1970-W30

In the process of installing a new engine I had to support the compressor to get it out of the way. Now the system is not blowing cold air, compressor clutch engages, compressor runs, but there is hardly any temp difference between the high side and the low side lines when comparing the two outlet ports. Maybe the AC system just had a very slow leak, since it hasn't been used since last October, or the change of the hose fittings angles caused the system to leak the freon when I moved the compressor.
Anyway,I have a can of R12, thought I would charge it and then check for and find where the leak is, but then I noticed that while the high side has the male thread old conventional R12 style port, the low pressure port located on the POA valve is a quick disconnect style with internal threads like the converted R134a systems use. Could this system have been converted over? How can I tell if it has been changed? I certainly do not want to dump R12 into an R134a system.
If the high side port, which is part of the hose assembly, would have been a quick disconnect style also then I would be reasonably sure it is a converted system, but now I have my doubts ......... Any AC experts out there?

Lady72nRob71

Given that adapter is on there, i suspect something other than R12 is in it. Could be 134, freeze 12, or who knows what.
Do not add your 12 until you can really find out what's in there.
Do you know the previous owner? Long shot but had to mention it...

Check the valve cores in the fittings to see that they are tight. A regular tire valve tool can be used. Mine were all loosey goosey so mine escaped.

MaxDog

Not sure what exactly you have unhooked, but if the system has been upgraded, the new system should have green o-rings I believe.

1970-W30

I haven't unhooked or taken anything apart, took it to an AC shop who said a hack probably dumped 134 in and that I wouldn't have much to lose if I would recharge with 134 again. This is the 3rd shop I have contacted, none have R12 equipment anymore and can't properly recover the R12, basically telling me they don't want to mess with it.
I see a Vintage Air conversion kit in the near future coming up...... it would be nice to see a flat firewall on passenger side......

classicmuscle442

You would need to have a set of refrigeration gauges to put on system and with gauges installed, have a accurate temperature gauge to measure outside temperature and a refrigerant pressure chart. At a certain temperature refrigerant has a certain pressure. You do not need to operate system to check. With the chart you convert temperature to pressure and match it to the different refrigerants to find the correct refrigerant. Some heating and cooling guys can do this, refrigeration guy for sure. Hope this helps, this doesnt take into account that their could be a mix of differant refrigerants in system. The type of R-134a adapter on the low side tap would make me think its 134a. chris

jag1886

Time to go to a air shop. I would bet you have a mix of 2 types of freon. Have a shop suck down the system, then change the oil in everything add a new drier, fill it up with R12 and see what happens. That's what I did and mine works great now.

NorTown Olds

I agree, sounds like this very well could be what is going on.... GOOD luck, let us know what happens!

1970-W30

Here's the plan so far, Iv'e ordered a recharge kit utilizing Duracool as the refrigerant. It is a hydrocarbon type of refrigerant that is compatible with any type of oil and /or any type of freon that might have been in the system now. Since AC shops don't want to deal with R12 recovery and the systems almost empty (i'm assuming), i'm going to empty it out, put it under a vacuum and refill with Duracool. According to their info, Duracool molecules are much larger then either r12 or 134 freon, lessening the possibility of leaks...Will let everybody know if it's succesful or not, nothing ventured nothing gained.....

rocketraider

Trouble with that is most are not going to want to vacuum a system they don't know what's in it and run the risk of contaminating their recovery unit.

I'd find somewhere secluded and vent the system to atmosphere. Then take it to the shop, empty, and see if they'll work with you better. If it means rebuilding the system, at least you're sure what's in it.

That was another great fallacy of the R12/ R134a boondoggle, and to this day I still don't believe 12 had the effect on the ozone layer that was claimed. What I do believe is that DuPont, knowing their R12 patents were expiring (no more royalty money), "influenced" the EPA to mandate phasing it out in favor of 134a- which no one was interested in because it didn't cool as efficiently.

at3reg98

The port should have an adapter with a blue cap for R134. They use a different schrader valve. I also don't think R-12 was as harmful as the tree huggers claim from what I've read. I have that R-134a in my '83 and it's going back to R-12 so I can freeze like I should in the summer. Most of the R134 has leaked out anyway. The R-12 is still widely available on ebay. The conversion is the easy way out due to service (if you get a shop involved) and availability. If you want real ice cold A/C, do some reading online, tackle it yourself and put the R-12 in. There are step by step sites out there. Just my 2 cents.

