Air Conditioning evaporator

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  • #83656

    I have found a very slow leak in the AC system of my 414A. It is in the evaporator that is located under the copilot’s seat. A new one is about $8,000 and that does not include any labor. I have a line on a used one about a year ago for $1,250 but I didn’t act and now it is gone. We seem to be unable to find another used unit and the only shop we found that might repair mine is not willing to commit to anything until they actually see the evaporator.

    Has anyone dealt with a similar problem? Any suggestions? Fortunately the leak is slow enough that I only need to recharge the system once a year…for $600. Still, I would like to fix it if I can find a reasonable cost.
    Thanks,
    Pete

    #95392
    rwelsh
    Participant

      Pete, what don’t you just buy 4 cans of Freeze 12 and put a can in when needed. It is quite simple. You can even buy the gauges and hoses from Harbor Freight very inexpensively. One can of Freeze 12 is 8 or 12 ounces depending on size. The whole system takes about 2.5 pounds if it is completely empty.
      You should be getting the pressurization manuals today.
      Dick

      #95399

      Dick,
      Do you know anyone that has done this? What fittings are necessary to get the the Freeze 12 from the can into the system?

      I got the manuals today…Thank you!
      Pete

      #95409
      rwelsh
      Participant

        Pete, I have used Freeze 12 in the 340 and the 310 for 10 years now. When you first buy Freeze 12, you need to purchase the hose and connector kit. The connector clamps on the can and an attached puncture pin opens the can to the hose which connects to the AC gauge and hose setup which connects to the fittings next to the evaps in the back or the fittings on the compressor. It is not recommended to use the compressor fittings as you need to run the right engine while filling the system to prevent overpressure.

        Freeze 12 appears to be about 80 percent methane and a few other gases according to the MSDS on Freeze 12. Google Freeze 12 and you will find tons of sellers for quite a range of prices, but it is all manufactured by the same company.

        #95412

        Dick,
        The evaporators in my plane are under the seats in the cockpit and require quite a bit of work to access. Do you think there are any other points of access other than the compressor?
        Pete

        #95419
        rwelsh
        Participant

          Pete, I forgot you had a 414, and I am not familiar with its inner workings.
          Dick

          #95443

          Pete,
          I have a 421, but the AC system is the same on the 414. The fill port is accessed from behind the right engine on the low pressure side of the compressor. There may or may not be a low pressure port accessible inside the plane. Do you know if your system is R12 or R134a? They also sell dye additives that might help you pinpoint the leak.

          Even R12 is not going to cost you $600 per year, I don’t have any direct experience with Freeze 12 but it seems to work well for Dick.

          A good A/C shop should be able to fix your evaporator – it will help if you can find the exact leak.

          Some other tips – you can buy a freon detector and help troubleshoot where the leak is. Much better than soap bubbles. Watch out for the clear inline sight window near the co-pilot evaporator. Mine had a leak between the metal and the glass, we ended up just capping it (since it is impossible to see anyway)

          #154018
          abarton1
          Participant

            Anyone know what the plug size for a defective sight glass is? Ours has a leak between the glass and aluminum. I think its a 9/16×18, but there are no specs for the part in the maintenance manual. Like everyone else, we will delete the useless sightglass and plug the port. A replacement sightglass used is over $300.

            Part no. M124FZ

            Considering this part:

            https://www.jegs.com/i/Aeroquip/023/FBM3724/10002/-1

            #154029
            rwelsh
            Participant

              I thought it was a 1/4″ pipe plug, but it has been a few years since I did it.
              Dick Welsh

              #154032
              mobarr1
              Participant
                quote RWELSH:

                Pete, what don’t you just buy 4 cans of Freeze 12 and put a can in when needed. It is quite simple. You can even buy the gauges and hoses from Harbor Freight very inexpensively. One can of Freeze 12 is 8 or 12 ounces depending on size. The whole system takes about 2.5 pounds if it is completely empty.
                You should be getting the pressurization manuals today.
                Dick

                Dick,

                Are you still having good results using Freeze 12? I have 2 airplane and a boat using R12 and have several pounds of it in stock.

                Mike

                #154037
                rwelsh
                Participant

                  This is the 8th year the Freeze 12 has been in the system. I have not had to put any in those 8 years, and I use it a lot as we live in the desert 8 months of the year.
                  Dick Welsh

                  #154046
                  mobarr1
                  Participant
                    quote RWELSH:

                    This is the 8th year the Freeze 12 has been in the system. I have not had to put any in those 8 years, and I use it a lot as we live in the desert 8 months of the year.
                    Dick Welsh

                    Thank you.

                    #154190
                    dsanov1
                    Participant

                      Pete,

                      There is a refill port in the cockpit of your 421C. Its on the lower right side of the co-pilot seat. If you slide the seat all the way forward (or take it out), you will see the refill ports. The forward port is the low side, and the aft port with the site glass is the high side. The simplest way is to simply attach an R12 hose from your freeze 12 to the low (forward) port. Then start the engine, turn the AC on high, and slowly open the valve to allow the freeze 12 can to get sucked into the system.

                      I do this once every summer when my AC starts to get warm, and it remains cold for the rest of the season. One can each year is a much better option than the costs associated with chasing down and repairing a small leak. I know someone who simply uses R-134a instead of freeze 12, but the oils are different, and that may create an eventual issue for the compressor.

                      Dave

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