Based on symptoms and measurements, I have reason to suspect that my neighbour's car's AC system has too much refrigerant in it. Some of the refrigerant has to go.

To my knowledge, even if environmental regulations penalize the local automotive repair industry for venting refrigerant to the atmosphere it is poorly enforced, so if the neighbour takes it to an average repair shop they wouldn't hesitate to mash on the valve release.

Rather than act irresponsibly and release it to atmosphere, I would like to know if it is possible to use a spent refrigerant bottle (the disposable kind like in the picture below) to store the excess refrigerant so that I can take it to a specialist workshop that has the ability to recycle it at a later date.

The thing I'm not sure about is whether these bottles can come with a one-way/check valve that ensures they can only be emptied, not refilled.

Under Handling Precautions for HFC-134a Shipping Containers, I also found this:

  • Never refill disposable cylinders with anything. The shipment of refilled disposable cylinders is prohibited by DOT regulations.
  • Never refill returnable cylinders without DuPont consent. DOT regulations forbid transportation of returnable cylinders refilled without DuPont’s authorization.

There does appear to be some evidence that suggests these regulations are driven by product integrity concerns:

In some instances, says MOPIA, the refrigerant contained within the cylinder is not as labeled, particularly in the case of R134a and R22.

'One cylinder we analysed, which was supposed to contain virgin R134a, actually contained a mixture of R22, a hydrocarbon and R134a,' said Mark Miller.

Example R134a bottle

  • So, how were they filled in the first instance?
    – Solar Mike
    Commented May 29, 2018 at 7:51
  • Why not try - they are rated to store that stuff - if it goes in it goes in, if not the pressure relief on the rest of the system will cope - unless someone has removed / changed / interfered...
    – Solar Mike
    Commented May 29, 2018 at 7:53
  • I fully intend to try it when I have the opportunity to pass by a garage that has one up for adoption. Until then it would be nice to know if there is a red flag that would render this approach meaningless.
    – Zaid
    Commented May 29, 2018 at 8:19
  • So suggesting you inspect the one you don’t have is meaningless...
    – Solar Mike
    Commented May 29, 2018 at 8:35
  • @Zaid - I cannot see the image from work, but I'm assuming it is the typical R134a can which I'm used to here in the States. Commented May 29, 2018 at 10:48

2 Answers 2


tl dr: You can do it, but you probably won't be able to bleed very much off by this method.

NOTE: Please see edit at the bottom.

Most every can of DIY refrigerant I've ever seen (whether R12 or R134a) has a puncture top design (NOTE: AC Pro may be different, as it is an all-in-one). As you screw the adapter onto the top of it, there is a small tube which is cut on a bevel which punctures the top of the can, which then releases the refrigerant from the can and then is available to flow after you press the lever. There is no check valve at the top, but a thin piece of metal which contains the R134a until punctured. If the can were completely empty when you started, you could fill the can back up to whatever the maximum pressure of the AC system on the low side is at the time you are doing the bleed. This would allow you to bleed off some of the refrigerant.

The question then becomes, can you bleed off all you need to bleed off? Without a means of sucking it out of the AC system and pumping it into the can, the best you can achieve is the pressure in the system. And then because the DIY method has you putting refrigerant into the low side, that's the maximum pressure you could attain. IIRC, that's usually a maximum of around 45psi. I know the low side does spike when the compressor goes off, but as it goes back on, it will draw some of that pressure back out of the can as things equalize.

The other thing to think about is, if you want to use your DIY recharge device when you're done pulling what little R134a you can out of the system, you'll need to take it to the recycle shop before you can do so. You wouldn't want to use it in another car, as you run the risk of contaminating the system of the next vehicle you're working on.


After finally seeing exactly what you are trying to use to store the R134a, I don't see any reason why you wouldn't be able to. This type of bottle has the valve to shut off the flow (either in or out) of the bottle. Once you get out of the system what you need to pull, shut the valve and be done with it. With as large as the bottle is (originally I was thinking you were trying to use the smaller 12 or 16oz cans ... ), the only problem you'll need to worry about is pulling too much refrigerant out of the system. Anyway, yah, go for it. Looks like you are trying to be DIY and environmentally friendly at the same time.

  • I imagine that using the high-pressure port or even turning the AC off would create a sufficient pressure difference between the system and the bottle to siphon off the excess.
    – Zaid
    Commented May 29, 2018 at 13:57
  • @Zaid - I was talking for the basic DIY'er is not going to have a means to port off of the high side. That's what I was basing my answer towards. Yes, the high side is up over 200psi (IIRC) and would allow to siphon off more refrigerant. I don't think it's going to be that much of a difference in how much refrigerant you can siphon off, though. Commented May 29, 2018 at 14:24
  • Ah, I should have made it clear that I was planning on using a manifold gauge set like this
    – Zaid
    Commented May 29, 2018 at 14:25
  • @Zaid - Also, once you have what the can can hold (or the pressures equalize between the can and the AC system), you'd have to leave everything hooked up to the can as there would be no real way to seal it off, then you'd have to take it to the recycle center to have that bled off. If you don't get it done the first time, you'd have to make additional trips. Commented May 29, 2018 at 15:18
  • CA refrigerant cans are all self-sealing and would probably be really good for this. Also, you could simply turn off the A/C system and let it equalize at ~100 psi or whatever, and therefore you could re-pressurize the can to this pressure. Commented Dec 16, 2020 at 21:49

This 30 LB refrigerant tank has one way valve. You may only discharge it, not refill it. You may cut out very top of rim of valve just where it curves with dremel. It will give you ability to unscrew stem out of valve. Then you will need to remove spring and metal ball. Then screw stem back to valve and now you may refill it. MAKE SURE THERE IS NO PRESSURE LEFT before you do it!!! But actually why bother? You will have to went out very little of refrigerant out of car AC. Not a big deal considering that million of cans of this same refrigerant(R134A) vents out by people at home every day. How? You will be surprised that "compressed air" sold in Office Depot store to clean computer keyboards is actually R134A. Read label :))

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