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Thread: A/C Recharge for R12

  1. #31
    LS1 DMC Nicholas R's Avatar
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    You should really spend an hour or so watching A/C recharging videos on youtube. You need to understand what you're looking at, and the differences when the engine is running vs. not running, the compressor cycling vs. not cycling, etc., as well as what you should expect from the gauges. There's nothing overly specific to the DeLorean that say you can only get your information from this forum. It's good to ask specifics here, but overall AC theory (which you need to learn) is consistent across all cars.

    The concern you see expressed in this thread is that you will damage something, or worse, hurt yourself. It's not personal. There are extreme pressures at play here. Simply attaching a can of refrigerant to the wrong side of the compressor could cause it to explode in your hand. On a car converted to R134 this is much less of a concern because a low pressure side charging hose wont fit on a high pressure side fitting. However, being that your car is still R12 with the same fittings on both the high and low sides, this is a very real possibility if you don't know what you're doing.

    Similarly, overcharging the system can damage the compressor due to pressure extremes. Charging too fast can damage the compressor, as the liquid can enter the cylinders instead of a gas, and the liquid can also wash out the compressor lubricant. Not having enough lubricant in the system can damage the compressor.

    There are times when you can jump into a car project with no knowledge and learn as you go. This may be one of those cases, but only provided that you understand the risks associated and have done your homework. In the end, no one on this forum is going to take responsibility if you hurt yourself or the car. Only you can be responsible for yours and the car's well being.
    Last edited by Nicholas R; 07-16-2018 at 10:14 AM.

  2. #32
    Administrator Ron's Avatar
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    Quote Originally Posted by Felix_29 View Post
    Well it is obvious you guys do know more than I do about this. You guys obviously learned this a/c stuff somehow yourselves. How would you feel if someone said to you "Don't do this job yourself" or "take it an a/c shop. seriously". I'm not sure why you feel i'm not capable of learning what you know... I won't learn anything if I keep taking the car into a shop every time it needs something. I'm trying to be learn more about my car and be cautious at the same time. I think i'm doing the right thing by taking it slow and asking questions. I'm not totally green to this. I only lack experience. I thought that was the point of this forum. For owners to help owners. I do appreciate the help I have received on this thread.
    What I think you are missing is that, when the compressor is not running, the pressure depends on the refrigerant's temperature, NOT how much refrigerant there is in the system, as long as there is a minimum amount present; e.g. When allowed to sit and settle to the ambient temperature, one can in the system would show the same pressure as 3 cans would. So, WRT amount, the only thing that the 58psi you read tells you is that there is some there. WRT pressure, it tells you that there is enough for the low pressure switch to send power to the compressor clutch. So, when you turn on the AC, the clutch should be engaging (even if very briefly). If not, the clutch's coil and/or electrical control has a problem...

    OK- Since you said, "I don't understand why my ac is not blowing very cold. The AC belt is turning when the car is on.", I assume the clutch is engaging, else it would not be cold at all. The poor output temps can be caused by anything from too low/high refrigerant charge to vent control. The charge is a good bet, but you would need a set of gauges to safely continue at this point AND get it right, as others have said. If you make a mistake and put more in it, due to the characteristics of refrigerants mentioned etc, it may work fine until a hot day (or future problem) comes along and the resulting overcharge damages something...or someone.

    ...Check out
    the link the Resources Section HERE then get your hands on a set of gauges, and hang in there!

  3. #33
    Senior Member NckT's Avatar
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    Always wear personal protective equipment (PPE) when dealing with refrigerant. Full safety eye goggles that seal around the face is a must at the very least. Refrigerant coming out under pressure can also freeze skin, as well as asphyxiation....

    I'll assume you'll read up on working safely with refrigerant and not take this lightly. You only get one set of eyes....

    Good luck, be safe, be seeing you
    Last edited by NckT; 07-16-2018 at 02:45 PM.
    RIP Rob van de Veer Top bloke

    I say Sir, I must be mad, one loves fixing K-Jet !

    Make sure there's plenty in the tank for the weekend chaps....

  4. #34
    Join Date:  Jul 2011

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    So I hooked up the regulator to the system. Turned the car on. Set the A/C to max it can go with highest fan speed. The regulator would drop into the blue around 20PSI everytime the A/C clutch would spin. And when it stopped it would go back up to about 60PSI. This just happend over and over again like that until I stopped the engine. My car's A/C Clutch always starts and stops constantly like every 5 seconds. Is that normal? I have included a picture of the kit I bought. Only difference is I don't have the stop leak can.

    AC Recharge.jpg

  5. #35
    Administrator Ron's Avatar
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    That says the system is probably low. But, again, you can not tell how much nor when there is enough with the gauge you have.
    You need to take it to a shop and have the system checked to confirm then evacuated and recharged with the spec amount, or, use the method I mentioned above, in which case you need these:


  6. #36
    Young Padawan With The DeLorean kings1527's Avatar
    Join Date:  Jun 2012

    Location:  Oak Park, CA

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    So.....AC work. I'm a firm believer that if you're the kind of person that can pick up a book and/or look at videos on YouTube, then you can teach yourself how to do this. And let's be honest: ever take a good look at the people who do this kind of work for a living in a shop? Do they give off a cardiologist or astrophysicist vibe to you? No? Then you can do it, too.

    The DeLorean utilizes an cycling clutch orifice tube (CCOT) based system which was popular for the time period, specifically in GM cars (and then GM bought Harrison Radiator, who had designed the heating/AC system in the DeLorean). Why's that important? Because the guts of the system are identical between GM cars of that time and the DeLorean. That being said, this book is outstanding for our cars:

    Hopefully that above link works. Once you understand what all of the major components do (orifice tube, evaporator, condenser, accumulator, high side/low side lines, compressor), then start understanding the process that everyone's referring to. And there's a lot to be said for process, such as removing moisture from the unit and why it's important to use a new accumulator every time you open the system. This guy does a great job of showing you the process of filling:

    A few points from above postings:
    1) R12 is not hard to find and cost seems to have come down some over the years, probably because demand has decreased once cars that use R12 are becoming fewer. If you have an R12 system, consider keeping it R12. It doesn't take a lot to maintain things once you get it all dialed in. I last refilled my system with R12 over 4 years ago and aside from my original high pressure cutout switch going out a couple of weeks ago, it's been flawless. And cold.

    2) Be VERY careful using anything that has some type of "leak stop" in it. A total mess on many levels, potentially.

    3) Again, this is a VERY common AC system. This wasn't something that was so unique or indigenous to the DeLorean. Overall, the theory of AC is very simple once you learn it, the components are very simple to understand as far as their roles are concerned, and having the right equipment (such as manifold gauges and an AC vacuum) are doing things right. Also, in terms of being brand new to AC work, it's MUCH easier to start off with a completely empty system and a new accumulator and fill it from there based on weight rather than diagnose the pressure readings. That's provided you are leak-free and the system can hold a vacuum.

    You've got some time to put into this but the info's out there and people here will help you. But getting a solid, base-level knowledge is the first step.

    Alex Abdalla

    Late 1981, Grey 5-speed, 63k miles. Built 11/11/81

    A stock-look with modern, reliable technology.

    A full restoration with step-by-step "what I did" is in progress at

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