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    Rebuilding AC system

    I've had my 89 Grand Marquis for at least 15 years and long ago had the AC converted to 134. It worked great but in recent years has leaked a bit and I am about to do a full rebuild.

    I bought a new compressor, condenser, all hoses, accumulator/dryer, expansion valve, and cycle switch. Everything except the evaporator in other words.

    I plan to have a shop recover the remaining current refrigerant and do the parts-replacement myself. I can rent a vacuum pump and I have a buddy with gauges and more AC experience than I have, who will help me pump it down and recharge.

    My factory shop manual calls for 48 oz of R-12, and according to "internet" I should be putting in about 75-80% of that weight in R-134. With PAG oil in some amount around 8-10 oz. I am not clear on using the pour-in kind or pressurized kind. I know I need to lube the O-rings with a bit of it.

    It occurred to me that I will need to buy some R134 retro-fit fittings to go on my new accumulator and hose, as they still have the R12 size fittings on them.

    I haven't done an AC job of this magnitude since I installed a Vintage Air kit in my old Mustang back in the 90s. Any Panther-specific advice?

    #2
    if you're using PAG make sure you flush the evaporator and ensure thats whats in the AC compressor. It does not mix with mineral oil. The common conversion oil was ester oil whch does not react badly with mineral, I don't know what PAG does with ester but it does not play nice with any old mineral oil.

    As for the amount, have to know how much is in the compressor to start with. if it tells you, that makes it easy. Just subtract that amount from the 8 ounces and split whatever is left between the drier and the condenser. Pour-in is fine and that will make lubing the O rings easy.

    If you can get a parallel flow condenser it will do better than the original style. If the fan clutch isn't good, replace it. Airflow has a huge effect on all of this.
    86 Lincoln Town Car (Galactica).
    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

    91 Lincoln Mark VII LSC grandpa spec white and cranberry

    1984 Lincoln Continental TurboDiesel - rolls coal

    Originally posted by phayzer5
    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

    Comment


      #3
      I dug through my new parts a bit more. The compressor calls for PAG 100 oil and was shipped with 3 oz in it, so I'll take that into account as you mentioned.

      The condenser I got is parallel-flow. Will take a look at the fan clutch. FWIW, the engine runs cool.

      How should I flush the evaporator? Blow it out with air? Flood it out with PAG oil then blow that out?

      Comment


        #4
        Acetone works well for flushing A/C systems, or they sell a flush. Fill it up and blow it out with compressed a couple or three times.
        Not sure of the cost of renting a vacuum pump. I purchased one on Amazon for $60 a couple years back and have used the heck out of it since. Might consider buying one instead of renting one, depending on cost.
        1990 Country Squire - weekend cruiser, next project
        1988 Crown Vic LTD Wagon - waiting in the wings

        GMN Box Panther History
        Box Panther Horsepower and Torque Ratings
        Box Panther Production Numbers

        Comment


          #5
          It's free to borrow one at O'Reillys, with a $170 deposit. I didn't realize how shockingly cheap they are on Amazon though, wow.

          Comment


            #6
            Do try to get a better one. There are some real "cheapies" there as in other places!
            What I Own: 1993 Mercury Grand Marquis GS
            What I Help Maintain: 1996 CV / 1988 CV / 1988 Tempo

            Comment


              #7
              If its an air-powered vac pump that won't do it. Need an electric. The other trick is the vac oil needs to be changed once in a while or it will not pull a properly hard vacuum. real HVAC guys use a micron gauge to verify it. Us hacks just use the manifold gauges and make sure it pulls and holds. Run it as long as you like but not less than 20 minutes.

              and yeah they make AC flush but its just solvent in a can. Acetone and compressed air will do it, just make sure its all flushed out and blow air through it for a while to make sure its all gone. There usually won't be much in the evaporator but may as well start clean. I'd flush it backwards just for the heck of it, so acetone and air in on the connection that normally goes to the drier. Use a hose stuck onto the inlet to direct whatever comes out into a jug so it doesn't get all over. Can use the old liquid line if you're replacing it anyway. The orifice tube needs to be out for this but you'll be changing that anyway.
              86 Lincoln Town Car (Galactica).
              5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

              91 Lincoln Mark VII LSC grandpa spec white and cranberry

              1984 Lincoln Continental TurboDiesel - rolls coal

              Originally posted by phayzer5
              I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

              Comment


                #8
                Thanks for the advice guys. I got the job mostly done.

                I had the old refrigerant evacuated at a shop. They got it done quickly and just charged me $40. The manager also gave me some advice on the repair, including the spray can flush mentioned above. He also told me about another spray can that you shoot up the condensate drain to clean out the evaporator fins/housing. I haven't done that part yet but plan to.

                As far as the repair went... a couple things bit me in the ass.

                The suction line between the compressor and dryer was an issue I saw coming and tried to deal with. The original hose has a metal U-bend in the middle. All the replacements I've seen do not have this bend, you just have to twist the hose into a loop. I didn't like the routing so I planned to have a parts store modify it to add the U-bend. Drove all over town and couldn't get that done in an efficient timeframe so I ended up living with the routing. It wasn't quite as bad as I expected but still not optimum.