Mike77

There is no MAGIC gas that will do what what you say. It's pure laws of thermal dynamics. If you have gas already in the system it needs to be removed befoer adding anything else. Look up the "Boyle's law of partial pressures". A reclaim unit is all you need , not something "special" for R-12. All reclaimed gas is taken to facility and destroyed. I have all kind of different gases in my reclaim tanks. You need a proffesional service tech. Have the gas reclaimed, leak tested, and re-charge with and approved gas. Some POA valve recalibration for R-134a. All your going to do is mess up the system and spend a bunch of money the way your going about it.

PS
it's the chlorine in the R-12 that cause the destuction of the ozone molecule. Ozone is 3 oxygen molecules and is very unstable.

Mike

MDchanic

That stuff may work, or it may not.
Hydrocarbons are viable refrigeration gasses, but have not been used in refrigeration for a very long time because of their high flammability (accident may = BANG!). Other well known hydrocarbon gasses include propane and acetylene.
This particular gas, as seen in the company's MSDS, would appear to be n-pentane (from its boiling point of -36.2C), which is a string of five carbons, each with two hydrogens, with an extra hydrogen on each end:

It IS a larger molecule than the other refrigerants.


It is of course very illegal to vent refrigerants to the atmosphere, so we know that you didn't rally mean to say that, and that is not what you are going to do, though you may have made a mistake, and there really is no refrigerant left in there at all.


- Eric

1970-W30

Eric, you're right I must have miss-typed, the system is empty of course, I certainly wouldn't want to be responsible for messing up the ozone layer by releasing any harmful chlorine into the air. Never mind the fact that the thousands of pools here in the Phoenix area alone all use chlorine tabs in the pool water that release chlorine gas 24/7 year round that must really play havoc with the ozone layer. Anyway a complete refill will be $57 and I don't have to worry about the type of oil that is in the system. Way cheaper than R12.
Mike, this Duracool is not some type of "magic" gas, it's a proven very efficient refrigerant. The reason it isn't used is as Eric said, it's flammable like your home BBQ propane tank or a smokers butane lighter he carries in his pocket.
The system is now "empty", ready for a pull down when the stuff arrives.

MDchanic

No wonder it's so hot there!

- Eric

jag1886

You are dealing with the wrong air shops, good air shops still use R12 regularly and recommend using it on older cars that came with it. My 65 car had been changed over to R134 (kinda), it did cool with the R134 but now after changing back to R12 it about runs you out of the car.

I know air work is expensive, I hope the Duracool works for you, Good Luck.

Mike77

The ozone depetion is a little more complicated than the pool theroy. Basically the chloride wants to say at sea level. It needs help getting to the upper atmosphere
The other chemical in refrigerant, methanes flourines hydrocarbons etc carry the chlorine up. The real problem is it takes 50-70 years for the moleculer depletion to complete. The effect we see now is release from 1940-1960. We dumped way more from 1960-1996.
On the refrigerant product there a a wide variety of blends availble. Some good, lots not so good. Stick with tried and true. A lot of blends have flammables. Be careful.

1970-W30

Well my Duracool shipment came in yesterday, I just finished pulling the system on a vacuum for a while and then recharging with 3 and3/4 6ounce cans, the equivalent of 4 lbs of R12 which is what the system holds. Temperature is 39 degrees, at fast idle in a 70 degree garage. I'm happy with the results..... The kit comes with 134a adapters, safety goggles and a oil condition sampler, which I thought was pretty cool. Just push on the low side tap for a second or so with the sampler and then check the color reading to see how acidic and contaminated the oil is. Mine passed OK, Yippee!! Total cost of kit was $57.88 including shipping. Ok I did buy a gauge set at Harbor Freight with the 20% off coupon, i'm still under a hundred bucks all in. So now if it leaks say a can a season, less then $10 for a recharge.
The only problem now is that the blower speed seems to be the same at the high speed setting or the next setting down, any ideas what would be the culprit?

gregvm

There are direct drop in gasses that work as advertised. I own a business that uses commercial refrigeration(coplematic 7.5's), which were designed to run on R-12. When the ban went into effect, I recovered and converted to "enviro-safe" r-12. Works like a charm. No oil change, no expansion valve replacements/adjustments.....Coolers refrigerate faster/colder, and it cut my electric bill by 1/3. No brainer...That was years ago already....still running...

1970-W30

Glad to hear that Grevm, that's exactly why I went this route, lower head pressure, no modifications, better cooling and way lower costs. I just couldn't justify the outrageous R12 prices which will only go up as time passes plus I wasn't sure it what it had in it.