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Thread: A/C Refrigerant Capacity?

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    Senior Member Alphamacaroon's Avatar
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    A/C Refrigerant Capacity?

    Getting ready to charge the FFR supplied A/C kit in my Type 65 Coupe.

    Might be over thinking it, but is there any other guidance as to how much R134A to add other than 2 x 12oz cans of R134a and 1 x 12oz can of R134A with oil? Or is a full 36oz about the right amount?

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    Senior Member sethmark's Avatar
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    Usually it’s 28oz. Make sure you pull vacuum for a good 30 minutes before charging.
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    Senior Member Alphamacaroon's Avatar
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    Excellent. So I assume I should empty the R134A with oil, then weigh out 16 more oz from the two remaining bottles?

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    Senior Member sethmark's Avatar
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    No! Leave the oil in.....
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    make sure that you evac the system before you charge it. leak check it first then charge to pressure not weight for the first time. best to take it to a shop to properly charge it I could charge it for you but your about 4hrs away in olympia

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    Senior Member Alphamacaroon's Avatar
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    Quote Originally Posted by sethmark View Post
    No! Leave the oil in.....
    Right, I meant fully empty the first charge R134 oil can into the AC system 😀

    acmikee I’ve fully evacuated (45 mins on vacuum). What pressure do you recommend?

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    Senior Member edwardb's Avatar
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    Mine is installed but not charged yet. So offer this FWIW. The Factory Five instructions say (2) 12oz 134a refrigerant cans, (1) 12oz 1st charge (has oil in it). I called and asked about this since I noticed while installing that the compressor did have some oil in it, and was concerned adding the refrigerant with oil would result in too much. They said no and to follow the instructions. So I believe your first question is yes. Use that amount. I'm seriously considering buying the necessary equipment to do it myself. Would pay for itself after the first charge, especially if I had a leak or whatever. Plus keep hands that I don't know from messing with my car.
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    Senior Member Alphamacaroon's Avatar
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    Ended up doing it myself last night and I think it went pretty well. I purchased the manifold set and vacuum pump from Harbor freight and they worked pretty well. Although make sure you check the manifold itself for leaks first— thought I had a system leak, but it ended up being a faulty seal where the hose connects to the manifold so I had to exchange it for another one at HF.

    I charged mine pretty early in the build process, but I wanted to make sure everything worked before I started making wiring and hose connections more difficult to access. The good news is that that compressor kicked over when the refrigerant pressure got sufficiently high, and cycled on and off with the t-stat, so I think I'm in business.

    The only part that I’m not sure about is that it seemed to take a LONG time for the refrigerant to get pulled into the system. I’m not sure if this is normal, but I think it might also be due to the fact that it was pretty cold in my garage and the r134 can and low pressure shrader valve connection started icing over. Maybe the cold temps caused the connection to ice up? Maybe I was introducing the r134 too fast? I was eventually able to get all of the first charge and an additional one and a half cans of R134 in. I’ll check it again in the summer.

    Still not sure what proper high and low pressure should read.
    Last edited by Alphamacaroon; 12-07-2019 at 03:26 PM.

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    Senior Member Alphamacaroon's Avatar
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    Follow-up on pressures. Here's what I'm seeing:

    I turn on the AC, the compressor starts, and the low-side appears to start around 25 PSI and the high-side starts at about 150 (might have been 125, can't quire remember) PSI. The temperature in my garage is about 40F.

    But as the compressor runs, the high-side quickly climbs up to around 250 PSI (20-30 seconds) at which point the radiator fan turns on. When the fan turns on, the high-side pressure drops pretty drastically again until it reaches around 125-150 PSI again, the fan stops, and then the whole process repeats itself.

    Last night when the engine was running for a while and the fan was pretty much constantly on (as the crate Coyote tends to do), the high-side never really got above 50-75 PSI.

    Is any of this normal? The pressure seems to be highly dependent on whether or not the radiator fan is cooling the condenser— which I guess makes sense to some extent, but the pressure swings seem pretty radical.

    Should I be measuring for proper pressure when the fan is running or not running? If the answer is "when it's running", then maybe I'm slightly under-charged?
    Last edited by Alphamacaroon; 12-07-2019 at 03:30 PM.
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    Senior Member edwardb's Avatar
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    I don't pretend to know much about this. Will learn more when I try to do the same thing. Three comments though. (1) Tons of videos in YouTube on how to do this, what you should see, etc. (2) Not sure you'll see "normal" pressure readings with a 40 degree ambient temp in your workspace. (3) Are you getting a temperature drop through the vents in the cockpit? Measuring that is one of the checks, although (again) not sure how it's going to work in that cold temp.
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    Senior Member Alphamacaroon's Avatar
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    Yeah, you’re probably right about the ambient temp. I didn’t have a thermometer handy, but the fact that the low pressure inlet was icing up on the outside meant that it was definitely getting cold, and the air coming out definitely felt cooler. I’ll wait until the summer to check again.

