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Flushing an Automotive AC System

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  • #21
    UPDATE: 1 year 3 months..... (After flush with alternate flushing solutions)

    Still going strong.

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    • #22
      Good to hear!


      • #23
        With complete sincerity and honesty, it is still working very well. I did add a little freon about 6 months ago I think but that was only because it seemed that originally I used the bare minimum. As of today, the air coming out the vents is nearly factory cold.

        I did not change the condenser, only the evaporator a while back. If and when I need to open the system again I will probably change the condenser since I know that over time they become clogged and corrode.

        The one thing I wish I could do is flush the evaporator and housing without a full disassembly. If someone came up with a system to do this they'd get rich I think because the primary reason evaporators in vehicles go bad is from rotting leaves and debris that ends up at the bottom of the inside of the housing. If you could flush all that gunk out once a year the evaporator would probably last twice as long.

        That said, when I changed my evaporator I added green 1/2 filter foam to all the inlets behind the wiper tray to help keep some of that out. Not sure if it's doing the job but it should be as far as I can tell. Still, I really wish I could flush the evaporator housing once a year of so to flush the dirt, leaves, rotting bugs etc out. If you get a musty odor from your vents that is likely what you are smelling and you'll likely soon be needed an evaporator core. $$$


        • #24
          Long time span and long thread now! Glad to hear it's still working. I think you are right on evaps and debris that gets in there down thru inlets usually right at wipers (any vehicle) assorted effectiveness to keep stuff out. That and different places it's parked (under a tree?) or other source of yuk.
          I'd check that your foam doesn't degrade and be the next debris most things don't do well with heat, wet, cold and where I am ICE down there plus room from wipers to move BEFORE YOU TAKE OFF IN THAT CAR/TRUCK/Van or whatever.

          Also a cause to plug drain and flood interior so it all matters. Glad to hear it's working and your ideas of some solutions would like to know what and where the type of foam stuff is if you'll post it,
          MetroWest, Boston


          • #25
            Update: May 19, 2023

            I have to say it but...I have had ZERO problems with my AC in this vehicle since I started this thread. As of today it is still pumping out ice cold air and I couldn't ask for more. I have had to do nothing (except for the little freon I added last year due to under charging it initially.)

            I am posting this for anyone unsure about using the flushing process I used. I'm cheap and don't like spending what I consider excessive money for something simple. I successfully flushed this system that was full of metal shavings for under $20 IIRC.

            My idea with the process I used has been a resounding success...so far.

            I will faithfully report when it fails. It will eventually. Even new cars only go about 10 years before the evaps rot out or leak.
            But at this point I couldn't be happier.
            I usually use compressors pulled off of junked cars in the scrap yard for like $35 so when I get more than a couple years of service I feel lucky. I'm no pro.

            The foam I used to filter the incoming air is that Green foam called Uni-Filter (Fine).
            Last edited by King-of-DIY; 05-19-2023, 10:04 PM.


            • #26
              Can't argue with still working this long!
              IDK why "Caravan's" eat evaps you said "rot" before 10 years old? IDK some (asst. ones, asst. set ups last indefinitely I dare say some plain break?

              Long thread time span and # of posts.

              Now just asking - what is this "green" foam you mentioned? As use for filtering air.

              Do you cut that for a specific shape and is it tolerant of oil, fuels, heat and cold - the extremes? I'll search it out as I want that stuff if so.

              IDK I see stuff for my own, generators, chainsaws etc. ages range from the 1940's up still work OMG oil baths (air bubbles thru oil) would be better off with cleanable filter IMO is permanent but do fail 40-75 years just doing without right now!
              MetroWest, Boston


              • #27
                Oil bath air cleaners do a better job cleaning the air than a new paper filter, Paper gets a very slight advantage in cleaning once it gets some time and dirt on it. Oil Bath cleans without increasing the the pressure drop across the filter, however it does require regular service that can't be measured on a restriction gauge to tell when service is needed.
                I serviced units as big as waste baskets and you'd be amazed how much dirt they trapped. They don't work by pulling air through the oil but by making a 180 turn right above the oil, dirt continues in straight line and is trapped by the oil (difference in mass between air and dirt) . Some oil mist is pulled onto the wire turning inside the filter and the air must pass a convoluted path through the oil coated turning, stopping any tiny partials that did make the 180 deg turn.
                I know many hate them, but if they are maintained they do a good job and don't increase the pressure drop across the filter in between service intervals.
                To each, their own, but I prefer them, no parts other than oil, that gets changed when the engine oil gets changed. They do have one place where they don't work well, Chainsaw is a good example, where the operating angle can change wildly in use.
                Last edited by Cornbinder89; 05-25-2023, 12:40 PM.


