1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

A/C System Leaks

Discussion in 'Tech Discussion' started by Old60Driver, Jun 19, 2021.

  1. Old60Driver

    Old60Driver 1983 K20 Silverado

    Posts:
    119
    Likes Received:
    126
    Joined:
    May 17, 2020
    Location:
    Houston
    First Name:
    Michael
    Truck Year:
    1983
    Truck Model:
    K20 Silverado
    Engine Size:
    350
    Okay folks, I did a stupid. I knew I was doing it wrong at the time too, but impatience got the better of me...

    So, the '83 came with factory air, and I decided, at the behest of my better half to see if it was serviceable. Here's what I did:

    1. Checked for pressure. Zero. Not a pip...
    2. Swapped out the accumulator. Old one has a solidified block in there??
    3. Swapped out the accumulator tube
    4. Swapped out the orfice tube. Old one was pretty nasty
    5. Changed out o-rings
    6. Removed A/C compressor and tried to empty it. There was nothing in there. Added about an ounce and a half of ester oil to the compressor, and reinstalled. DID NOT change out the compressor connection seals. Didn't want to wait for them to come in. Impatience failure number one.
    7. Installed the R12 to 134A service ports.
    8. Did NOT put a vacuum pump on the system. Impatience failure number two.
    9. Put a charge of PAG oil in system, followed by 4 cans of 134A.
    10. SHE LIVES!
    11. Compressor started cycling once a second. Then stayed on longer and longer, until she was running just fine!
    12. Let her stabilize for a while, all seemed well
    13. Took the wife on a little cruise, and she blew nice and cold. I had to turn it down in fact, and that's saying something, as it's hotter than heck here in Houston these days at 2 in the afternoon.
    Success right? Nope. As I said, I should have vacuum tested they system, but they didn't have any vacuum pumps at my local parts house for rent, and Harbor Freight was out of them. I figured, how bad can it leak?

    Well, I'll tell ya. About 2 hours was all it took of it just sitting there for the compressor to not engage. I'm guessing due to low pressure. But damn, it would have to leak 2 whole cans out in two hours for that to be the reason. Still...

    I haven't dug into it yet this morning, but I am so damned mad at myself right now. I'm not usually a guy to cut corners. But I did. And it bit me in the A$$. It was only an hour or so, and about 50$ worth of freon, but still, I'm kicking my self for lost time and money. LOL

    I'm thinking the compressor, condenser, or evaporator is leaking, but I won't be able to tell until I get the vacuum pump on her.

    OR my low pressure switch crapped out on me.

    Either way, I'll let y'all know what I find.

    No more corner cuttin' for me...
     
  2. QBuff02

    QBuff02 I like Big Blocks and I cannot lie Supporting Member

    Posts:
    714
    Likes Received:
    1,154
    Joined:
    Feb 28, 2017
    Location:
    Central IL
    First Name:
    Quincy
    Truck Year:
    1982
    Truck Model:
    K30
    Engine Size:
    454
    It could be any number of things or places. mix up a bottle of soap and water and start spraying down lines and connections. And even though you put a couple cans of DIY charge in, the system could still be low. However, a leak big enough (if it truly did leak out that fast) will be very easily spotted. Did you put the caps back on the Schrader valves after you filled the system and got it operating? Those caps aren't just for keeping the ports clean, they are actually the main seal for the fill/test ports and most people don't realize that. It could be simply leaking from the Schrader valves. Also, when you put the orings in did you coat them with the oil you put in the system? I've always been taught that you want to oil the seals so the connection isn't "dry" but i'd bet if you start soaping the lines, you'll find that you have one that is leaking. I'd add enough into the system to get the compressor cycling again then shut the truck off and I bet you will hear the leak before you find it. Also, air in the system can cause your pressures to be higher than normal which will also throw the system off. Part of why you're supposed to pull a vacuum on it (as you know) to remove contaminants, determine if there are leaks, and also pull all the air out. If you suspect the switch is bad, put a jumper wire on it and if the compressor cycles then the system is either low (which you suspect) or the switch has failed. Just a few ideas for you and things to check.
     
  3. Old60Driver

    Old60Driver 1983 K20 Silverado

    Posts:
    119
    Likes Received:
    126
    Joined:
    May 17, 2020
    Location:
    Houston
    First Name:
    Michael
    Truck Year:
    1983
    Truck Model:
    K20 Silverado
    Engine Size:
    350
    Thanks for the reply QBuff

    Yes sir, caps secured.

    No sir, that is something I DIDN'T do. I'll be looking at those connections again.