    This video was the one I followed (which felt like one of the better ones of all I looked at): https://youtu.be/Pdq8JAlct6s . Not much info on pressures though. One thing that tripped me up was that he said you have to tighten the valve to puncture the can, then loosen it to let refrigerant out. But the newer cans appear to be self-resealing, so you actually screw the valve in all the way, and keep it there to let refrigerant out.

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    sounds like your under charged but its hard to charge with it being so cold outside or in your shop whats your supply air temp the 50-75 on the high side is way to low

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    25th Anniversary #9772 toadster's Avatar
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    pulling vacuum on my system but doesn't hold vacuum, loses vacuum in less than a minute - best way to test for leaks with an empty system?
    Todd
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    R-134a (and other refrigerants) sniffers can be had for relatively cheap.

    Given how cheap R-134a is, I'd throw a couple of cans in the system without running the pump and see if you can find the leak with a sniffer. If you need to bump the pressure, add some nitrogen.

    My money is on a hose-end connection, sometimes the o-ring gets twisted up weird when you set it.
    Rob Windsor

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    25th Anniversary #9772 toadster's Avatar
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    Quote Originally Posted by Windsor View Post
    R-134a (and other refrigerants) sniffers can be had for relatively cheap.

    Given how cheap R-134a is, I'd throw a couple of cans in the system without running the pump and see if you can find the leak with a sniffer. If you need to bump the pressure, add some nitrogen.

    My money is on a hose-end connection, sometimes the o-ring gets twisted up weird when you set it.
    problem is I can't seem to get any R134a into the system, I have these from Autozone https://www.autozone.com/a-c-chargin...2oz/244738_0_0 which I think need a vacuum to pull the refrigerant

    should I get a pressurized can to force some into the system?
    https://www.autozone.com/a-c-chargin...archText=r134a

    I was thinking it could get an adapter - I believe air hose connectors are 1/2" NPT to a 7/16-20 thread for the R134a hose then pressurize the system and listen for leaks...

    can't seem to find an adapter though
    Last edited by toadster; 12-05-2023 at 01:24 AM.
    Todd
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    Senior Member Kbl7td's Avatar
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    You have a pretty big leak then, before doing all that go back and make sure all the threaded connections are super tight, make sure no o-rings are broken. Pick up some Nylog blue. I’m assuming your did your own crimps, they need to be tight tight, as in you need to go fully seated on the crimping tool. Make sure you’re actually using the manifold correctly as well and that you’re shutting off both valves on the manifold while the vacuum is running. The thing should hold overnight+++ with a vacuum.

    Also for those who charge in the future, the can will get cold as it goes into the system. Microwave some water and get it up to 100 something degrees, place the can in the water bath to help release the refrigerant and keep it from getting too cold.

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    Senior Member edwardb's Avatar
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    Kbl7td pretty much said everything I was going to say. Go back over everything. Tighten hard. No big deal IMO to take hoses back off and check the o-rings and re-tighten. Those green o-rings are cheap. I bought a selection of sizes on Amazon for not much. If the o-ring doesn't look perfect, replace it. I too used the Nylog blue. I'm not an expert at all. Have done two installs making my own crimps with the Mastercool crimper. The Coupe was good from the start. The truck I had to redo one of the connections including new fittings and hose because I messed up the crimps. It was a slow leak that showed up after charging. Found with UV dye. But that wouldn't apply to you. The R134 cans are under pressure. Those DIY charge cans are the same. Just with fittings, gauge, etc. I wouldn't put R134 into a known leaking system. Especially the gross leak you're describing. It's illegal to discharge a system into the atmosphere. Even though (I know...) leaking systems are doing the same thing just slower. But still something to avoid.
    Last edited by edwardb; 12-05-2023 at 07:47 AM.
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  22. #18
    25th Anniversary #9772 toadster's Avatar
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    Quote Originally Posted by Kbl7td View Post
    You have a pretty big leak then, before doing all that go back and make sure all the threaded connections are super tight, make sure no o-rings are broken. Pick up some Nylog blue. I’m assuming your did your own crimps, they need to be tight tight, as in you need to go fully seated on the crimping tool. Make sure you’re actually using the manifold correctly as well and that you’re shutting off both valves on the manifold while the vacuum is running. The thing should hold overnight+++ with a vacuum.

