AC Learn and fix

Discussion in 'Audio + Electronics' started by Eveready, May 19, 2020.

  1. Eveready

    Eveready I'm Awesome

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    After polluting @phatphuck 's thread with my AC issue which is somewhat similar to his, I have decided to do the right thing and post my own. My AC leaked down after last season and I hadn't bothered to look at it until it started warming up around here. This year Spring has been longer than usual in NC, a couple of weeks. Usually it takes about a half day to switch from freezing your ass off to burning hot.

    When I started to look at the AC it turned out that the high side valve cap had broken off in the fitting leaving a little dome of pastic that I thought was going to be difficult to remove . I rounded up some tools and got after it this afternoon. It took about 10 seconds to insert the end of a knife blade into the plastic and back the plug out . I have new plugs on order. Once those arrive I will look into charging the system. What I think happened is that the plug was too tight on the schrader causing it to slowly leak down . The good news is I was able to get a little hiss out of it after clearing the fitting of broken plastic so the system may just take a charge instead of needing to start over. Will document what I end up doing as I do NOT want to face a NC Summer without AC.

     
  2. PlayingWithTBI

    PlayingWithTBI Desert Old Guy

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    Glad you got it out. :peace: The cap shouldn't be able to hit the schrader valve but, who knows?
     
  3. Eveready

    Eveready I'm Awesome

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    Couldn't tell. It was pretty far in but screwed out pretty easily. I'm just glad there was some pressure. As soon as the caps show up the next thing will be to get out the guages and see what is going on. I have been watching the usual YouTube videos and making myself a check list so that I don't do something stupid like opening the wrong valve and trying to charge the high side.

    I will consider it a victory if I can get a season out of it without replacing more parts. I really need to replace the blower motor but you know what a joy that will be. It works on all speeds but does whine a little on startup. I may be able to put that one off a while. In the Summer around here it usually stays on high anyway.
     
  4. PlayingWithTBI

    PlayingWithTBI Desert Old Guy

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    Yeah, last week we already were in the 100*+. I checked mine and all's well since I redid the system sometime last spring IIRC. I had to turn the fan down to medium it was blowing too cold.

    The most common cause of leaks is the compressor front seal. Take a look at the compressor and pulley, if you see any oil or wet spots, there's your leak. Time for a new compressor, don't even bother trying the replace the seal. IMO the inner bearing is sloppy enough to ruin the seal, which means, the new seal won't last very long.
     
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  5. Eveready

    Eveready I'm Awesome

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    Thanks I will take a close look at it . I am hoping it was the valve. The system was retrofitted right before I bought the truck and checked out OK then but that has been a couple of years. I only ran it a little last year before it started getting warm on me and I don't use the truck a lot anyway. I decided that this is the year to sort it out and got gauges and a vacuum pump and started studying up. My old van tends to leak down over the Winter and I didn't want to pay to charge up two vehicles. I keep telling myself I'm not too old to learn how to fix something.
     
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  6. R422b

    R422b OBS Enthusiast

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    I have a few tips on charging automotive ac.
    As always there is more than one way to skin a cat but this is the method that has been working well for me.
    Many people will use guages and guages have there place but there is no chart showing what the pressures should be for any vehicle ac which is why the study guide for the automotive refrigerant licensing condemns small cans and guages as incorrect and not acceptable.
    According to them the only way to charge an MVAC (motor vehicle ac) is with a multiple thousand dollar machine that sits in a shop and is dedicated to that purpose.
    I dont service vehicles in a shop so that option besides being expensive would just not work and for the diy'er it wont work either.
    So guages are a very handy tool but the only thing I will use them for is diagnosis. For charging there is a better way.
    First if at all possible buy a cheap refrigerant scale off of Ebay or some place. Then buy a 30lb cylinder of refrigerant (requires a license but the license is 20 dollars and the study guide has a lot of good information on servicing MVAC systems)
    Then you will need 2 automotive to 1/4 inch flare adapters off of Ebay/Amazon, a 1/4 inch flare T, 2 refrigerant hoses with built in ball valves and a vaccum pump (harbor freight has one that works for under $100)
    If you must go cheap just get a low side adapter, 1 hose with ball valve and a vaccum pump.
    Now assuming that the system is empty (no venting of refrigerant allowed) connect your adapters to the ports or just the low side port if that is what you have. Then connect the hoses from the adapters to the vacuum pump using the T if you have 2 hoses.
    Now if your system has a leak that you have not fixed then you should not pull a vaccum so assuming that you have repaired the leaks run the vaccuum pump until the sound has changed and no air is coming out of the discharge (the proper way to tell if evacuation is complete is using a micron guage but the cost is too high for most diy) when you decide that enough air and moisture is removed from the system close both ball valves and disconnect the low side quickly connecting it to the refrigerant jug that you should have sitting valve up on the scale ready. Now zero out the scale and open the valve on the tank and then the valve in the hose. Now wait until the pressure starts to equalize watching the scale to make shure that you dont over shoot the required weight.
    Now most likely the pressure will equalize long before you reach full charge so you will have to start the vehicle and turn on the ac to use the compressor to suck the rest in. I try to stop within 0.1 oz of the required weight. When the charge is weighed in turn off the ball valve and then the tank valve followed by removing the adapter from the port on the car.

    If you can't afford the 30 pound tank of refrigerant and the scale just use the low side adapter and hose with a 12 oz can with a can adapter. Figure out how many cans and fractions of cans it will take and add that much as best as you can estimate.


    The main thing is add refrigerant by weight not pressure and if possible pull a vaccum first to remove moisture and air.

    Sorry for the long rambling post.
    I am a heating air conditioning and refrigeration technician who dabbles in MVAC


    Sent from my SM-J260A using Tapatalk
     
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  7. Bear 77

    Bear 77 Newbie

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    Good information!


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  8. Eveready

    Eveready I'm Awesome

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    Thanks @R422b Great post and lots of good info. That one goes in the infamous "truck" file. I already have a set of hoses so likely will charge with that set and see if I can get any cool out of it. If I have to start over with an empty system I will do it your way. I like the idea of geting a cannister instead of the cans as I have several cars to keep up.

    Will report when I see what is going on with it. New caps on order right now and it is cool and wet outside here.
     
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  9. Eveready

    Eveready I'm Awesome

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    Finally got the gauges on the truck today and no charge at all left in the system. I swear I got a little hiss out of it when I checked last week but if I did that was the last gasp. Next step I will pull a vac on it and see how long it holds if at all. I still think that weird schrader cap had something to do with it. If I can get it to hold a vac I will charge it and see what is what . If no vac, some tracer and go from there. There is no sign of seal leakage at the compressor and it hasn't been all that long since the system worked. Will update when I know more.
     
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  10. R422b

    R422b OBS Enthusiast

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    If you have access to nitrogen or co2 (not compressed air) then do a pressure check first.
    The most pressure differential you can get with vaccum is less than 14.7psi and it is in the opposite direction that the refrigerant will be trying to get out so if there is some crud on the leaking spot it could Get sucked into the leak and male it appear to hold but then still leak under pressure.
    The main purpose of pulling a vacuum is to remove moisture.

    Sent from my SM-J260A using Tapatalk
     
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