                • #28
                  Alway like your opinions and thoughts. I found the foam just not right now.
                  Oil bath is a '48 John Deere (looks like middle 2 of a 300CID six) famous thing, Model M. Updraft carb - nice fuel is higher = no fuel pump.

                  Air comes in high up, a mushroom also would vent and not allow water in. Goes down to oil bath. Oh me - had the thing since 1972 dumped it out, rubber hoses had given out put window screen over it and a clamp. No dust scene for it's use is/was family owned used opted for OE snow plow still there hydraulic lift from rear 3 point hitch!

                  90% of use was for snow - no dust. It's there now with the hoses done in '87 because I killed it in a long puddle washed out UP COMES WATER! Chug and bang busted both pistons just them but did bearings while there still runs as new OE parts sketchy now to find + forget dealers! They used to for anything they ever made?

                  I'm not concise but now age getting to me, duh it's standard shift, no synchros you learn that 99,999% of folks today fail at standards this would make them walk - LOL.

                  "H" pattern shifter 1st in the middle, 2nd left and up, 3rd over right + up, 4th right under 1st and reverse under 2nd.

                  Throttle on stick up at wheel. Dual rear disc brakes can steer with too will pirouette on either one.

                  No water pump convection cooling heat rises fan cools it so drops passively. Still the same brass radiator!

                  Electric start manually pull on GM starter the solenoid! Crank possible thru hole in front - don't have it not strong enough anyway if 6V, POS ground battery is weak always point downhill :-)

                  CAN YOU TELL I LOVE THE THING?

                  No A/C you're out in weather the OE top was WWII canvas with see thru panels (some inferior plastic of the day) did fail the rest of any plastic is Bakelite! Now LMAO to tell now rub on the real stuff it smells like a molasses that's burnt.

                  One more, original owner's manual - covers all specs and "how to" for tune-ups and all adjustments were DIY have the common spares - I do still!

                  BTW it's street legal lighting and all for the time! No highways - there weren't any - laugh,
                  MetroWest, Boston


                  • #29
                    I have 2 K-7's (IHC trucks from the 40's) both have the oil bath A/C. I have a Dart with a real old 6-71 Detroit with a triple oil baths.
                    The British buses had oil baths the size of a waste can and took over a gal of oil. The air intake was on the right side (street side if you have RHD/ drive of the left side of the road). In Chicago, that ment curb side and a lot of dirt got kicked up (engine behind the rear wheels). They did a heck of a job and didn't have to source air filter replacements from over the pond like we did for fuel and oil filter. Some of the engines had centrifugal oil filter (bypass type) and nothing else, they also worked great and no running after filter.


                    • #30
                      The K's, doing a little "logging" on the property.
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                      • #31
                        Hello Tom.
                        My old VW Beetle had an oil bath filter.
                        It's not practical (imo) in this application so I used the green foam UNI-FILTER instead.
                        All I really wanted to do is protect the air intake ports behind the wiper tray from sucking in leaves and tree droppings.

                        I just cut it to fit the intake ports and used rectangle Harbor Freight Magnets to hold it in place.

                        The AC on the 2006 Caravan is still working great, but the AC compressor on my other, older Dodge Grand Caravan just failed and so I have to do the AC dance now with my older DGC. I'll be replacing the evap core AND the Condenser core on this one along with the compressor.

                        I came back here specifically because I had forgotten what I had used to flush the 2006
                        I'll be using the denatured alcohol again for sure.


                        • #32
                          Laugh - the old Beetle! Some no drain plug, some just a screen.

                          Do what it takes to keep especially pine needles out get thru OE intake screens. IDK if that comes off try for some "no see-'em" bug screen" used at my house bugs got thru the BITE WAS NO FUN!

                          Debris down there is a nightmare. Rest his soul my late Dad used to park under a tree clogged it right up pine pitch and all. All that to stay in shade ruined that car no miles and took care of it otherwise a '95 (?) Buick LeSabre Limited,. all toys. Do what you have to do test a sample if add a screen that it can take heat, cold and easy to replace if needed doesn't break up and then have to clean that out. If it stinks from rot try a Lysol down there try to kill yuck that rots,

                          MetroWest, Boston


                          • #33
                            Originally posted by Tom Greenleaf
                            Laugh - the old Beetle! Some no drain plug, some just a screen.
                            My 1970 (mine since 1972) and my 1971 Convertible (mine since 1976). I have oil filters in both, 1835cc engine in the convertible.