Factory AC Will Freeze You Out

Heating / Cooling / AC

  1. Jim Kueneman

    Jim Kueneman FABO Gold Member FABO Gold Member

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    FINALLY the Daughters Duster will freeze your nipples off. I will try to limit my rant of aftermarket parts. The POS aftermarket expansion valves flood the evaporator and I went through 3 compressors where the super heat was totallly wrong on the valve and flooded liquid into the compressor failing the reed valves. Bought NOS reed valve plates and a NOS expansion valve (yes it is R12 BUT THAT DOES NOT MATTER). I plan to tighten the spring in the valve on turn in to compensate for the R134A with this valve but all the problems are gone and it is flipping cold 32F on the road on a 75F afternoon. Oh and this was no more than an O’Rileys rebuilt compressor.

    4CAA2EC1-174C-49F1-A4E4-28265B00A407.jpeg 694BF7D9-5CFD-4084-9A0A-409E427A0CA4.jpeg
     
    Last edited: Apr 16, 2021
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    • pishta

      pishta I know I'm right....

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      I got my propane (R290) filled R12 system down to 45F out the vents on an 80 degree day. Not bad for lantern fuel! I use propane (R290) as R134 in CA is $25 a can and my shit leaks so I'm only spending about $2 on a refill and its ozone safe.
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      • BillGrissom

        BillGrissom Well-Known Member

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        I use Duracool refrigerant w/ their PAO68 oil in all my cars, even the 2002. It is mostly propane. Envirosafe is similar. Cools well, claimed slightly better than R-12. I ignore the rants about "explosive" since those people know nothing about combustion and used in millions of cars with no fires reported, other than an Australian AC tech who purposely made a fire to diss it. It is only 6 oz, so less dangerous than carrying a newspaper in the cabin.
         
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        • RustyRatRod

          RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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          Well yeah it does "matter" cause R12 has always cooled better. lol Glad you got it workin good!
           
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          • teringer

            teringer Well-Known Member

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            you could install a adjustable low pressure switch / like everyone else uses and set the desired temp
             
          • Jim Kueneman

            Jim Kueneman FABO Gold Member FABO Gold Member

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            That was my next step if the factory valve did not work.
             
          • Mike69cuda

            Mike69cuda 66 is the new 17 FABO Gold Member

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            My factory ac that I installed from out of a dart works great with R134. I am no expert, but I have always thought that getting a good evacuation prior to charging is a key to getting it to operate well. I usually leave my vacuum pump on for a few hours after the system has been open.
             
          • Jim Kueneman

            Jim Kueneman FABO Gold Member FABO Gold Member

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            So do I, you have to get all the moisture out.
             
          • scatpackbee

            scatpackbee Well-Known Member

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            Have you got a part number for that switch?
             
          • teringer

            teringer Well-Known Member

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            any switch from a ford /from the 80's should work just pull out the rubber cover on the inside of the switch there will be a screw you can adjust ,wound you install it at the compressor or splice the line near the evaporator
             
          • Jim Kueneman

            Jim Kueneman FABO Gold Member FABO Gold Member

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            I am going only going to partially agree this may work. The aftermarket 4 Seasons, Parts Store, and even the OEM are fully adjustable though you have to pull the line off to get to the barrel to tighten or loosen the spring. What is wrong with the aftermarket it the valve will not close down far enough in a static state for the evaporator. It had nothing to do with the spring tension adjustment. If these can adjust the static position of the valve then I agree they could be better. If they can't then they may or not be any better than the aftermarket.

            I ordered spare valves so I can try to rig something up to measure the static pressure drop across them then figure out how to shim the aftermarket to achieve the same pressure drop... someday.
             
          • j_anderson

            j_anderson Well-Known Member

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            I have my existing factory expansion valve. Wondering how I can tell if its still usable. I bought the car in 96 but the AC has never worked. Now that I’m restoring her, I want all the systems working. Do expansion valves go bad? How can I get mine checked? If its bad, can you link me to a good source for an OE valve or supply the correct part number for a ‘72 swinger?