    Didn't think about air being in the system. Doh!! Looking for a vacuum pump now, and will advise after I redo everything I should have done yesterday! LOL

    That being said, once I pull the vacuum, and get that mess sorted, I'll need to reintroduce oil, correct? I used a pressurized PAG oil charge, followed by 4 cans of straight 134A. I'm assuming I'll need to repeat the process after I vacuum test the system, right?

    Thanks again!
     
    Snoots likes this.
  4. QBuff02

    QBuff02 I like Big Blocks and I cannot lie Supporting Member

    Posts:
    714
    Likes Received:
    1,154
    Joined:
    Feb 28, 2017
    Location:
    Central IL
    First Name:
    Quincy
    Truck Year:
    1982
    Truck Model:
    K30
    Engine Size:
    454


    Most vacuums will pull a small amount of oil out of the system when drawn down. and although it isn't always the case, rule of thumb is if it pulls a bunch of oil out of the system it generally had too much oil to begin with. If you have a way to measure the oil pulled out by vacuum, inject that much back in. so if it pulls 2 ounces out, put 2 ounces in. And always add oil back in when changing components or lines. Most "good" systems I see, will only pull a couple ounces out at most during recovery. As a rule of thumb I generally put a solid 2 ounces in when I recharge, but I also use the oil with leak detector in it so it's more of future insurance and ease of locating leaks that the bubble method won't find when the need arises. Some manufacturers will say you're actually injecting contaminants in by using leak detection dye and some manufacturers will complain if they know, but for our "old" stuff and 90% of what we do, dye in the oil is your friend. If you have a vacuum on the system there isn't a need for a pressurized oil charge. so long as you have the means to hook up the oil and simply open your fitting and it will suck the oil charge right in. I'll pull a vacuum for a good 20-30 minutes or until the gauges are long steady in vacuum and then close everything off and wait 15-20 minutes and monitor the gauges, if they move then you still have a leak. That's why I always try to find the leak while there's still a little pressure in the system before pulling the vacuum to recharge. Find, fix, suck, charge.
     
    Poppy 87 likes this.
  5. Doppleganger

    Doppleganger Supporting Member Supporting Member

    Posts:
    3,247
    Likes Received:
    9,641
    Joined:
    May 24, 2019
    Location:
    OH-MI: Just like it sounds
    First Name:
    Chris
    Truck Year:
    1985
    Truck Model:
    K20
    Engine Size:
    5.7
    Sounds like me and my ex wife.....but I digress.

    Not having it vac'd is where I would start to point fingers. If there was alot of moisture in the system (and Houston isn't exactly Vegas), that accumulator/drier would fill right quick, plus it makes it more difficult to 'squeeze' the heat out (which is what a compressor does) with any water and air complicating things.

    Did you put oil in the drier as well? IIRC, an 8oz bottle of PAG.....4 in the compressor and 4 into the drier, oiling every O ring as well.

    None of it is difficult....just particular.
     
  6. CRM

    CRM Full Access Member

    Age:
    65
    Posts:
    725
    Likes Received:
    1,325
    Joined:
    Jun 6, 2016
    Location:
    Pasco, Washington
    First Name:
    Casey
    Truck Year:
    1977
    Truck Model:
    C10
    Engine Size:
    250 CI
    Being an air conditioning service tech for 41 years now let me point out a few things.
    If you're using a vacuum pump that's capable of pulling oil out of the system, your vacuum pump is way too big.
    Access caps are not a main seal. The schraeder valves and O Rings are. The caps are there to keep dirt out and act as a backup should the schraeders start leaking.
    Be very careful with how much oil you put in. Too much is just as bad as too little.
    Air (and the moisture that's in it) can do several negative things in a system. Air drives up the high side pressure and less heat is ejected thru the condensor coil. Moisture can freeze in the metering orifice and block Freon flow. Moisture can also mix with the oil and cause acid to form.
    A vacuum should be pulled for at least 30 minutes. Typically you'll know when the system is entirely vacuumed because when you close the gauges the sound the vacuum pump makes does not change. If it does then you either have a leak or it hasn't removed all the contaminants yet. The system should sit in a vacuum for at least an hour to confirm no leaks, unless you using a micron gauge, in which case you'll know in under 10 minutes.
    Soap and water are a good way to find leaks as long as it's more soap than water. If the leaks are in the evap coil or condensor coil then it'll be harder to find with soap. If you can get your hands on a sniffer used to locate refrigerant leaks that's the way to go.
     
    Last edited: Jun 19, 2021
  7. louu

    louu Full Access Member

    Posts:
    122
    Likes Received:
    117
    Joined:
    Sep 19, 2020
    Location:
    South NJ
    First Name:
    Lou
    Truck Year:
    1986
    Truck Model:
    C30
    Engine Size:
    454 baby!
    It's the rubber hose connections on the line set. Take them to a hose shop and they will replace and properly crimp on the hoses.
     