                The compressor, condenser, dryer, and all the hoses came with O-rings. I also bought a little pack of O-rings to begin with, just in case. And yet I still came up short. The two fat O-rings between the compressor manifold and the discharge line mounting block were not included with any of it. So I had to order the $16 full kit and wait a day for it just to get those two rings.

                I initially borrowed loaner gauges from O'reilly's, in addition to the vacuum pump. Then had to go get a different pump because the first one had a problem (call that Tool Failure #1).

                Then when I pumped the system down I could only get to 21" Hg. Talked it over with my buddy and decided to try his digital gauges. It pumped right down to 29" and held tight. We chalked it up to an inaccurate gauge on the loaner manifold (Tool Failure #2).

                Started charging. Got about a half a can into the system and BOOM. The liquid line blew off at the evaporator end. Fine mist of oil and 134 into the ozone, dammit. Shot the orifice tube right out. I cleaned it all up and looked things over, and either I didn't have the line fully clicked on, or the spring retainer in the hose was faulty. Added a little oil to (hopefully) compensate for the mist and put it back together.

                Pumped it down again. Put two cans of freon in and all going well. Vents blowing pretty cold. I tapped the third can of freon and hooked it up. Purged the yellow hose and nothing really came out. Looked at the can and there was a tiny bit of mist leaking out of the valve. Fiddled with it and got the mist stopped but could not get the can to flow. Can tap stuck or broke. Tool Failure #3.

                And of course when I removed the QD fittings, one of my schrader valves leaked a little and I had to find the tool to tighten it up. The dust cap seemed to be enough to stop the leak in the meantime.

                Where I left it last night, I had 38.7 psi on the low side and 116 psi on the high side, with unseasonably cool ambient temp in the high 70's. I drove it around the neighborhood, and even with the low charge, it was blowing about 47 at the vent. I'm theoretically a can low on freon, which I hope to remedy tonight.

                Lessons learned:
                Buy the full O-ring kit and prepare to have many extras
                Plan way ahead if you want to add the U-bend to the suction line
                Don't trust the tools till you can trust them
                Visually ensure the spring retainers are engaged when you click the lines (it required a mirror to see the one that blew, in my case)
                Wear safety glasses (I was, when that line blew... just another reminder)​
                Check the schrader valves before you do anything

                Comment


                  #9
                  Sounds like it fought you the whole time. Hope the final charge goes okay.

                  Here's the cheapo vacuum pump I have been using. It works great. Pulls 29-30 inches of vacuum, no problem. https://www.amazon.com/Kozyvacu-TA35...Y2hfbXRm&psc=1
                  1990 Country Squire - weekend cruiser, next project
                  1988 Crown Vic LTD Wagon - waiting in the wings

                  GMN Box Panther History
                  Box Panther Horsepower and Torque Ratings
                  Box Panther Production Numbers

                  Comment


                    #10
                    I prefer the dual stage - for performance reasons and longevity but hey - what ever works!!!
                    What I Own: 1993 Mercury Grand Marquis GS
                    What I Help Maintain: 1996 CV / 1988 CV / 1988 Tempo

                    Comment


                      #11
                      The garter springs can be a bit of a chore to get fully locked on. I've had them pop loose before if not 1000% sure it clicked.

                      have also had issues with can taps, the new self-sealer cans are kinda funky and the adapters aren't so awesome. Sometimes it just doesn't feed or feeds really really slowly for unclear reasons. I'm tempted to get one of those side-tap things that just clamps onto the can and punches a hole through the body rather than dealing with the fitting on top.
                      86 Lincoln Town Car (Galactica).
                      5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                      91 Lincoln Mark VII LSC grandpa spec white and cranberry

                      1984 Lincoln Continental TurboDiesel - rolls coal

                      Originally posted by phayzer5
                      I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                      Comment


                        #12
                        I believe the slow charge (especially on consumer equipment) is by design for system safety. They probably assume most of us don't know what we are doing.
                        What I Own: 1993 Mercury Grand Marquis GS
                        What I Help Maintain: 1996 CV / 1988 CV / 1988 Tempo

                        Comment


                          #13
                          Its not really safer to undercharge though. It won't carry the oil properly and that can kill the compressor. The short-cycling isn't good for the clutch either.
                          86 Lincoln Town Car (Galactica).
                          5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                          91 Lincoln Mark VII LSC grandpa spec white and cranberry

                          1984 Lincoln Continental TurboDiesel - rolls coal

                          Originally posted by phayzer5
                          I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                          Comment


                            #14
                            Originally posted by gadget73 View Post
                            Its not really safer to undercharge though. It won't carry the oil properly and that can kill the compressor. The short-cycling isn't good for the clutch either.
                            I was not referring to serious undercharge that causes damage - just not enough for full performance.
                            What I Own: 1993 Mercury Grand Marquis GS
                            What I Help Maintain: 1996 CV / 1988 CV / 1988 Tempo

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