old car, possible retrofit AC question (r12? r134a?)

The car is a 1969 Mercedes 200. The car has AC but I cant be sure of its origin, it may be a retrofit. Anyhoo, the short and sweet is I was told by the previous owner that it was a 134a system so I picked up a couple cans and a cheapy recharge kit only to not find the AC recharge port I was looking for.

The kit has a small quick disconnect, and I've followed all the lines under the hood from the condenser to the ac pump and haven't seen ANY means of external connection (I have not looked under the dash, and have not seen an accumulator)

but then!

I saw these two ports on the compressor itself and was wondering if THESE were the ports I was looking for. If so, I'm afraid I need a "learn me". Might this be an R12 connection? how do I tell which side is the high side vs low side? Am I completely off target and need to keep looking?

The numbers say:

488-22004

509640-1291

Oil 5.9 oz

on that last one, would that be the total capacity of the system?

Cheers guys! And thanks in advance

R12 systems use threaded connections (same threads as a manifold gauge set has holding on the quick disconnect fittings), 134a uses the different sized quick disconnects. Of course it's entirely possible the mineral oil (for R12 systems) was drained out and it was refilled with ester oil (mixes with everything, 12, 134, mineral, PAG, whatever) and charged with 134a as stated, it just doesn't have the conversion fittings on it as is the standard/law in the USA for a 134a conversion.

EDIT:"oil 5.9 ounces" (fluid ounces) would probably be the oil charge for the compressor alone, the dryer/accumulator also holds a couple ounces (the oil circulates around the system). If you can find the factory charge data there is a multiplier for figuring out how much 134a to use. Or just add until the pressures look right, there's a rule of thumb for this looking at the high side pressure relative to outside temperature but I can't remember it. It will probably take 2-3 cans. That's all I remember from my brief ownership of a R12 car with broken AC and general beater car AC repair.

EDIT 2: Is that a fuel filter I see in the first picture with the hose half seated and missing a clamp?

holy crap, it is! Nice catch, and thank you

Yeah, that's a R12 system, but what is in it is another question. To Aggie Rig it in the best fashion, drain all the oil out of the compressor, put a new drier on it, add the new kind of oil, add one or preferably two of the new R134 fittings over the R12 fittings, pump it down and fill it with R134a until you get a high pressure of whatever makes you feel good.

You may be able to buy R12 over there. It would be worth the look.

In a pinch, propane will work, or you can order Freeze12 online, which is probably propane.

Toyman makes a good point, if you're cool with the whole hydrocarbon aspect of it, those hydrocarbon blends (some mix of propane and butane IIRC, Freeze 12, various "12A", envirosafe, etc.) supposedly work as good or better than 12 in a 12 system. You lose some cooling capacity running 134a in a 12 system (something about the condenser being too small?) which is probably of some concern given the climate where you are.

You can put R437a in there, no mods needed.

GameboyRMH wrote: You can put R437a in there, no mods needed.

And where does one buy this magic elixir?

I am pretty sure you need to replace all the o-rings in an R12 system if you want to run 134. Hoses should be fine though, apparently they get clogged up enough with oil after having run R12 for a while not to leak. You theoretically should replace the expansion valve also (generally a lot of work) because of the pressure differences.

I have run Envirosafe (which is some sort of 134 blend) in an R12 system, worked fine (way cheaper then R12). That would be my suggestion.

spitfirebill wrote:

GameboyRMH wrote: You can put R437a in there, no mods needed.

And where does one buy this magic elixir?

Now that I look it up it turns out R437a isn't sold in the US...that explains why it isn't more commonly used in place of R134a.

In reply to GameboyRMH:

Bill isn't in the States at the moment. He's in the Middle East IIRC.

Ah OK, this is the closest supplier I can find:

http://www.eurorefrigerant.com/14-r437a-r413a-isceon49-ex-r12

aircooled wrote: I am pretty sure you need to replace all the o-rings in an R12 system if you want to run 134. Hoses should be fine though, apparently they get clogged up enough with oil after having run R12 for a while not to leak. You theoretically should replace the expansion valve also (generally a lot of work) because of the pressure differences. I have run Envirosafe (which is some sort of 134 blend) in an R12 system, worked fine (way cheaper then R12). That would be my suggestion.

This is what I came here to post. I always thought the O-rings used in an R-12 system would essentially disintegrate in the presence of whatever different oil was used on an R-134a system.

I have never actually heard of anyone changing from R12 to R134 that had O-ring problems. Now, 30 year old AC systems may have O-ring problems all by themselves, and R134 runs at a higher pressure, so I could see that an O-ring issue could arise, but I seriously doubt it is from a different chemical. If you have a joint apart, it is always a good idea to put a new O-ring in it. A complete set of every O-ring you will ever need for an AC system is cheap from techchoiceparts.com.

