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New R12 AC system in Dodge D150 blowing relief valve - lack of condenser airflow?

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  • #61
    Recovery machines do not "suck" the oil out of the compressor sump or the receiver. They will remove any oil in suspension with the refrigerant. So the refrigerant isn't "dry" but does contain some oil and the same should be returned to the system when recharged. The fancy machines separate the oil from the refrigerant so you can know how much to put back.
    More or less a moot point if you are just pumping it out and then right back in once the repair is done.

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    • #62
      Originally posted by Tom Greenleaf View Post
      Just don't compare this to a Civic please with a sideways engine - no comparison.
      Any equipment to "recover" refrigerant should be separating out anything but good refrigerant to put back later. Super high end ones will just do the whole job punch in what you want it to do and quit telling why it couldn't if so. Mega buck machines none already said here or somewhere for R-12 exist too costly to service and keep for one vehicle a year if that!

      For a container a used any refrigerant can just momentarily ignore it says don't refill them marked all over them start with anything you use in a full vacuum and lock it there. Learn how to vacuum out your own gauges and hoses too at worst should only have the slightest possible spit of air in moving hoses around and only maybe some lock right at the ends. Too many types of stuff you need to know what you are using not all the rest of every type.

      The airflow was the top suspect you can just remove the fan clutch carefully and new bolts hold that pulley on. Now no double fanning in front of each other seems strange but may leave radiator and condenser in a slight vacuum spot despite it seems right.

      Now into "aero-dynamics" only know enough to not do it. Why wouldn't a helicopter use two smaller blades on top of each other? It doesn't' work is why.

      Remember with air or a vapor it's going from higher pressure to lower pressure limited to density of the air it has available. All that and what has been said is use of water takes all need for airflow OUT of the picture.

      Eh - this is going to get all drawn out. Did a lot of A/C (not by choice) for yachts! No fans for condensers ever they use heat exchangers like small to larger scuba type things with just the tubes soaked in constant new water the boat is in some small do unreal BTU exchange of heat including cooling exhaust cool enough you can touch it anywhere! That's serious heat exchange!
      Helicopters don't commonly use coaxial rotors for a variety of reasons but "doesn't work" is not one of them. Not only do coaxial rotor helicopters actually exist, but they have quite a few advantages at that - greatly improved stability, no need for a tail rotor, etc. They are far more common than you might think. I'm sure you've also noticed that many drones and little RC helicopters and hobbyist helicopters employ dual rotors. It effectively comes down to a battle of trade-offs. With helicopters, the trade-off is between stability (coaxial) and maneuverability (single overhead rotor plus a tail rotor). Most applicable to our discussion though - in terms of pure force/lift, coaxial rotor design is actually more efficient and produces greater lift with less power than a single rotor.

      Anyway, we will just have to agree to disagree on this fan setup deal. I have no doubt in my mind that the electric fans are just helping condenser ability rather than inhibiting it and that the problem is something OTHER than airflow across the condenser. Of course that still doesn't leave me any better off because I still have this problem of poor cooling and high pressure on the high side.

      All that said - I wonder if at this point it would be almost be worth it to just give up with the system as-is and install a big universal parallel condenser in front to convert to R134?
      Last edited by james89dx; 07-20-2018, 04:40 PM.

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      • #63
        OK - bad analogy. It's not "exchanging" heat is clearly the issue. From just that bring up the list of how could that happen and I'd like to see this come into normal ranges with water the forget fans totally for a test if already posted and it worked properly let's work on that.

        There's another but would require a warm to hot engine is "radiant" heat can go "upwind" in certain situations meaning radiator is so hot for the engine it's infecting the condenser. Never a problem I've run into was brought up by Nacho is his user name and here but doubt anyone is going to read this much already about it.

        High pressures noted means the heat is there so where is it going wrong if air, air density and proper flow both outside air and refrigerant can flow properly new or not there's only so many things that can go wrong not all are super common or make sense or don't yet to me?
        Tom
        MetroWest, Boston

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        • #64
          Originally posted by Tom Greenleaf View Post
          OK - bad analogy. It's not "exchanging" heat is clearly the issue. From just that bring up the list of how could that happen and I'd like to see this come into normal ranges with water the forget fans totally for a test if already posted and it worked properly let's work on that.

          There's another but would require a warm to hot engine is "radiant" heat can go "upwind" in certain situations meaning radiator is so hot for the engine it's infecting the condenser. Never a problem I've run into was brought up by Nacho is his user name and here but doubt anyone is going to read this much already about it.

          High pressures noted means the heat is there so where is it going wrong if air, air density and proper flow both outside air and refrigerant can flow properly new or not there's only so many things that can go wrong not all are super common or make sense or don't yet to me?
          I have also been posting on the Dodge forum so perhaps I forgot to mention it here, but one of the very first things I did was water on the condenser. That's what made me try the fans in the first place.

          I'll play around with it tonight and add some water to the condenser and get more pressure readings. Am I understanding that's what you'd like to see at this point? Pressure readings and vent performance with water across the condenser as the system is running?

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          • #65
            With water mist on the condenser you should see high side pressures near ambient temp, use the chart I linked to several pages ago, low 100's for high side, low side should be around 30 ish, with vent temp in the 40's.
            No reason you can't install a big parallel flow and keep R 12 if that is what you want to run, there more efficient but don't care what the gas is that is passing thru them.
            Last edited by Cornbinder89; 07-20-2018, 06:33 PM.

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