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2007 PT Cruiser high pressure

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  • 2007 PT Cruiser high pressure

    Working on a 2007 PT Cruiser. Just replaced the compressor, accumulator and orifice tube. Added one Oz of Oil to new accumulator and new (reman) compressor came with three oz of oil. Vacuumed for 45 minutes and added 12 Oz of 134a. Low side climed to 135 and high side went to 450. I shut it down, reclaimed refrigerant and opened all lines and applied shop air. Nothing was plugged. I ordered another compressor, but I'm not confident in that decision. Any suggestions?

  • #2
    Low side at 135? that would be static pressure for 105 degs. What was the temp? High low side with the compressor running indicates a restriction between the low side tap and compressor. A rising low side with the compressor on means also is a sign of a restriction. Is the low side tap on the accumulator?
    What happened to the system before the work was being done? Sudden compressor failure? What did the screen look like on the old orifice tube? Was there metal on it?
    You've got a serious problem but we need more info if we are going to be of any help.

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    • #3
      When this car first came in the vent temps were cool but occasionally it would lug down and almost stop the engine. When this happened it would also spew a little refrigerant. I assumed a restricted orifice and also assumed the system would be dirty. Replaced the compressor, orifice tube and accumulater. The orifice was built into the line so a visual inspection was not possible.

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      • #4
        Many condensers can not be flushed clean and need to be replaced if the system suffered a major problem, but that would not cause high or rising low side pressure.
        What are your pressures at rest and what happens when the system is turned on.
        Not the 1st with an orifice tube in the line, generally worth while cutting the line open to inspect what the tube looks like to have an indication how badly messed up the whole system is.

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        • #5
          Today I reassembled everything with a new (reman) compressor. After a 45 minute vacuum I added one 12 Oz can if refrigerant and started the car. When the compressor engages my high side goes off the dial and the low side drops to 90. When the compressor kicks out (I assume by the high pressie switch) the high side falls to roughly 300 and the low side stats around 120. At rest, key off the stay at 150 - 160. I took a video of the guages and moved over the system with a temp gun. Line temps were around 119 and condenser temps were 150 to 170 movivd from the bottom to the top.

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          • #6
            I'd have to question your gauge accuracy 160 would 115 deg, what is the temp of the air around the condenser with the system at rest?
            You have serious problems. I asked some question in post #2 which you haven't answered so I can't help further
            Last edited by Cornbinder89; 07-25-2018, 07:43 PM.

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            • #7
              Right at 100 degrees.

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              • #8
                If underhood temps are 15 deg higher than surrounding air, 160 psi would be right.

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                • #9
                  The low side tap is on the line adjacent to the accumulator. That line also houses the orifice tube. I opened up the old line and the orifice tube was clear. No metal, no gunk. I'm can`t seem to get my head around why a low side restriction would cause rising pressure. Seems like it should cause a lower reading, maybe even a vacuum??

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                  • #10
                    If the restriction is between where the gauge is connected, and the compressor, the pressure will rise in the low side gauge while the line beyond the restriction will be low, but the gauge will not show it.
                    Are you saying the orifice tube is in the low side line? that doesn't make sense. or are you saying that the low side tap is right after the orifice tube? If that is the case, the restriction could be in the evaporator itself.
                    I must admit I am having trouble visualizing the system lay out.
                    If the gauge tap is before the orifice tube, than it will read high side pressure.

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                    • #11
                      Yes the orifice tube is in the low side line, near the compressor. Makes no sense to me either. I tried to upload a pic but it was too large. I'll resize and try again tomorrow. ALSO: I put a high volume fan in front of the condenser and my head pressure came down to 350, but the low side kept creeping up front 80 to about 95.

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                      • #12
                        Can't be, if the evaporator is on the high side of the system, no heat transfer can take place, the refrigerant must boil (go thru a phase change from high pressure liquid to low pressure gas) for there to be heat absorption. The control device (orifice tube/Tx valve) must be before the evaporator. It can be anywhere between the outlet of the condenser to the inlet of the evaporator. Most common is right before the evaporator but some have been placed in the outlet of the condenser.
                        The refrigerant control be it orifice tube or Tx valve is the separation point between high and low sides. once the liquid passes the metering device it goes from high pressure liquid to low pressure liquid and immediately starts to boil and absorb heat.
                        Designers of systems can do a lot of things, but they can't change the laws of physics. Or as one guy I know likes to put it "remember, they aren't called the gentile "suggestions" of physics" !

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                        • #13

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                          • #14
                            The low side tap is near the accumulator, not the compressor and just upstream from the orifice tube. I just re-read my previous post and saw my mistake

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                            • #15
                              Makes more sense now. If low side rises with the compressor on, above 60-70 psi I would guess your restriction is between the tap and compressor somewhere.
                              with the system at rest, the high and low should be the same, when the compressor is on the low side should dip, it may start to rise back up but shouldn't go back to where it started or above that. It will also rise if the compressor cycles off for any reason.

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