How to rebuild an ac setup?

Discussion in 'OEM and Custom Interiors' started by Doughnuts, May 6, 2018.

  1. Doughnuts

    Doughnuts Newbie

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    Hello all!

    I'm curious on what it would take for a diy'er to put in an new air conditioning setup . So let me preface this first .

    Probably the last warm day of 2017, I was running around with my ac on and the compressor decided to kick the bucket and lock up on me . I kinda figured it was on it's way out with dumping r134 in an r12 system that's 27 years old. And summer is now upon us in this humid Missouri climate, and I have a few road trips coming up and I'd really prefer to have it back working again .

    So my questions are this, is there a way just to free up the compressor the cheap and dirty way? Or would I just be better off rebuilding it? And if rebuilding it is the answer, then what would that entail? I can pick up a Murray ac oem replacement for like 170 Bucks but what else would I need and what would I have to do, to do it myself? Or would it be more economical to have a shop do it all? As of now I was planning on having a shop drain the system, then I would replace the compressor and what ever else I might need and then pump some new freon in. I've also heard that one should have the system flushed before putting in anything new?

    Unfortunately ac is a bit out of my wheelhouse . So any insight would greatly be appreciated.

    It's a 1991 c1500 350
     
  2. deadbeat

    deadbeat Centurion Crew Cab

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    I redid it all on my 1997 last year. I bought the manifolds and vaccum pump for about 120 bucks, new compressor, drier, and orfice tube. The lines on the condensor stripped so I had to buy a new condensor and lines. It might have been cheaper to pay a shop if they actually do it right, but looking at the orfice I pulled I am glad I know it was all done right because it wouldn't have lasted long if I had just put on a compressor and not changed the other parts. Yeah, it was a bad day all along, the new drier I bought stripped out when I removed the line from it so I ended up buying 2 of them.
     
  3. someotherguy

    someotherguy I'm Awesome

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    Yeah...the compressor locking up is a bad sign; very likely the system is contaminated. You don't want to put new parts on there just to have crud in the system kill them early. In fact, many (probably most) compressors they won't honor the warranty unless you also show that you bought a new accumulator (dryer), orifice tube (aka expansion tube on your R12 system), and a can of flush.

    You might also consider buying a new condenser as it's difficult to effectively clean one out. Cost you about $60-$75 more. New lines/manifold might be a good idea too; the set for your truck runs about $35-$60 depending on where you find it.

    Keep in mind your 1991 is unique in a few instances on the A/C parts; this was a switchover year for the orifice tube to be located in the lower line coming out of the condenser instead of the opposite end of the line at the evaporator...so any parts you might order - the evaporator, condenser, manifold/line set and lower line should be checked closely to be sure they are ordered correctly and match your parts when you compare them.

    Any remaining parts in the system - evaporator core (the part inside the cab hidden away in the ductwork box, fittings poke out of the firewall), any lines you leave in place, need to be flushed thoroughly with A/C cleaning solvent. Push that stuff through with compressed air to be sure it goes through and dries out. Do this with the system fully disassembled so it doesn't go into places you don't need it to, like the compressor and accumulator.

    Once everything is assembled you'll need a vacuum pump to pull it down for a nice long time to get any air and moisture out of the system, then shut down the pump and see if it holds vacuum a long time as well, to be sure you don't have any leaks, before charging it up. Correctly vacuuming it down and charging it up with oil & refrigerant is honestly best left to a specialist. You -CAN- DIY it, it's just tricky to get it just right when you're not experienced.

    Richard
     
  4. c1500deathtrap

    c1500deathtrap I'm Awesome

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    You put r134 in an r12 system? If i read that right you have a gummed up mess inside now. Toss the compressor, get a new drier, orifice tube, then clean and flush the whole thing. On assembly, make sure to use the r134 compatible o-rings. For the oil use ester based.When it's all hooked up, evacuate the system using a vac pump (autozone will rent you one) let it hold vacum to check for leaks, then fill er up. Like someotherguy said a new condenser ain't a bad idea.
     
  5. Blackwater

    Blackwater Engineering Geinus

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    My compressor locked up on me as well. I replaced the dryer orifice tube. Flushed the heat exchanger but replaced the evaporator in the grill because I realized when changing the orifice tube that the truck had been in a front end collision. 3years and still working.


    Sent from my iPhone using Tapatalk
     
  6. outlawten5

    outlawten5 Newbie

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    Blackwater, where did you source your parts? Having a hard time finding quality stuff.
     
  7. Snowmanii

    Snowmanii Newbie

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    I can't get one of the lines off from the condenser to the evaporator. I ended up cutting the condenser side off and buying a new condenser. Now the evap side wont come off. I dont want to have to tear into the inside too. Any experience with these lines?
     
  8. magimerlin

    magimerlin I'm Awesome

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    Heat can be your friend on those lines. I've had to use heat on many a old a/c systems through out my mechanic years.. oh, and long handled wrenches...

    Break it loose, tighten a little bit, loosen it more, tight a bit... kinda like tje motion you use when using a tap and die set.

    Sent from my SAMSUNG-SM-G891A using Tapatalk
     

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