FuzzFace2 Posted July 5, 2022 Author Share Posted July 5, 2022 Usually with that big a difference something is restricting the flow, but, if you are still getting gas through to the orifice tube it can give strange results. Does your system have one of the quick connect fittings in the liquid line from the condenser? I have seen these come apart internally and partially block the line. No it has the high side by the compressor and the low side is up by the dryer. this is why I was asking. it is behaving as though it has a clogged orifice tube. the compressor creates differential, yet the orifice regulates it. I'm more concerned of this due to you saying earlier that there was contained pressure in the evaporator after evacuation and it was released upon removal of the orifice tube. sure sign of a stuck tube and I certainly hope you did not reinstall the same one. if you did then that would explain the system not drawing from the can. I did not "evacuate" like you maybe thinking I had the system open to replace the leaking o-ring, it was the service valve to the compressor manifold that was leaking. If put that back together and moved on to the orifice valve. Being it was open I figured to pull the orifice valve to see if it had any junk in it because the evap was used and open for a few years but I did flush it out and used shop air to make sure when I first got the system working a year ago. Yea I was a little thrown off that there was PSI when I pull the valve and it pushed the oil out. But thinking maybe the compressor had something to do with still holding some pressure? I cant get back on it for a few days, work hours just kill me this way. But I will check a few things and see if I cant get some where with it. Thanks fore the help so far. Dave ---- Link to comment Share on other sites More sharing options...
Machspeed Posted July 6, 2022 Share Posted July 6, 2022 Usually with that big a difference something is restricting the flow, but, if you are still getting gas through to the orifice tube it can give strange results. Does your system have one of the quick connect fittings in the liquid line from the condenser? I have seen these come apart internally and partially block the line. No it has the high side by the compressor and the low side is up by the dryer. this is why I was asking. it is behaving as though it has a clogged orifice tube. the compressor creates differential, yet the orifice regulates it. I'm more concerned of this due to you saying earlier that there was contained pressure in the evaporator after evacuation and it was released upon removal of the orifice tube. sure sign of a stuck tube and I certainly hope you did not reinstall the same one. if you did then that would explain the system not drawing from the can. I did not "evacuate" like you maybe thinking I had the system open to replace the leaking o-ring, it was the service valve to the compressor manifold that was leaking. If put that back together and moved on to the orifice valve. Being it was open I figured to pull the orifice valve to see if it had any junk in it because the evap was used and open for a few years but I did flush it out and used shop air to make sure when I first got the system working a year ago. Yea I was a little thrown off that there was PSI when I pull the valve and it pushed the oil out. But thinking maybe the compressor had something to do with still holding some pressure? I cant get back on it for a few days, work hours just kill me this way. But I will check a few things and see if I cant get some where with it. Thanks fore the help so far. Dave ---- Like Mat, I was thinking an orifice tube issue or perhaps the evaporator core is plugged. Is your system 134? Here's good diagnostic chart for you: Link to comment Share on other sites More sharing options...