            TIA
             
          • 67Dart273

            67Dart273 FABO Gold Member FABO Gold Member

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            Sure they do. The vacuum diaphram can fail and leak, and the mechanical part of a valve can fail just any other moving part

            Only way I know to test it is get the system ready, evaculated and charged and up and running and see what you have

            So far as replacement, "I've never done this" in automotive, but if you can access industrial refrigeration supply joints there are all kinds and all sizes of TXV/s for sale. If you can silver braze/ work with fittings etc you ought to be able to adapt one.

            There are two major deviations. The kind with the small extra (usually 1/4") line hook up are called "externally equalized". Types without this are called "internally equalized". The external type is better for widely varying situations, as the pressure tap for the evap gives the valve a "better picture" of the pressure situation. Of course you want it sized within reason, and for the R you are working with

            Some of them are adjustable and some are not, which gives you a further "diddle factor" when replacing one

            "Good luck" trying to buy a new R12 valve, 'xcept maybe egag or somewhere

            From wiki:

            506px-Thermostatic_expansion_valve.svg.png

            Adjustment of the screw if present at bottom "encourages" valve opening by weakening spring pressure. A drop in temp on the bulb (at evap outlet) causes the valve to throttle down, and an increase in equalizer pressure causes the thing to throttle down
             
            Last edited: Jul 19, 2021
          • harrisonm

            harrisonm Well-Known Member

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            Speaking of R12, I have a friend who has about 6-8 of the 12 ounce (or so) cans you used to be able to buy for a few bucks. He doesn't need them. Are they worth much?
             
          • toolmanmike

            toolmanmike Moderator Staff Member FABO Gold Member

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            Give him a few bucks. They aren't worth much. Nobody uses them much any more. I got a couple to charge up mine after a hose blew. The guy gave them to me. He knew he would never use them.
             
          • RustyRatRod

            RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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            No. Some people hoard them but they ain't worth anything. R134a can cool just as good if you know what you're doing.
             
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            • toolmanmike

              toolmanmike Moderator Staff Member FABO Gold Member

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              Yep. I can get my pick up down to mid 30's
               
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              • pishta

                pishta I know I'm right....

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                Here in CA they go for about $20 a can at swap meets. seen em as high as $40 but $20 moves them. Getting less popular now.....When I was in TExas, I saw R-134 for like 2.99 a can at H.E.B so I bought 5 and brought them back to CA with me in the trunk.
                 
              • jos51700

                jos51700 Green Bearing thread connoisseur

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                Since I have a magnum swap, I was just going to use everything from the donor Ram except the evaporator, and connect it all to the factory Dart evaporator using some custom hoses.

                Any reason I can't do this?
                 
              • townsend

                townsend Well-Known Member

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                Part number for Chrysler expansion valve was 2932843 which was superseded to number 3703651. Look at the price people are paying for a can of Freon 12 on eBay.
                 
              • RustyRatRod

                RustyRatRod I was born on a Monday. Not last Monday. FABO Gold Member

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                None whatsoever.
                 
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                • toolmanmike

                  toolmanmike Moderator Staff Member FABO Gold Member

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                  Do it.
                   
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                  • 67Dart273

                    67Dart273 FABO Gold Member FABO Gold Member

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                    NONE. You will have to "adjust the charge" because two things.........Going from R12 to 134 charge weight is different, but here you are building a one-off custom system. You need to learn to charge by superheat and subcooling, and to "anticipate" (and or recheck readings) at different conditions of operations

                    For example........If you charge it up (stationary of course) on a cool day, with plenty of "blower" into the radiator, and if the interior is fairly warm, then on a warmer day the higher head pressure may push more refrigerant back under some conditions and cause a danger of flooding to the compressor.

                    This can be a real issue, and in the case of bone stock systems, the charts in the manuals have all this (allegedly) thought out for you.

