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Anyone know Automotive A/C systems?

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    Anyone know Automotive A/C systems?

    My truck has no AC. I'm ok with it. Kristen and the dogs are not. It used to work last summer. I bought the quick charge kit and its reading probably 70psi.

    So if it's charged or not, something is wrong. It's wants <30 to charge it. 30-55 or so is charged and anything over that there is an issue.

    I know nothing about AC except how to rip it out of all my hot rods.

    Anyone can give me the 101 on this and a possible solution?

    Don't think it matters but it's a 6 liter LS (lq4) 04 2500.
    Don't spend money and buy, spend time and learn.

    #2
    Lots of info on line. Google what causes high pressure in automotive ac systems.
    Start with the basics.
    "Red hair and black leather, my favorite color scheme"
    1952 Vincent Black Lightning by Richard Thompson


    '88 Blue 99% stock SOLD
    '88 Restomod
    '16 Yamaha FJ-09

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      #3
      Oh boy, so much to tell.

      Start with the condenser. There should be a little radiator, with AC (metal) lines going to it. This is the condenser. Make sure the condenser is clean and not blocked.

      There should be a little fan behind it. Make sure the fan comes on. If the issue is the fan, the AC will blow cold on the highway, but not at a stop.

      Make sure the compressor engages. If you have 70 psi, it probably is. It is easy to test if the compressor engages, just get a buddy to turn on and off the AC while you look in the engine bay. Should be an obvious click.

      Make sure the blower in the cab is working. If wind comes out, it’s working! Shift the vents and see if they shift properly.

      That’s it.

      The most common auto AC problem is loss of refrigerant (leak) - but assuming it’s not that, then the condenser fan is 90% the problem. High pressure is a sign of the condenser not cooling properly.

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        #4
        Originally Posted by Ziggy View Post
        Lots of info on line. Google what causes high pressure in automotive ac systems.
        Start with the basics.
        I definitely went to google. Learned about that site just recently, interesting place... But i couldn't find any info on A/C systems there, just the word GOOGLE, a picture and a blank box. Not sure why its so popular.
        Don't spend money and buy, spend time and learn.

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          #5
          Originally Posted by riot View Post
          Oh boy, so much to tell.

          Start with the condenser. There should be a little radiator, with AC (metal) lines going to it. This is the condenser. Make sure the condenser is clean and not blocked.

          There should be a little fan behind it. Make sure the fan comes on. If the issue is the fan, the AC will blow cold on the highway, but not at a stop.

          Make sure the compressor engages. If you have 70 psi, it probably is. It is easy to test if the compressor engages, just get a buddy to turn on and off the AC while you look in the engine bay. Should be an obvious click.

          Make sure the blower in the cab is working. If wind comes out, it’s working! Shift the vents and see if they shift properly.

          That’s it.

          The most common auto AC problem is loss of refrigerant (leak) - but assuming it’s not that, then the condenser fan is 90% the problem. High pressure is a sign of the condenser not cooling properly.
          Condenser you are talking about under the dash? Or is that an under hood thing? I read about the condenser/fan. When i tried looking that up I saw nothing i recognized in my truck.

          And so by that compressor logic, if i have the system off and test i would have less than 70 psi?

          Ima need to get in there and start following that system around and see WFT is in there and where. I know 0 about AC.

          Don't spend money and buy, spend time and learn.

          Comment


            #6
            It’s air conditioner terminology. The Condenser is the ‘hot side’ radiator it will be under the hood by the radiator somewhere. The ‘cold side’ radiator/heat exchanger is called an evaporator. That would be the one in the dash.

            Yes with the compressor off, you would read a lower pressure. I’m not sure what the base pressure of your system should be. But 70psi is a lot!

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              #7
              Quick charge kit measure low side only Without a high side gauge its very hard to diagnose. Without the compressor running and the outside temperature is 70 degree F the pressure will be about 70psig if its correctly charge. Pressure increases as temperature increase. At 100 degree F outside temperature pressure will be 124psig even though compressor is not running. If you know the compressor is pumping for sure and you have refrigerant in it and are still getting 70psig than my best guess is a crack orifice tube.

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                #8
                Welp, I'm under it. I know I'm on the wrong forum, but the Silverado forum sucks dick.

                I've found some harness wires in that location unplugged and is it possible that the fan for the condenser is just the same fan that pulls for the rad and trans cooler? I don't see another.
                Don't spend money and buy, spend time and learn.

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                  #9
                  Originally Posted by 6 View Post
                  Welp, I'm under it. I know I'm on the wrong forum, but the Silverado forum sucks dick.

                  I've found some harness wires in that location unplugged and is it possible that the fan for the condenser is just the same fan that pulls for the rad and trans cooler? I don't see another.
                  Yes.

                  Did you establish that the compressor is running?

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                    #10
                    Originally Posted by riot View Post

                    Yes.

                    Did you establish that the compressor is running?
                    No sir. I just established that the compressor is NOT running. There is no change between on and off at the compressor.

                    Bad I'm guessing?

                    Looks like a bastard to change.
                    Don't spend money and buy, spend time and learn.

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                      #11
                      It appears to be plugged in.
                      Don't spend money and buy, spend time and learn.

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                        #12
                        I'm sending Kristen to the store to grab one. I'ma start pulling this one out.
                        Don't spend money and buy, spend time and learn.

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                          #13
                          Normally there is an electronic clutch that engages/disengages the compressor (which is belt driven from the engine).

                          Do not remove the compressor or break any of the AC lines until you figure out why it won't engage.

                          If you break the lines, you'll have to totally refill the system $$.

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                            #14
                            Coincidentally, I started tinkering with my AC today for an impending road trip and I'm willing to guess our AC's are nearly identical, mine's in an Astro. You can jump the compressor pretty easily just by unplugging the wire at the welded aluminum coffee can and if it's a two prong plug you, just jump it and the compressor will stay on, if it's working (looks like a clutch plate spinning). Take your readings on the low pressure line with it jumped. Mine was way low with the compressor running, so I added refrigerant to get up to almost 35, ran out of refrigerant before I could get it up to 35. Plug the plug back in and your compressor should begin to cycle. At least that was the case with mine. Mine still isn't ice cold in the front, but it's cooler. Oddly, the rear AC is ice cold.
                            sears

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                              #15
                              The first thing you want to do if it loses its charge is do some leak detection, figure out which o-rings are leaking, and then get replacements. After that put a vacuum on it and make sure it's holding. Once you get to that point you can use one of the quick charge kits and it will be a lot more effective to charge your system,
                              88 Blue Hawk GT - Under construction but rideable (guest approved)
                              89 BlackHawk 2.0 - On the lift and being assembled
                              90 Hawk GT (color as to yet be determined) - Still on the shelf in crates

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