mat in tn Posted July 7, 2022 Share Posted July 7, 2022 Like Mat, I was thinking an orifice tube issue or perhaps the evaporator core is plugged. Is your system 134? Here's good diagnostic chart for you: one of the dynamics of a fixed orifice refrigeration system whether it be one of our trucks or a window air conditioner or even the old deep freezer in the garage. is that the compressor creates pressure and by doing so, a positive flow of refrigerant. it must squeeze through the capillary portion of the orifice to get to the evaporator on the other side. this "damming up" of pressurized refrigerant allows the differential of the two pressures. suction side and discharge side. low and high. as soon as the compressor is turned off whether by the switch or turning off the truck, the system begins to equalize the two pressures. through the orifice! not through the compressor because the compressor uses a means of check valves. the only way for it to have contained pressure after being open for more than a few minutes is for the orifice to be clogged. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted July 7, 2022 Author Share Posted July 7, 2022 Like Mat, I was thinking an orifice tube issue or perhaps the evaporator core is plugged. Is your system 134? Here's good diagnostic chart for you: https://forum.garysgaragemahal.com/file/n121274/AC_Evaluation_Chart.png Yes it is 134a I will look over that chart better this weekend as it should be cooler and I will have a good head on me by then. Been getting up at 12 am for work working out side in 97*f heat and 100% humidity and not raining! one of the dynamics of a fixed orifice refrigeration system whether it be one of our trucks or a window air conditioner or even the old deep freezer in the garage. is that the compressor creates pressure and by doing so, a positive flow of refrigerant. it must squeeze through the capillary portion of the orifice to get to the evaporator on the other side. this "damming up" of pressurized refrigerant allows the differential of the two pressures. suction side and discharge side. low and high. as soon as the compressor is turned off whether by the switch or turning off the truck, the system begins to equalize the two pressures. through the orifice! not through the compressor because the compressor uses a means of check valves. the only way for it to have contained pressure after being open for more than a few minutes is for the orifice to be clogged. I did give that some thought that the compressor "check valves" could hold the pressure back a little as I did not have the line off for vary long. What dose it take to pull the line, pull the old ring off and match for the size, oil it and stick it back together? Being the system was open for the o-ring I figured I would check the orifice valve if plugged. That was when I pulled it it has some pressure behind it but the valve was clean. I will look into what Bill said of the hose or adapter seals blocking so the change will not go in. After not being able to charge and get the system cooling I had to walk away before something bad happened Thanks for the help guys Dave ---- Link to comment Share on other sites More sharing options...
mat in tn Posted July 9, 2022 Share Posted July 9, 2022 Like Mat, I was thinking an orifice tube issue or perhaps the evaporator core is plugged. Is your system 134? Here's good diagnostic chart for you: https://forum.garysgaragemahal.com/file/n121274/AC_Evaluation_Chart.png Yes it is 134a I will look over that chart better this weekend as it should be cooler and I will have a good head on me by then. Been getting up at 12 am for work working out side in 97*f heat and 100% humidity and not raining! one of the dynamics of a fixed orifice refrigeration system whether it be one of our trucks or a window air conditioner or even the old deep freezer in the garage. is that the compressor creates pressure and by doing so, a positive flow of refrigerant. it must squeeze through the capillary portion of the orifice to get to the evaporator on the other side. this "damming up" of pressurized refrigerant allows the differential of the two pressures. suction side and discharge side. low and high. as soon as the compressor is turned off whether by the switch or turning off the truck, the system begins to equalize the two pressures. through the orifice! not through the compressor because the compressor uses a means of check valves. the only way for it to have contained pressure after being open for more than a few minutes is for the orifice to be clogged. I did give that some thought that the compressor "check valves" could hold the pressure back a little as I did not have the line off for vary long. What dose it take to pull the line, pull the old ring off and match for the size, oil it and stick it back together? Being the system was open for the o-ring I figured I would check the orifice valve if plugged. That was when I pulled it it has some pressure behind it but the valve was clean. I will look into what Bill said of the hose or adapter seals blocking so the change will not go in. After not being able to charge and get the system cooling I had to walk away before something bad happened Thanks for the help guys Dave ---- one of the best suggestions I can make is to start with a new tube. these are not expensive at all and not worth reusing if at all questionable. the orifice is a tiny capillary tube housed inside the blue plastic with the white cap. the sieve screen covers all it can but if the system was "open" for even one season worth of environmental changes, the "brass" orifice tube could easily corrode or even gunk up to the point of clogging itself and no debris even be visible on the screen. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted July 10, 2022 Author Share Posted July 10, 2022 one of the best suggestions I can make is to start with a new tube. these are not expensive at all and not worth reusing if at all questionable. the orifice is a tiny capillary tube housed inside the blue plastic with the white cap. the sieve screen covers all it can but if the system was "open" for even one season worth of environmental changes, the "brass" orifice tube could easily corrode or even gunk up to the point of clogging itself and no debris even be visible on the screen. I really dont think it is the valve. I say this because when I added the first can I used the gauge set hoses that has a 134 quick adapter and the whole can did not go in. I then placed the can on the intake / exh manifold to heat it up some but still did not push the full can. I then used a short hose that has a gauge & valve that screws onto the can and hooks to a 134 quick connection. When ever I tried to add the 2nd can by opening the valve the gauge went into the red. That is telling me when ever is in the can was not going into the system. Now my truck has R12 to 134a quick adapters so I can use the quick adapters from the gauge set. Going with something Bill said of having a hose seal blocking the "path way" I wonder if the R12 to 134a adapter seal is blocking the path way and the only time I can "push" a charge in is if the cans are new. I did not get out to test that but I am going to remove the adapter and see if I can hook the gauge set up to the low side like I did when I first charged the system a few years back. At that time I could not check the high side as the gauge set hose would not fit the R12 fitting. I also want to get a can or 2 more just in case. As for the valve if it will not take any more charge I will look into deeper why and swap out the valve. Oh yesterday when I did the weekly trash run I turned on the AC. When driving the compressor would turn on & off because the low side would go to low. But at idle the compressor would stay running and I could feel the air coming out the vents was a little cooler and I checked the line at the valve and it had frost on it. I hope if I can get the compressor to stay running and have the right charge it will cool again. Dave ---- Link to comment Share on other sites More sharing options...
