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  • Refrigerant charge

    Hi, I have a 1990 geo metro that has been converted to r134a. When I bought the car, it had no charge in the system and now I want to start using the AC. My concern is that the car had a dealer aftermarket AC system installed in the car...not the factory system. Would the charge be the same same for a factory system and if not, how could I know how much to charge the system? Also, there is no sticker on the hood indicating what the charge should be for this system.

  • #2
    Answer is "NO" it wouldn't be a calculation of the OE original capacity. All is not lost just harder to first find where it's leaking. It can waste some refrigerant or mix of now 134a and nitrogen to gain pressure equal to the temp in Fahrenheit or close a couple ounces would do and unless heard leaking proceed to all ways to find leaks including soapy water, sniffers for refrigerant gasses I like best or plain oil evidence on connections, drain tube for evaporator and stains on condenser are strong clues.

    Note but somewhat ignore that most of these when OE and R-12 only held 18 ounces of refrigerant! The area of % of 134a maxes out at 80% of what is known and isn't but a good bet it's not a high capacity set up.

    Knowing how much oil is in it now or what type is about impossible without starting from scratch. Tweaking systems when you have no capacity known is very tricky and risky if starting from a well held vacuum you do want to feel warm outlet lines and cold return lines in no time to circulate oil or it's all over or might be now?

    What do you want to do? First would be finding where it leaked. Then I would spin compressor by hand or carefully by the outer hub to see if it turns at all or very rough feel.

    Would probably if low port close put 1-2 ounces of Ester oil (a guess now too on type) directly into a line or fitting to compressor to spin some thru for next start up so it has lube for any chance of this working without burning it up.

    Can't know but look how close low side port is to compressor or take the line off and replace any "O" ring or gasket if you add some oil highly suggested.

    This seems like it's going to be a short lived system both this old, unknown if parts available so you decide if you wish to give it a try at the risk of losing some bucks to find out if it can work again at all or be fixed plus if the costs would exceed some total new aftermarket set up or just do without being more costly than it could be worth for a whole vehicle??

    Decision time. What do you wish to do and how much equipment if any do you have for gauges and leak finding?

    MetroWest, Boston


    • #3
      If the system is empty now, I would go ahead and remove the compressor and drain it, then re-fill with fresh oil for 134a in the viscosity the compressor make calls for. More compressors are lost due to lube issues than anything else. Starting with a full oil charge in the compressor will help. If you know the make and model of compressor we can tell you the oil cap it needs.
      It would help to know if it is an orifice tube or Tx (expansion valve) system, Orifice tube systems are much more picky when it come to amount of refrigerant than Tx system.


      • #4
        Jlober09 and Cornbinder89: TMK there were some exact fit aftermarket systems for some cars that didn't appear aftermarket like hanging under the dash or from a hump on the floor types or ages ago that barely worked for the few I knew of. Nacho knew of custom ones. Trouble seems they come and go or bought up and rebranded part of not having info.

        Tx or CCOTs I only recall Tx set ups.

        For now if more info isn't know I suggest keeping the attempt costs reasonable especially if it's been down for a while. Chances are going to take some very careful guessing at the approach on this with unknown results until getting into it,

        MetroWest, Boston


        • #5
          I remember those from the '80's. At that time the base model cars often came with 4 cyl engines that the OEM wouldn't offer A/C on. If you wanted A/C you had to opt for the V6. There was a brisk business selling aftermarket conversions, and salesman wouldn't disclose it was aftermarket. Made for some unhappy customers when things went worng.


          • #6
            Thanks for the responses. That raises another question. I suppose it's impossible to know how much oil the entire system needs?

            Apparently the system doesn't have a leak. The guy I bought the car from had the system evacuated so he could remove the compressor to get better access to rebuild the engine. He never refilled the system.

            I do have a vacuum pump, gauges, and a scale

            The compressor is a gpd and model number is 10p08. This is a tx system.


            • #7
              Unless the system was dis assembled and each component drained, I would just make sure the compressor had the correct amount, it will keep you in the "ball park" .
              I am not failure with those model numbers. what brand is the compressor?


              • #8
                Hmmm? So it did work and just removed to get out of the way. Could be good news for success. Not familiar with that compressor for the moment probably doesn't matter as it WAS working. Oil another question to guess on? Would love to just know what type of oil was used not even a viscosity just the type- a PAG or Ester?

                MetroWest, Boston


                • #9
                  I'm going to flush the system because the guy that rebuilt the engine left the system open for a long time and he lives in a very dusty area, so I'm sure some dust has made its way into the system.

                  Sorry I just noticed I forgot to add an E to the model number. 10p08e. The make is GPD.


                  • #10
                    The sticker on the compressor says pag. I'm planning to just drain the compressor and refill to the correct capacity just in case it didn't have the correct fill from the beginning


                    • #11
                      That's great news. IMO viscosity is less important. How much has to be a guess. If low and working when we get there it would knock some and can add an ounce at a time - guess it whole system probably if zero was in it would be maybe 6oz? No dipstick for A/C oil level or amount it actually makes you have to think!
                      MetroWest, Boston


                      • #12
                        A google search come back that is a Nippondenso compressor it takes 4.5 oz of Pag 46


                        • #13
                          fairly compact compressor with a 3 ear mount and a single 1/2 belt clutch, does that match what you have?
                          GPD is a re-marketer or re-brand of parts made by others. If you need parts, better to find the orignal mfg. name. In this case I am fairly sure it is Nipondenso.
                          Last edited by Cornbinder89; 05-20-2017, 12:20 PM.


