatically.

The degree of how harmful R12 is varies depending upon which "expert" is consulted, but the plain fact is that our A/C systems will not perform satisfactorily with R134a without some fairly expensive modification. Now that I realized that Dibbie is in Houston I know that he would be especially unhappy. The high humidity down there means even poorer performance when the temperatures get up into the mid to high 90's.

Maybe if you get the correct compressor, drier, hoses, condensor (ours is not really large enough to work well with R134a), and expansion valve and then evacuate the system and recharge with the proper oil and R134a you might feel like the A/C is decent. That would end up costing you more money than fixing what is currently wrong and paying the price for R12. Just make sure you don't have any leaks so you don't lose that expensive stuff.

[rustyaccord]

#1 Do not use PAG oil. It is incompatible with r12 and the old mineral oil.

#2 Add about 4 oz of POE/Ester oil to the system. (It's probably best to drain the compressor oil and refill accordingly, but not required - if your system was working properly before, don't flush or work to get all the old oil out as it helps to seal all the old lines)

#3 Vacuum the system or use the "purge" method, which is probably illegal, and not as effective (you figure it out) Vacuum is best - but not even shops with the right tools do it well - they just have no idea of the reason they are doing things, and will do things like run the vacuum pump with no oil, they feel "suction" so they figure it's good. You need a good vacuum pump to pull 29"+ of vacuum and hold it for an hour, otherwise it's next to useless. (I hear you can rent them easily - just not up here in new england - bah)

The vacuum removes moisture, air and r12 - air can't be condensed and just raises system pressure and lowers efficiency. An r12-r134a mixture will also raise pressures (less than 5% r12 is negligible, iirc). r134a will run higher pressures anyway, so this is a very BAD thing, for your compressor. Moisture and r12 would combine to form acids in the system, I am not sure about the r134a, who's a chemist here?

#4 charge with 80-90% r134a BY WEIGHT. I believe all 3g's are spec'd at 24-26oz r12, so you want to add ~20-23.4oz. This means LESS than two full cans. This is a big problem for our cars as they are easily overcharged, leading to compressor failure, or just poor cooling. Make sure to purge the charging hose of air before you plug in. Air and moisture are bad.


I've done an 87 lx, still going strong after a year, on a 90+ day noon on the highway the air gets cold enough to cycle off the compressor (~35ish F) at full blast, and just did my 89. No dryer changes. (If the system has a few percent r12 in it, it should still be effective enough, not to mention it's just not necessary on a dry system. Besides being a reservoir it has a desiccant pack in it, like you get with shipping boxes - it can either be incompatible with r134a, or just be 'full').


To those who complain about poor performance - none of the 'expert' recommended changes will help you beyond the above (though it will help a few people's wallets). The only other things to do are to get an oversized condensor - it will compensate for the low efficiency and lower system pressure leading to longer compressor life (You might even be able to add some more r134a...) and to get a r134a specific expansion valve/orifice tube. My feeling is that all you need to do is change the condensor if you live in a really hot area or do a lot of stop-n-go traffic. (Just cleaning the old one out well would probably improve a lot of people's impressions of r134a) Highway drivers shouldn't be able to tell the difference I think.

[Dibbs]

thanx 4 the help everyone. this thread has really gone to prove my point about how everyone's ideas are different from others,
albeit minor in some cases. But again, I appreciate it. I still got most of my questions answered and that's the idea...right?

[DBMaster]

Well, here are my two cents.

If you can get R12 (It ain't THAT expensive) why wouldn't you want to stick with that? It is the optimum refrigerant for the performance and longevity of your system.

I am done with my comments. :)

[rustyaccord]

Originally posted by DBMaster
Well, here are my two cents.

If you can get R12 (It ain't THAT expensive) why wouldn't you want to stick with that? It is the optimum refrigerant for the performance and longevity of your system.

I am done with my comments. :)

My r12 leaked out when my low side valve core gave out. So I bought new r134a fittings with valve cores, converted to r134a. Just my luck, the new valve core on the low side leaks like crazy.. two cans of r134a gone in 24 hours. How much would that have cost me as r12? Instead I paid $4.88 per at walmart :)

I guess it's not a big deal if you don't work on your car yourself, ever.

[DBMaster]

Where did you get the idea that I do not do my own work? I do almost all of my own work. I have replaced about four auto A/C systems. It was just that when I got my A/C done the cost was actually not much more than the parts and I got a warranty on the work.

The leak issue is why you actually have to FIX the system first. You don't want to put ANY type of refrigerant in a leaky system. If you shop around it can cost you $100 for R12, you are right about that, but it will cost a lot more to replace the parts of the system when they go bad. If you put a vacuum on the system after doing repairs you should be able to tell if still have leaks.

R134a will not perform satisfactorily in my system in my climate, period. Since I can afford to fix the car the right way, I do. If I were going to go cheaper I would try Autocool before I would use R134a.

[rustyaccord]

Originally posted by DBMaster
Where did you get the idea that I do not do my own work? I do almost all of my own work.
...
If you put a vacuum on the system after doing repairs you should be able to tell if still have leaks.

R134a will not perform satisfactorily in my system in my climate, period.

Because you need to be licensed and possess $3000 recovery machines to legally work on r12, otherwise you take it to the local garage.

My leak would not have been detected in the usualy method where you leave the gauges attached and pull a vacuum through it. Second, if it was known there was a leak, there would be no way to pinpoint it. Inevitably some refrigerant and a sniffer or UV loaded refrigerant and a black light would have to be used.

It would with an upgraded condensor.

[DBMaster]

I see...

I am licensed, but I do lack the recovery equipment. A bit of a hole in that system, if you ask me. I did all of my system replacements before the current regs went into effect in 94-95. The only reason I let a shop install my current A/C is that I knew the kit to upgrade to the new compressor from Honda was $750. They charged me $1,000 which included labor and Freon. Seemed like a good deal at the time.

I have enough experience with the Honda systems to know that ANY TIME you have to evacuate the system go ahead and replace the schraeder valves on the high and low side. They are cheap enough and I have lost enough high priced R12 to have learned my lesson there.

Even on boards that have a lot of real A/C experts there seem to be diagreements about 134 conversions. I will not do one on this car, that is my personal choice. By the time I need to worry about it again I will not own a car that uses R12. Of course, by then the demand for R12 will have dropped so low that you'll be able to pick it up for cheap again. (Maybe not 89 cents a can, but certainly less than $35) The prices have already dropped into the low 20's on eBay. Every year there will be fewer and fewer pre-1994 cars on the road and quite a few of those will have been converted. Ever since they started using compressors that cycle on and off in the early 80's they started not lasting. The old style compressors, like the Frigidaire on my old Pontiac, had a clutch that stayed engaged all the time and it was still going strong after 18 years and 212,000 miles.

Later

[offthahook]

Question about freon... Do junkyards recover any R12 in wrecked cars?? COuld it be reused IF the front end was intact? I thought I read where thay have to "drain" it anyway before they can put it in the yard. I dunno, could it be reused if it were tested and found to be uncontaminated??

[wthramann]

I have been led to believe that there is so much virgin R12 still available that it has not been necessary to use recycled freon yet.