FuzzFace2 Posted July 10, 2022 Author Share Posted July 10, 2022 Like Mat, I was thinking an orifice tube issue or perhaps the evaporator core is plugged. Is your system 134? Here's good diagnostic chart for you: Edit: I was able to copy it to a word doc and print it out and can read it now Thanks Like Mat, I was thinking an orifice tube issue or perhaps the evaporator core is plugged. Is your system 134? Here's good diagnostic chart for you: https://forum.garysgaragemahal.com/file/n121274/AC_Evaluation_Chart.png John do you have a like to that chart? It is hard for me to read and would like to read it over better before I hit the truck again to fix this AC Dave ---- Link to comment Share on other sites More sharing options...
mat in tn Posted July 10, 2022 Share Posted July 10, 2022 Edit: I was able to copy it to a word doc and print it out and can read it now Thanks Like Mat, I was thinking an orifice tube issue or perhaps the evaporator core is plugged. Is your system 134? Here's good diagnostic chart for you: https://forum.garysgaragemahal.com/file/n121274/AC_Evaluation_Chart.png John do you have a like to that chart? It is hard for me to read and would like to read it over better before I hit the truck again to fix this AC Dave ---- in reference to the adapters. I know exactly what you mean. back about twenty years or so, a friend wanted to avoid this as a possibility, now he and I both have a lengthy air con history. that said we have multiple old gauge sets for different appliances and refrigerants. he took an old std. blue hose and cut it in half then took an old 134a blue hose and cut it. then spliced the required sections to make an adaptive hose for 134a guages to an old r12 car. we had the parts on the truck and no money spent. needless to say, we had a tool for years that "fit". no vehicle mounted adapters needed. im not saying that anyone should do this as it may or may not breach certain safetys or regulations:nabble_smiley_whistling: Link to comment Share on other sites More sharing options...
Bruno2 Posted July 10, 2022 Share Posted July 10, 2022 Here is my 0.02: Typically when a compressor is heading South the needles on the guages will twitch like they're nervous. This is because the pump isn't sealing and is letting the pressure slip from one side to the other. I think maybe you're too heavy on the oil in the system and this is causing flow issues. I think I would take it apart and use some alcohol to flush the lines and condensor to get some.oil out. It doesn't seem like the.orifice is plugged or the low side would be trying to go to vacuum and the high side would be higher than Willie Nelson. Link to comment Share on other sites More sharing options...
Bruno2 Posted July 10, 2022 Share Posted July 10, 2022 I prefer the orange orifice tube. I can make them blow cold with any of them. Another thing people don't like to consider because it's not that common is R152A is more of a direct replacement for R12 than R134A is. When swapping R12 to R152A use a multiplier of .55 for the charge. When saapping R134A to R152A use a multiier of .65 . So let's say the system calls for 10oz of R134A . 10 X .65 =6.5 oz is your R152A charge. Link to comment Share on other sites More sharing options...
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