    Also for those who charge in the future, the can will get cold as it goes into the system. Microwave some water and get it up to 100 something degrees, place the can in the water bath to help release the refrigerant and keep it from getting too cold.
    Quote Originally Posted by edwardb View Post
    Kbl7td pretty much said everything I was going to say. Go back over everything. Tighten hard. No big deal IMO to take hoses back off and check the o-rings and re-tighten. Those green o-rings are cheap. I bought a selection of sizes on Amazon for not much. If the o-ring doesn't look perfect, replace it. I too used the Nylog blue. I'm not an expert at all. Have done two installs making my own crimps with the Mastercool crimper. The Coupe was good from the start. The truck I had to redo one of the connections including new fittings and hose because I messed up the crimps. It was a slow leak that showed up after charging. Found with UV dye. But that wouldn't apply to you. The R134 cans are under pressure. Those DIY charge cans are the same. Just with fittings, gauge, etc. I wouldn't put R134 into a known leaking system. Especially the gross leak you're describing. It's illegal to discharge a system into the atmosphere. Even though (I know...) leaking systems are doing the same thing just slower. But still something to avoid.
    thanks guys (as always) - now that the engine is running properly I can tackle this now

    I ordered these parts to get the next phase rolling:

    1/4-Inch Female Flare by 1/4-Inch Male Pipe Thread Brass Adapter <- to pressurize with air to test for leaks, not ideal as it will induce air/moisture, but will have to re-vacuum the system

    Air Conditioning Compressor Seals O-Rings 270 pieces is a lot, but at least available

    RT201B Nylog Gasket/Thread Sealant - for some reason I don't remember reading about this before, I have used the provided sealant but trust you guys on this!


    Thanks!!
    Todd
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    Another thought is to charge it with nitrogen (adapters needed) and use the old-school soapy water bubble test on the joints.
    Rob Windsor

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    25th Anniversary #9772 toadster's Avatar
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    Quote Originally Posted by Windsor View Post
    Another thought is to charge it with nitrogen (adapters needed) and use the old-school soapy water bubble test on the joints.
    yes, the nitro method would be preferred, but will try just an air compressor first, not idea as it induces air/moisture, but once remedied will have to vacuum anyways to remove it all
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    DO NOT USE YOUR AIR COMPRESSOR TO LEAK CHECK this will introduce moisture into your system

  27. #22
    25th Anniversary #9772 toadster's Avatar
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    Quote Originally Posted by acmikee View Post
    DO NOT USE YOUR AIR COMPRESSOR TO LEAK CHECK this will introduce moisture into your system
    I understand that, but won't the vacuum remove the moisture again if I run it for a few hours?
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  28. #23
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    I have a small nitrogen bottle if you need, have no idea on what adapter you may need though
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  29. #24
    25th Anniversary #9772 toadster's Avatar
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    Quote Originally Posted by Just puttering View Post
    I have a small nitrogen bottle if you need, have no idea on what adapter you may need though
    depends on what the bottle outlet is to be honest , at this rate of gathering $15-20 parts for one time use, it may be simpler to trailer it to an A/C expert
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  30. #25
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    the vacuum pump probably wont remove all of the moisture. you would have to change the drier after running it. also never use oxygen

  31. #26
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    Some do's and don'ts when A/C charging. 1. Use safety glasses, freon to the eyeball immediately freezes the cornea and blindness will result. 2. Always ad freon gas, no liquid, into the suction side of the compressor. Unless you have a professional A/C machine which most of us don't have. Liquid freon in the suction side will slug and crack the reed valves in the compressor. Then the compressor quits pumping. If you have a hard time getting it to flow into the system because ambient temps are low place the can into warm/ hot water to force the freon out of the can. Always have the can facing up to release as gas. High side pressures are hard to get up to 250 if the ambient temps are 60 or below. As a general rule low side is around 25 psi and high side is around 250-300 and this always depends on ambient temps usually around 80 degrees. A/C driers will only hold so much moisture. Try to keep them closed up as long as possible before connecting them to the system. And yes, when you pull a vacuum ti will remove most of the moisture but not all. Vacuum for 30 minutes minimum. In general, the fan should be running any time the compressor is running. With out the fan the high side pressures will build rapidly because of no heat exchange in the condensor. I don't know if the systems FFR sell uses a trinary switch on the high side to operate the fan or not. Hope some of this helps
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  32. #27
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    Also when checking for leaks, if its big it's obvious to find. But if it's not visible, Spray soap bubbles on all the hoses and fittings will find leaks down to about four ounces a year. anything smaller than that a sniffer or dye will be required.
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  33. #28
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    I found a nice little 134 pressures chart online which might be helpful.134pressure.PNG
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  34. #29
    25th Anniversary #9772 toadster's Avatar
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    I did a full refit/lube and tightened everything up - much slower leak now, but still leaking - i had to modify the angle on a few of the fittings which may have damaged them
    trailering it to a local shop that does custom a/c setups to have them eyeball things...
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  35. #30
    25th Anniversary #9772 toadster's Avatar
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    shop found that my adapter into the compressor was x-threaded which was the leak point

    ordered two new fittings to replace, will have to wait and rebuid that endpoint, all other connections were good though!
    Todd
    25th Anniversary MkIV | #20 of 25 | Build #9772
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  37. #31
    25th Anniversary #9772 toadster's Avatar
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    2 12 oz cans - not totally empty, and about 6 oz of R134a - all good now!!

    Todd
    25th Anniversary MkIV | #20 of 25 | Build #9772
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