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  • Building a custom system

    I am building a very custom old Porsche 914 which is a mid engine vehicle. The only ac systems commercially available are under dash which wont work as they hit my knees and I just don't like the look. I have checked with every aftermarket ac company and no one has anything close to fitting my space in a non under dash configuration. I am building a custom evaporator box so that the system can take advantage of the existing vents and I will be adding more.
    I have the design all worked out but not having a lot of AC experience I have a few topics that I would be grateful for some information on.
    I have been able to locate evaporators that would fit my needs from existing vehicles but there are a variety of fitting/connector types. I can not locate the names of fittings that are anything other than the good old screw on types. Are there adapters that go from these single and double hole blocks to screw type fittings or available as fittings to crimp onto a hose? I have spent hours searching but I really don't know the proper question for Google so it gets me to the information. So first can I go from the bolt together fittings to the screw types or can I purchase the raw singe and double hole bolt together fittings to place on the hose?
    Second question, the floor of the car is currently off of the car giving me access to the inside of the main tunnel that runs through the cabin. There is room in there to run hard lines from the compressor to close to the evaporator, which I can run a soft line to (again bringing up the question of fittings) Is this even a good idea? This route removes the necessity to run soft lines under the outside rocker panels and then cut holes from the fender well to the compartment that the evaporator will be in. Running in the tunnel eliminates a possible water intrusion point and is a much more direct route. Due to what I assume to be fairly chilly temps in the lines I am concerned about condensation on the hard lines and having no real ability to drain if that is even a concern. Would insulating the hard lines prevent condensation?
    So first is the fittings issue, and second, would it be wise to run hard lines in the tunnel?
    Thanks for any help
    DJ

  • #2

    I would vote for hard lines in the tunnel for protection. If you use flare fittings it will make the hard lines easy to fab. Insulate if possible. Try not to have too many low spots where oil can pool.
    I know of no adaptors that are commercially made from "block fittings" (bolt type) to O ring or flare. If you can get a block fitting with a little aluminum line attached, you can cut and flare the hard line.
    I would suggest finding who supplies the automotive A/C shops and get their catalog. You could also ask at your local truck refrigeration shop (ThermoKing, or Carrier). MEI used to put out a fairly good catalog that you could look thru for fittings.
    Be aware that you need more than an evaporator, you need a matching Tx valve or orifice tube ahead of the evaporator.
    There are adaptors to convert O ring to Flare.
    There is a lot to consider when makeing a custom system, not the least of which is how much refrigerant to put in? Having made my own, I can tell you that there are no simple formula to know how much to use. I've looked and asked and always get the same answer " I don't know" so you will have a lot of trial and error before you get it right. Tx valve systems are far more forgiving of amount than orifice tube systems are. Over sizing the condenser a little bit is better than undersizing. Tx valve should be close to the systems size (1,1.5 or2 ton) the evaporator capacity will likely be the determining value.
    Are you planning on using a "remote" condenser with its own electric fan(s)?
    If using an orifice tube system don't place the accumulator far away from the evaporator or you might find the evaporator temp varies too much as the system cycles.
    Are you planning to place the evaporator in the back and use the heater duct work? if so you will have to insulate the ducts or you will loose all your cooling to heat absorption.
    You are taking on quite a project, keep us informed on how its going and we will try and help all we can from this end of a keyboard.

    Comment


    • #3
      Originally posted by Cornbinder89 View Post
      I would vote for hard lines in the tunnel for protection. If you use flare fittings it will make the hard lines easy to fab. Insulate if possible. Try not to have too many low spots where oil can pool.
      I know of no adaptors that are commercially made from "block fittings" (bolt type) to O ring or flare. If you can get a block fitting with a little aluminum line attached, you can cut and flare the hard line.
      I would suggest finding who supplies the automotive A/C shops and get their catalog. You could also ask at your local truck refrigeration shop (ThermoKing, or Carrier). MEI used to put out a fairly good catalog that you could look thru for fittings.
      Be aware that you need more than an evaporator, you need a matching Tx valve or orifice tube ahead of the evaporator.
      There are adaptors to convert O ring to Flare.
      There is a lot to consider when makeing a custom system, not the least of which is how much refrigerant to put in? Having made my own, I can tell you that there are no simple formula to know how much to use. I've looked and asked and always get the same answer " I don't know" so you will have a lot of trial and error before you get it right. Tx valve systems are far more forgiving of amount than orifice tube systems are. Over sizing the condenser a little bit is better than undersizing. Tx valve should be close to the systems size (1,1.5 or2 ton) the evaporator capacity will likely be the determining value.
      Are you planning on using a "remote" condenser with its own electric fan(s)?
      If using an orifice tube system don't place the accumulator far away from the evaporator or you might find the evaporator temp varies too much as the system cycles.
      Are you planning to place the evaporator in the back and use the heater duct work? if so you will have to insulate the ducts or you will loose all your cooling to heat absorption.
      You are taking on quite a project, keep us informed on how its going and we will try and help all we can from this end of a keyboard.
      Thanks for the information.
      I have a ton of room in the rear quarters in front of the wheels so the condenser will go there with the fans. Should be huge airflow at the inlet I am forming into the wide body.
      The evaporator with the valve is going into the area of the stock air distribution box just in front of the cabin where I will form a new evaporator box. I can then drop the hard lines right down into the tunnel and back to the motor compartment. I will be using a 280cfm SPAL 3speed cage fan mounted in the cabin, a whopping 44 sq ft, which will feed directly into the bottom of the box. Is there any preferred location for the dryer? Compressor will be a Sanden 505 or 508 model.
      So now I will start researching how to make the hard lines with fittings and then the short hoses.
      Thanks again.

      Comment


      • #4
        ? Placenet of everything in these is all different of course. A/C was never a concentration when designed new for OE use. My question is room or not for condenser in front of a rear wheel even fans or not has to have real outside air blowing nicely thru it or it isn't going to work at all. If exposed to tire some debris will wreck it in no time. Re-think that location most mid or rear engine things still put the condenser all the way up front and ran the lines which will be a challenge.

        I plead I've never seen one with A/C at all so can't help much. Last was a VW Vanagon (VW Bus if you will) ran everything to the front all that way. Receiver was underside of the vehicle and both ports just BTW was an OE set up, air cooled engine now all a long time ago,
        Tom
        MetroWest, Boston

        Comment


        • #5
          Be patient - http://www.gilmore-enterprises.net/912___914

          Comment


          • #6
            Gilmore does not have what I need. The condenser in the rear quarters will receive massive amounts of air while moving and there will be inner fender panels that will keep all debris away from the condenser. Many mid engine cars run the radiators in this location and the inlets I am forming are large and in a fairly high pressure zone. I mainly need to learn fittings. I was looking at compressor fittings and wondering if it could be possible to machine them to be female instead of male which would give me basically an adapter.

            Comment


            • #7
              Of course, if you have machine tools and ability gives you lots of options. Sanden makes many kinds of compressor heads with different connection options. GM pad type has lots of options as does O ring or flare. Good Luck.

              Comment

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