                    Worst conditions for low side end to cause flooding back is when interior is COOL Depending on the system, the high side contribution can be worse either in cooler conditions or warmer conditions. So you need to check for both Superheat is your friend.

                    You do this by taking the temperature of the low side line coming back to the compressor. You need to wrap it with something to insulate the temp sensor and avoid erroneous readings from engine heat.

                    Now you look at the pressure of the low side, and go to a chart, convert that across to temperature. The difference in your two temp figures is the superheat. I would not want to see less than 10-12F superheat under worst conditions.

                    As superheat drops towards zero, you get more and more liquid droplets going back to the compressor
                    Subcooling in a case like this is secondary, but gives you an idea of what the condenser is doing. It is similar to superheat. You take the temp of the liquid line leaving the condenser, and read the high side pressure, and convert that to temperature. Again, the difference is subcooling. Generally, the higher the reading, the more efficient the condenser is working. Low readings can mean dirty/ too small condenser, undercharge, or that system is trying to work way above it's capacity (overloaded, hot day)
                     
                  • Mike69cuda

                    Mike69cuda 66 is the new 17 FABO Gold Member

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                    I ordered a new expansion valve, dryer and evaporator off eBay a few years ago. I charged it with R134 and it works great.

                    I have been charging ac’s for years as an amateur, but I am still basically at the idiot level.

                    Here is my idiot procedure which I think most people with some reasonable level of skill could do.

                    1. Vacuum out the system really well, let the pump run a few hours at least.
                    2. Be really careful how you operate the valves so you don’t put air back in the system. Purge your lines.
                    3. Get a bucket of hot water to dunk your can of R134 in. As the gas leaves the can, it cools down reducing the pressure in the can. You may need to get a second bucket if the water cools too much.
                    4. Get out your garden hose and hose down the evaporator while you are charging. The idea is to keep the pressure in the can higher than the pressure in the system so it will charge.
                    5. Don’t be in a hurry. Stop between cans and let the system equalize.
                    6. Charge until the low side hose on the compressor gets cold and starts sweating. If it freezes, you probably put too much in.
                    7. After the line starts sweating, you are probably full or about there. Take it for a drive & see. If it cools good you are done. Don’t be a perfectionist.
                    8. You will use about 50 -75% as much R134 as the R12 sticker says.

                    Disclaimer: I am not an expert, nor do I understand a lot of this. I just do the same thing over every time and it works for me. As long as my ac cools good, I am a happy idiot….
                     
                  • 67Dart273

                    67Dart273 FABO Gold Member FABO Gold Member

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                    You mean condenser which is the part in front of the radiator.

                    Also when charging an empty system, you can get ahead of the game at the initial charge:

                    1...As said CAREFULLY think through your manifold procedure, and purge hoses. WHEN THE SYSTEM IS EVACUATED THE HOSES WILL BE UNDER A VACUUM TO THE MANIFOLD SO DON'T PURGE the hoses between manifold and system.

                    ONLY purge (with can upright) the hose from can to manifold.

                    2...For INITIAL charge, leave engine off, turn can upside down to get liquid, and dump as much as you can into the HIGH side of the system. That's right, LIQUID, into the HIGH pressure side. This liquid will go around through the condenser, through the metering, through the evap, and evaporate and vaporize before reaching the low side of the compressor. You can ONLY do this with compressor STOPPED

                    Doing this, however, gets a fair amount of charge into the system, and then you can start it, it will likely quickly cycle on/off on the low pressure switch. To get more into the system if the low pressure is cycling very quick you can TEMPORARILY bypass the low pressure switch. If you are inexperienced charge ONLY GAS into the low side. If you have experience you may charge liquid into the low side by CAREFULLY using the manifold valve as a metering device. DO NOT DO THIS unless you have some experience

                    Heating the can as mentioned using quite warm water works well, especially the 12oz cans
                     
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