In reply to Dr. Hess: That looks like a good source. Just bookmarked it.

GameboyRMH wrote:

spitfirebill wrote:

GameboyRMH wrote: You can put R437a in there, no mods needed.

And where does one buy this magic elixir?

Now that I look it up it turns out R437a isn't sold in the US...that explains why it isn't more commonly used in place of R134a.

Gee, I wonder if DuPont has anything to do with that?

Yeah, "I wonder" if DuPont had anything to do with R12 being pulled and R134a put in its place? Couldn't be that R12 was selling for a buck a pound, IN THE berkeleyING CAN, RETAIL PRICE AT VATO-ZONE and any patents had long run out, could it? I will also point out how DuPont got its start in this country. The Brothers escaped France before being beheaded during the revolution, stepped off the boat in the US and were handed a million dollars (a considerable sum in those days) to start a black powder factory for the US Government.

Anyway, TechChoice is a good place for AC parts. I bought a new Sanden compressor for the Esprit (RIP) from them for like almost free compared to everywhere else, plus the expansion valve, drier (same as a RX7, if I recall.) Very knowledgeable people to talk to as well. I told them I wanted to go with R134a and they fixed me up.

Can you get R-12a there? It will run in an R12 compressor and at the same pressures I believe, also- you don't need to pull a vaccum, it actually likes a spot of water in the system. it's mostly propane.

Thanks everyone! I'll try to catch this all in one go

So yeah, I'm in Kuwait but finding R12 might still be an issue. Being relatively new I'm having a hard time finding out where to get what. (for instance, I bought oil for my car in an alley). I do have access to amazon and they stock R12a, so I think that's is what I've decided the best route for me is going to be (the downside to amazon is it takes FOREVER for stuff to get here)

I think I see the leak in this beast. Look under the fuel line in the next picture (I'll try to take a better one in the future) You can see the AC hose is wet behind the metal-to-rubber crimp.

Another shot. Top dead center of that last picture, I'm going to have to replace that I think...

Until I can get the parts/tools together to do that, I think the best option right now is going to be to use the 134a I have to get me through the summer months. Unfortunately, my re-fill kit I bought doesn't have the threaded connection to the quick disconnect for me to adapt. Instead it's a crimp (see below)

I figure I've got one more shot at getting this right before I'm in the "maybe I should just pay a professional" category, but I had a few more questions:.

Those ports: Somewhere I read during all this research that R12 ports should differ slightly and the high-pressure side should be larger. These ports are exactly the same... Did I read wrong? or is my car wrong?

if I read wrong: how do I determine which is the high pressure side, and which is the low pressure side?

On the subject of recharging: Without a pressure gauge, how do I know when to stop? Can I safely assume there to be a pressure relief system? On my wife's old Corolla I tried to add a can when it didn't want one and it burped off the excess. Should I amazon a set of r12 gauges and be safe?

I'm going to go looking for a hardware store tomorrow (still on foot, cant drive here yet). Rumor has it, there's one near my hotel called AGO or APO or something like that. I'm going to see if I can find a barbed fitting that will screw into the fittings on my ac pump. I figure I can bring a cap and try to match it the best I can.

Once the hot season is done (October) I'll vacuum the system out, repair leaks, and recharge with R12a.

Cheers! And thanks again

This is really a job I wouldn't want to do without a manifold gauge set, I think the R12 fittings are standard SAE 45* flare stuff. If you look on top of the accumulator/dryer there should be a small window on top, that can be used to gauge the charge level, I think you fill until the bubbles stop? You can find high and low by following the hoses.

If I had to guess, the left port on your picture is the low side. The low pressure side is the one closest to the bigger diameter hose.

The left one on this picture.

The different size ports happened with 134 conversions I think. Older cars don't always have them and I use the same method as slippery, look for the Larger OD pipe.

You guys are awesome! I didn't even think to associate the ports with the hose size.

In other news: Gauge set found!!!. It only took me 2-days and three tries on foot in 100+ degree weather to find a used one. Unfortunately I still need a can tap to make it so they can charge the system. Ebay has em for about $10. I may go that route.

I need to get under the hood again I don't remember seeing an accumulator, dryer, expansion valve, or an inline filter. I'll poke my head under tomorrow morning and let you guys know what I find first thing in (my) AM.

Cheers!

(Pictures of this awesome gauge set that really had me beat. I'll put the full story in my Build Threadinterested enough)

(oh yeah, I also found a suitable case. Out the door, I left the market with $33 less in my wallet. I got a few other things as well)

Good news! Found the.... thingy! (Accumulator?)

Still waiting on the can tap and adapters but I didn't want y'all to think I was slacking or anything