Question on R12 vs R134a for '69 A/C

[Michael L.]

[Don H.]

Re: Question on R12 vs R134a for '69 A/C

Hi Mike, I am not an AC expert but this is what I've been told over the years. Oil: Mineral=R12, PAG=134, Ester=Either. Over 20 years ago I had 134 in my '65 (factory AC) but I converted it back to R12 and gained about 8 degrees at the vent (will go to about 42 degrees now). I understand that systems designed for 134 (such as modern kits) work fine but they are made for 134. When I had 134 in my system I made adaptors to fill it so I could keep the R12 fittings (for appearance). Good luck, Don H.

[Michael L.]

Re: Question on R12 vs R134a for '69 A/C

Thanks Don. How did you make the adaptors?

[Mark E.]

Re: Question on R12 vs R134a for '69 A/C

I'm not am AC professional either, but agree with Don regarding oil and refrigerant. If you have R12 (last I checked, you can get it from China via eBay),, the system will run more efficiently.

[James W.]

Re: Question on R12 vs R134a for '69 A/C

Don what adapter did you put on your '65? Just curious since my '65 was converted to 134, but I'm going back to R12.

James

[Michael L.]

Re: Question on R12 vs R134a for '69 A/C

Thats what I am thinking Mark. Does anyone know what size the traditional R12 couplers are? If I can find that out I can order generic couplers so I can charge through R12 fittings. Is there a specific size of those R12 fittings?

[Tom L.]

Re: Question on R12 vs R134a for '69 A/C

Standard firrings are 1/4" flare on R12 systems. Going to share my opinion on R12 vs. 134a. IF the system is put together with the proper seals for PAG or POE oil AND the POA valve is re-calibrated for 134a (you WILL be dissapointed if this step is skipped) the system will work just fine. I converted a number of years ago and I'm very happy with the way it performs.

I've been in the commercial refrigeration buisness (Not auto so I'm not an expert on auto A/C) for 30+ years. Since the whole CFC thing became a problem the chemical companies have been doing a good job providing refrigerants that will keep all types of refrigeration systems running for years to come. But the replacements all have replaceemnts and those are also on the chopping block. 134a, R404 and R410 were supposed to be the refrigerants that were going to be the solution but they are on the way out. It's insane, I stock, and I only do side work now since I retired, and I have 10 different refrigerants, I probably should have more.

So the real reason that I changed was 12 was expensive and getting scarce and 134a only cost me about $3/lb at the time. the cost of refrigerants has gone insane over the last three yers. Now 134a costs me almost $20/lb when I by a 30lb cylinder so really there isn't much of a cost benefit any more. On top of that 134a is quietly being phased out which means it too may become scarce the way 12 has. But in reality if you want 12 it's out there you just have to pay.

So between costs and potential availability problems I'd say it's just a personal choice. Not will 134a work as well as 12.

So there's my 2 cents. Have fun!

[Michael L.]

Re: Question on R12 vs R134a for '69 A/C

Tom so how are the couplers different on R12 and R134a systems? if R12 are standard 1/4 flare, what are the R134a that make the two incompatible? What kind of quick release couplers could I order in order to get a new gauge set to work with R12 couplers?

[Tom L.]

Re: Question on R12 vs R134a for '69 A/C

The couplers were only installed on cars so mechanics would have a tougher time making the mistake of putting 12 in a 134a car or 134a in a 12 car. They are NOT necessary. Most adapters that are added to cars, like our vettes, just screw onto the 1/4 flare connection so that it becomes a quick connect. The adapters are NOT necessary, they're just a visual indicator for the shop mechanic. For example, ALL of my guage sets are 1/4 flare and I use them for all refrigerants. Except for R600 and R290 but that's another story alltogether.

[Michael L.]

Re: Question on R12 vs R134a for '69 A/C

OK thanks Tom. I just watched another youtube video and discovered that there aren't quick connect couplers on the R12 system. When servicing those you just screw the hoses directly to the ports. Wouldn't that result in a bunch of refrigerant leaking out when the hoses are screwed off?

[Michael L.]

Re: Question on R12 vs R134a for '69 A/C

Also, I have read about utilizing a temperature/pressure chart to help with proper charging of the R12 system. Can you explain to me how to use this chart? Is it as simple as looking up the ambient temperature when your working on a car and then charging the system on the low side to the associated pressure?

Mbsm_dot_pro_private_picture_Temperature-Pressure-chart-2.jpg

[Don H.]

Re: Question on R12 vs R134a for '69 A/C

I just went through my AC parts and do not have the adaptor anymore. What I did was use the original fittings on the car and standard R12 gauges to vacuum the system. Then to add 134 the adaptor connected the 134 can valve to the gauge set. I remember that you use less 134 (can't remember the exact %) in a R12 system.

[Tom L.]

Re: Question on R12 vs R134a for '69 A/C

Any time you put a guage on a port of any kind pressure fills the hose and guage. Typically minimal when tapping the low side but on the high side there is more loss. If you're concerned about that just tap the high side when you need to or do your checks, shut the car down, let the pressures equalize and then remove. There will likely be a spurt of oil with it so don't be surprised, not a big deal.

As far as the P/T chart, it's above your pay grade and these systems are not that simple since there are 2 low side ports that can mislead you. Not being mean but the best way to charge any system that has a specified quantity of refrigerant is to weigh it in.

[Michael L.]

[Jeffrey S.]

Re: Question on R12 vs R134a for '69 A/C

Mike,
Here is a source for adapters. I have bought from them many times.

https://www.es-refrigerants.com/products/w/id/57/t/adapters/

Hope this helps.
Jeff