                          • #14
                            with the tag calling for PAG, It would have been 134a from the get-go, the A/C may have been added later then when the car was sold, or the aftermarket decided to go with 134a earlier than most of the OEM's did.


                            • #15
                              Yeah, it is a 3 ear and 1/2 inch belt. The owner made me aware that it's not the original compressor. The original compressor was a sanden sd505


                              • #16
                                The OEM user for the nippondenso is Kubota if that helps.


                                • #17
                                  I have no listing of an SD 505 which would be a 5 cyl 5cid compressor according to Sanden's numbering system, the smallest I show is an SD508
                                  edit, I did find a 505, only one, Sanden 9056 so they did make one, again a compact compressor.
                                  Last edited by Cornbinder89; 05-20-2017, 01:04 PM. Reason: More info


                                  • #18
                                    Are you happy with how it's mounted and alignment of the belt? Advise if wrong but don't we have reason to believe this compressor is OK? I wouldn't necessarily make a change unless you find something wrong in hand.

                                    Not mentioned yet is PAG oils (any) are hygroscopic meaning the oil absorbs moisture. Unfortunately if system was left open despite being working just out of the way and not plugged off and let just be back on without a vacuum and some refrigerant even if disabled the oil goes acidic and can eat metal parts from the inside out.

                                    #1. I've never seen that in person nor at the archived site did we figure any way to know for sure moisture is or even can be removed for either desiccant or oils and no convincing known way to do that.

                                    I say vacuum and let it sit in full vacuum (turn the pump off) and let it sit for two days. Run engine for some heat now and then and run vacuum if it creeps up at all but really should stay put indefinitely but I blame some on just hoses on gauges if that long.

                                    Sorry just a thought ahead on getting this to both work and last as long as possible,
                                    MetroWest, Boston


                                    • #19
                                      As far as I know, this compressor was working before the system was evacuated.

                                      So to try to achieve the correct amount of refrigerant, should I fill the system until I see a certain psi reading on the low side?


                                      • #20
                                        OK - Perhaps missed something so if you wish to charge system go for it. Here's a GREAT link I'll find from the site up top that says archives only you too can search for info and procedures. Warning - Lots to read here now.

                                        Before that vacuum again to know it's holding. IDK what you will be using for but you want vacuum to 29.92Hg at sea level can adjust 1 Hg less per 1,000 ft. of elevation and it really should hold once achieved (pump can be off and put back on when it's maxed some take a couple tries - stop and ask if it will not hold. I'll base suggestion on that you are using a gauge set to vacuum pump and tell me/us if thru 12oz small can(s) or a 30lb can you want a scale to watch, do math for weight discharged.

                                        It should be 80F or so for best results. Have a thermos ready in center vent inside car and an real good idea of temps in front of radiator as the temp that are meaningful not just a forecast temp. Can be much hotter over pavement and in sun than you think.

                                        ********* let's see if I can find the links in this case and bear with me this format is new to me also after many years of the same where this forum is really from.

                                        Charging procedures: Link > http://aircondition.com/tech/questio...ing-Procedures < just about print that out when you can and really read it. Any links within that are probably down just read thru it's long and could be longer.

                                        * Priority ONE. Keep air out! From a vacuum with and knowing your equipment have both hoses attached and both knobs open for a while then shut just red high side one finish vacuum thru blue or low side hose.

                                        * All this, engine off. When ready I like to charge what system will take from pressure in source into the vacuum with tank or cans warm not left cool or cold. Now both knobs shut you are reading vacuum. Switch yellow hose to source refrigerant from vacuum pump keeping all air out possible for that switch. Open using liquid into high side till it quits taking more. Low side gauge will show the pressure rise and stop at the static pressure of the temperature of the time when you are doing this. Know how much went in and shut both knobs.

                                        * Start engine and turn on A/C full blast, full blower fan.

                                        * With just this the system should have enough pressure to run and may cycle not knowing controls to shut it down or just stay running.

                                        !! Feel for any heat at high side line off compressor's high and again cool on low side. Quick now see temp at center vent.

                                        * Open blue knob to low side, gas only meaning can up for 10 seconds or so at a time, shut knobs and look for the reading and observe temps at vent again.

                                        When it's blowing cool air not perfect now take you time. Rev engine listen to compressor and if any problems probably should just stop everything and note what was done so far and report that and we'll brain storm some ideas. MAKE NOTES ON WHAT IS IN THE SYSTEM.

                                        It's OK to just stop and disable compressor at this point and ask questions for any problems or pressures not consistent with the procedure link - ASK!

                                        It that links do not work or anything not understood or different equipment than I think you would be using ask before you even begin.

                                        REMEMBER THAT MISTAKES CAN CAUSE DAMAGE - DO NOT RUSH WHEN SOMETHING IS CONFUSING OR SLOW JUST STOP. Shut off compressor to car a must,
                                        MetroWest, Boston