wanted: someone who can work on a R12 system in College Station area.

Discussion in '6.9L IH & 7.3L IDI Diesels' started by towcat, May 7, 2018.

  1. towcat

    towcat Administrator Staff Member

    Posts:
    18,152
    Likes Received:
    1,343
    Joined:
    Jun 24, 2004
    Location:
    SantaClara,Ca/Hamilton,TX
    Just like the title says. or someone who knows how to do R134 conversions PROPERLY.
    lmk.
    this is a paying job. but be reasonable.
     
  2. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

    Posts:
    4,828
    Likes Received:
    2,727
    Joined:
    Jul 27, 2015
    Location:
    Bulverde, Texas
    When do you need it done? What is it on? I can’t fit much more work in the near future because my schedule already very full, but I know a couple good ac guys around here that could.
     
  3. MTKirk

    MTKirk Full Access Member

    Posts:
    405
    Likes Received:
    24
    Joined:
    Nov 29, 2015
    Location:
    Billings, MT
    How about you? Get system evacuated (should be almost free for r-12 recovered or around $40). Open system to air (yes I said open to air) maybe add a few ozs of mineral oil if you think a lot has leaked out, fill with recommended amount of envirosafe and voila! you're nice and cool . https://www.amazon.com/Enviro-Safe-...qid=1525737722&sr=8-5&keywords=envirosafe+r12
     
    Last edited: May 8, 2018
  4. towcat

    towcat Administrator Staff Member

    Posts:
    18,152
    Likes Received:
    1,343
    Joined:
    Jun 24, 2004
    Location:
    SantaClara,Ca/Hamilton,TX
    the owner/operator of the truck is in danger of "melting" in the heat, so it will need to be done sooner than later. i won't be in TX until later this year, so I can do anything about it asap. therefore, I'm farming out the job. pm me their contact info. thanks !!!!
     
    Trevtron likes this.
  5. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

    Posts:
    4,828
    Likes Received:
    2,727
    Joined:
    Jul 27, 2015
    Location:
    Bulverde, Texas
    Pm sent
     
    Trevtron and towcat like this.
  6. DrCharles

    DrCharles Full Access Member

    Posts:
    451
    Likes Received:
    203
    Joined:
    Dec 18, 2017
    Location:
    West Plains, MO
    I would NOT open the system to air, and have never understood why on earth the manufacturer says so. I think it's because the average backyard tinkerer doesn't have a vacuum pump and they don't want to lose sales by recommending it be done correctly with the right tools...

    Why admit humid air that will have to be dried by your desiccant, and make high-side pressures too high because air does not "refrigerate"? With a propane-butane mix, which is what Envirosafe is, evacuate the system and remove the moisture as with any quality job! Besides do you really want a system under pressure with propane, butane, oil AND air... the flammability of a few ounces of hydrocarbons don't bother me per se. I'm running it in my truck right now and it's working great. R-134a wasn't as impressive, and had higher high-side pressures, due to the old serpentine tube & fin condenser. For good really-hot-weather performance it'll need a new parallel-flow condenser (which means custom hoses to & from it), or a pusher fan turned on when the compressor is.

    Too bad Towcat's not closer to southern MO, I'd help him do it for pizza and beer ;) I even have a 609 card.

    ps a viola is a stringed instrument like a large violin. I think you meant voilà :D
     
    Thatoneguy and Macrobb like this.
  7. 79jasper

    79jasper Chickenhawk

    Age:
    26
    Posts:
    15,630
    Likes Received:
    1,087
    Joined:
    Oct 13, 2012
    Location:
    Collinsville, Oklahoma
    I think its because you need "less weight" to equal the required pressures.
    If you vacuumed, you would have to put more in before you reached the correct pressures.
    Make sense?
    No? Okay, back under me rock....

    Sent from my SM-G892A using Tapatalk
     
    Thatoneguy and Macrobb like this.
  8. DrCharles

    DrCharles Full Access Member

    Posts:
    451
    Likes Received:
    203
    Joined:
    Dec 18, 2017
    Location:
    West Plains, MO
    No... but you don't have to hide under a rock either. :D

    HC refrigerant does need only about 35-40% by weight of the original R-12 amount. My '93 called for 44 oz. of R-12, so 16 oz. of Envirosafe is a full charge. Notice that the Envirosafe can is only 6 oz by weight so 2.5 cans is still about right. If there's air in the system it takes up room that should be used for the refrigerant (when it expands through the orifice it absorbs a trivial amount of heat compared to the liquid). I do wonder if they wanted to "cheat" so the pressures are different with the air inside - but that would be a really crappy design.

    Our trucks have a CCOT system (cycling clutch, orifice tube) and the evaporator is supposed to be flooded. That's why that big black can, which is an accumulator, is on the low side after the evaporator - to provide a place for the refrigerant to boil back into vapor so it doesn't liquid-slug the compressor intake.

