A/C system

Discussion in 'Off Topic' started by davidsis, Oct 13, 2008.

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  1. davidsis

    davidsis Guest

    Why didn''t anyone tell me that the guages are to have the valves screwed shut to get an acurate reading? LOL, My 95 Lincoln has a reading of 0 on the low side and 100 on the high side, the manual says it should be Low 22-47 and the high should be 160-245. My other car not a lincoln but still need help is a 95 T-birds pressuer is Low side 25-50 guage jumps back and fournth with compressor coming on, and 75-100 on high side guage jump back and fourth with compressor running. The manual says it should be Low side 25-50 and High side 75-100. Any help is greatly appreciated. I think I might be able to do this myself if I have help. Please, I have a lot of free time now that the economy is so crummy.

  2. jimraysr

    jimraysr Member

    AC gauges

    Just saw you post.

    What refrigerant does your car have? I would expect
    a 95 would have R-134A, the replacement for R-12.

    Anyway when you see a low side, low pressure, you are low on refrigerant or you have a restricted expansion device.

    As your head pressure is also low, then it would seem you are low on refrigerant.

    Think of the system as two sections, one separated by the compressor and the other side by a restrictor or an expansion valve.

    The compressor takes low pressure low temperature gas and compresses it into a high pressure high temperature gas. (All the heat in the low temp gas is compressed into a much smaller space) Now thei high temp gas enters the condenser (in front of the radiator) and the air cools it till it condenses into a high pressure, high temp. liquid. The liquid goes to the expansion device and is sprayed into the evaporator which is at the low side pressure. the liquid boils in this atmosphere and in order to boil it must get heat from the air blown over the coil. Wala, air conditioning.

    It would seem you don't have enough gas to keep up with the capacity of the compressor? Then the compressor can't push enough gas into the condenser to become liquid (or very little) then back to the expansion device where your are passing more gas than liquid and the whole system isn't cooling very much.

    So with the outdoor temperature in mind, you need to add enough gas to get the gauges in the proper territory.

    All charges these days are made as 1.7# or 3.2 #, etc. they just dump in the proper amount in for the system. (generally posted on a nameplate), but that requires you dump all the existing gas, evacuate it wt. a vacuum pump and go from there. Wasteful if not not a bad green policy.

    I have a unit which recovers gas from a system if I need to open it up, but they cost around $900. So I would suggest you do it by trial and error until it cools and the gauges are in the ball park.

    Sorry, kind in a hurry to get to a meeting and my eyes are a little fuzzy this morning, so don't have time to find all the typos and misspellings just now.

    Will look at it later to see if there are any major errors. )

    I hope this is of help. If you have more questions, please emaol me direct. jamesraysr@gmail.com

    BTW, when I saw the title, I thought somebody was putting A/C on a motorized bike and I would love to have it on a 115 degree F day. )

    Guess I will have to continue using a personal mister for summer rides. Have to keep it off the glasses or the lenses will be white by the time you get to your destination. The liquid rock in our water is brutal.


    Last edited: Oct 20, 2008