Automotive Air Conditioning Information Forum

My car calls for 1.35 lbs. of r134a for a refill, what are some common methods of weighing this amount I have 12oz. cans. Thanks!

Techs who don't own a very costly Recover, Recycle, Recharge (RRR) machine typically use a highly accurate refrigerant scale, together with a quality manifold gauge set, like those available at www.ackits.com

It's more difficult weighing-in a charge using the small 12-ounce cans rather than using a 30-pound cylinder, but it can be done. The scale counts the number of ounces, or grams, of refrigerant flowing out of a container and into the system. Some scales do this automatically and stop at the desired amount, while others require the operator to watch the display and shut off the refrigerant flow manually after the desired amount has been reached.

In your case, after evacuating the system well, you'll need to charge 21.6 ounces or 612 grams, which will require two of the small cans, presuming that each can contains a true 12 ounces. Sometimes they don't. In addition, don't forget to purge the yellow hose of air at the manifold gauge set each time, and write down the amount you charged from the first can so that you can add the remainder.

I strongly advise against using one of those "miracles in a can" often found in big-box and auto parts stores that sometimes contain sealers and other additives, which can seriously compromise a system.

Look, I am a newbie here and to a/c systems but I used a very accurate scale which I happened to have on hand (used to measure certain insecticides) and which I bought off Amazon some time ago. I suppose it might be difficult (beyond scale's limitations) to place can in container of warm water while using this scale.

I used an electronic scale I bought on ebay for around $10 including shipping. I found the sticker, my location was by the strut tower in the engine bay. It describes the type of gas used and how much. Something i have always wonder if you weigh the can and can tap does that dilute the Oz weight of tetrafluoromethane that you are putting in the AC system? so most scales have a "TARE" function so for instance in food preparation if you want 20oz of cheese you would first put your empty container on the scale then tare the weight of the container which makes the scale read zero. Then you put your cheese in and it just shows the weight of the cheese. So I do that i put an empty can of 134A and a can tap and adapter....you all are using the adapters for the self seal cans right? i tried just using the can tap and the can leaked. Any way I tear the empty can+ can tap+ adapter + the yellow hose attached. Then when i use the full can it shows just the weight of the 134A in the can.
another milestone I sold all my R12 Dichlorofluoromethane to refrigerant finders . I remember the last day you could by R12. I believe it was 1987. I went to Hi Gear and bought 4 cases

My car calls for 1.35 lbs. of r134a for a refill, what are some common methods of weighing this amount I have 12oz. cans. Thanks

16 Oz's in 1 pound so that would be 16 + ( 16x .35) = 16+5.6 = 21.6 oz's which most systems have a + or - by some percentage so it's not exact.

0utThere wrote: ↑Tue Jun 07, 2022 5:17 pm So I do that i put an empty can of 134A and a can tap and adapter....you all are using the adapters for the self seal cans right?

I can't speak for others, but I don't use the small 12-ounce cans. What I do use is the 30-pound cylinders, which IMHO are easier to deal with on a refrigerant scale in that you can charge a system without having to change-out the small cans as you go, which has the potential for introducing errors.

0utThere wrote: ↑Tue Jun 07, 2022 5:17 pm Any way I tear the empty can+ can tap+ adapter + the yellow hose attached. Then when i use the full can it shows just the weight of the 134A in the can.

I don't think your method would work accurately although it probably would be close. What I would do (if I were to use a 12-ounce can) is put a full can on the scale, along with the tap, adapter (if used), and hose, "tare" or zero all of that, and proceed to charge. The scale would then tell you exactly how much refrigerant went into the system. Note that the 12-ounce cans often contain less than 12 ounces.

JohnHere wrote: ↑Sun Jul 04, 2021 11:13 am It's more difficult weighing-in a charge using the small 12-ounce cans rather than using a 30-pound cylinder, but it can be done.

In your case, after evacuating the system well, you'll need to charge 21.6 ounces or 612 grams, which will require two of the small cans, presuming that each can contains a true 12 ounces. Sometimes they don't. In addition, don't forget to purge the yellow hose of air at the manifold gauge set each time, and write down the amount you charged from the first can so that you can add the remainder.

I'm not a professional, but see above. Your system needs almost two cans, and you'll never really get 24.00 oz from 2 cans anyway. So 2 cans should be quite close.

Yes about purging the air out of the yellow hose, and NEVER use any sealer or refrigerant containing sealer. Adding some UV dye is fine, either by itself, or refrigeration oil containing the dye, or even pure R134a containing dye.

I agree. Use two 12 oz cans and call it a day.

tony1963: Just a friendly reminder that some of the topics on which you've commented are around a year or more old, like the one above. Chances are, the OP won't see them.

JohnHere wrote: ↑Sat Jul 08, 2023 11:38 am tony1963: Just a friendly reminder that some of the topics on which you've commented are around a year or more old, like the one above. Chances are, the OP won't see them.

I sure hope the OP is still not waiting to charge their system.