    The pressure of any refrigerant is directly related to its temperature and each one has a unique pressure-temp curve. A mix of propane and butane (roughly 70/30) makes the low-side pressure just about the same as R-12 without an excessive high-side pressure and can carry any type of oil, which is what lubes the compressor. R-134a needs a higher pressure than R-12 (a few psi) to keep the evaporator above freezing AND needs more condenser to get rid of the extracted heat - which means more pressure on the high side. And is absolutely incompatible with the mineral oil the R-12 systems used.

    Anyway there's a lot to learn about refrigeration systems and this is just scratching the surface. I don't pretend to know it all (I was an EE not an ME) but I've been doing my own repairs for a long time and do a lot of reading, so I have a good idea of what works and what doesn't.
     
    Macrobb, KZF250 and 79jasper like this.
  9. 79jasper

    79jasper Chickenhawk

    Age:
    26
    Posts:
    15,630
    Likes Received:
    1,087
    Joined:
    Oct 13, 2012
    Location:
    Collinsville, Oklahoma
    Yep, same here. Lol
    That was my thought, "cheating the pressures."
    When my 94 was charged to where it was cooling the most, the compressor stayed on full time when the ac was on. Once it leaked out some (found out the high side port leaked after charging it so just ran it with the cap tight lol) it would cycle.

    Sent from my SM-G892A using Tapatalk
     
  10. towcat

    towcat Administrator Staff Member

    Posts:
    18,152
    Likes Received:
    1,343
    Joined:
    Jun 24, 2004
    Location:
    SantaClara,Ca/Hamilton,TX
    thanks.
    I forwarded the info to her :D
     
    Thewespaul likes this.
  11. MTKirk

    MTKirk Full Access Member

    Posts:
    405
    Likes Received:
    24
    Joined:
    Nov 29, 2015
    Location:
    Billings, MT

    I hear ya, I have a vacuum pump and gauges, and the first couple of envirosafe jobs I did I pulled and held a vacuum first, as you'd do with any other refrigerant. I blew an o-ring on my benz and lost everything and thought "what the hell, I'll try it without pulling a vacuum first" the result was about 3 degrees COOLER air. I have no idea why, it just is. The car has been working this way for 2 years now on the same charge with an antiquated system that wouldn't hold r134a for more than a few weeks.
     
  12. DrCharles

    DrCharles Full Access Member

    Posts:
    451
    Likes Received:
    203
    Joined:
    Dec 18, 2017
    Location:
    West Plains, MO
    My theory is that the first time your MB was overcharged and the high pressure blew the o-ring. HC's only have a few oz. between under- and over-charged. I always start low, go slow and watch the gauges patiently :)
     
  13. chillman88

    chillman88 Supporting Member Supporting Member

    Posts:
    1,551
    Likes Received:
    807
    Joined:
    Feb 22, 2017
    Location:
    Central NY
    Is this why the cheap home conversions seem to die a quick death? I've never done it, but I've heard of it.
     
  14. DrCharles

    DrCharles Full Access Member

    Posts:
    451
    Likes Received:
    203
    Joined:
    Dec 18, 2017
    Location:
    West Plains, MO
    yep... R-134a does not carry mineral oil around the system so the (sumpless) compressor dies from lack of lubrication.

    Also, the quickie Death Kits don't even recommend removing the old oil. They just throw a few ounces of the correct oil in, and hope the old stuff sits in a quiet corner not causing trouble. Sometimes it does.
     
    chillman88 and Trevtron like this.
  15. david85

    david85 Full Access Member

    Posts:
    3,955
    Likes Received:
    227
    Joined:
    Feb 21, 2008
    Location:
    Campbell River, B.C.
    The old oil often leaks out with the refrigerant, so there probably isn't much left in there. At least, that's the hope. 134a also can't be contained by the R12 hoses due to smaller molecules. The old seals are also much more leak prone for the same reason. I'm not saying a 134a conversion can't be done properly, but I determined it wasn't worth my while to even try.

    I forked out for all new parts when I re-did mine. New compressor (not reman), hoses, parallel cross flow condenser and so on. I also forked out for a vacuum pump and gauges. There are enough AC equipped vehicles in my family to make it worth my while. For the cost of one, maybe two AC service jobs at a professional shop, I had all the tools to do it myself.

    After all that, I charged up with HC-12 and never looked back. It's legal, works great, and I don't need a license so I can do as I please without any "interference". Heck, I'd even be tempted to try straight propane like one guy did a while back. Not likely now that everything works fine, but still, I can't help but wonder how well it could be made to work.
     
    Last edited: May 9, 2018
    chillman88 and 79jasper like this.

Share This Page