  8. Dave M

    Dave M Full Access Member

    Posts:
    401
    Likes Received:
    824
    Joined:
    Jul 30, 2019
    Location:
    Australia
    First Name:
    Dave
    Truck Year:
    1976
    Truck Model:
    C10
    Engine Size:
    454
    Spot on Casey, we are both in the same trade ! To add, the compressor apparentley had no oil to start with, and l would also be concerned for the condition of the compressor and shaft seal. I'm amazed you guys over there in the US can buy refrigerant so easily, when over here, the purchase and use of refrigerant gas is highly regulated. Apparently some asshole complained about the size of a hole in the asszone layer!
     
    CRM likes this.
  9. Matt69olds

    Matt69olds Full Access Member

    Posts:
    1,329
    Likes Received:
    1,585
    Joined:
    Jan 8, 2018
    Location:
    Central Indiana
    First Name:
    Matt
    Truck Year:
    81
    Truck Model:
    GMC 1/2 ton
    Engine Size:
    455 Olds
    Evacuate the system, see if it holds vacuum. Run the pump for at least a half hour, it should hold a vacuum overnight. If it slowly looses vacuum, soap and water won’t show anything. Recharge the system, get a can of 134 with the fluorescent dye. Run the system for a while, then use a black light to illuminate the dye. The fluorescent dye with highlight the leak, Stevie wonder will be able to find it.
     
    Poppy 87 likes this.
  10. Old60Driver

    Old60Driver 1983 K20 Silverado

    Posts:
    119
    Likes Received:
    126
    Joined:
    May 17, 2020
    Location:
    Houston
    First Name:
    Michael
    Truck Year:
    1983
    Truck Model:
    K20 Silverado
    Engine Size:
    350
    Man, this is why I love this place; you guys rock!

    Hoping to get some time to wrench on her today. Unfortunately, I've been away from home for the better part of 2 months, and the my 'honey-do' list is ever increasing! Hell, I haven't even made it to the gun range yet! o_O

    Thanks for all the help y'all, it's damned appreciated!
     
  11. Old60Driver

    Old60Driver 1983 K20 Silverado

    Posts:
    119
    Likes Received:
    126
    Joined:
    May 17, 2020
    Location:
    Houston
    First Name:
    Michael
    Truck Year:
    1983
    Truck Model:
    K20 Silverado
    Engine Size:
    350
    Okay y'all. Got a little time to tinker...

    None of my local parts houses had any gauges or vacuum pumps to rent. Rather, they rent them, they're just all out currently. It's pretty dang hot these days, so that makes sense. I found a Harbor Freight that had both, and picked up gauges and pump. About $110 for both, after coupons.

    So, I hooked everything up, engine off, and checked for pressure. Nada. Empty. So, I set up for a vacuum, to see if I could find the leak, soapy water (heavy soap) in hand. Pulled the vacuum, and after a minute or two, she stabilized on both gauges. Low side reads about 30 inches of vacuum, and the high side reads some vacuum. Let that sit for about 10 minutes, shut the pump off and went hunting for the leak. I didn't see anything obvious. So, I let it run for 45 minutes, shut the pump down, and let it sit for another 10 minutes. It looks exactly as it did before. No loss of vacuum.

    How could my system lose all that freon in 2 hours, and not lose ANY vacuum in 45 minutes? Should I try the same thing with the engine running?

    Could a shaft seal in the compressor be leaking ONLY when in a certain position? Could the schrader valves be leaking? Truth be told, I've NEVER tinkered with AC systems. I've been tinkering with engines for as long as I can remember, but never messed with the AC systems, so any help is appreciated!!!

    Thanks folks, and Happy Fathers Day to ya!
     
  12. bucket

    bucket Super Moderator Staff Member

    Age:
    39
    Posts:
    24,047
    Likes Received:
    11,191
    Joined:
    Aug 3, 2010
    Location:
    Usually not in Ohio
    First Name:
    Andy
    Truck Year:
    '77, '78, '79, '84, '88
    Truck Model:
    K5 thru K30
    Engine Size:
    350-454
    Yes, sometimes pulling vacuum will not show a leak. A little bit of vacuum may not stress a seal like 60+ psi will. It also could be a leaking Schrader.

    And just a friendly reminder in case there is the chance it could happen... never ever ever charge the system with freon that includes a stop-leak.
     
  13. Doppleganger

    Doppleganger Supporting Member Supporting Member

    Posts:
    3,247
    Likes Received:
    9,641
    Joined:
    May 24, 2019
    Location:
    OH-MI: Just like it sounds
    First Name:
    Chris
    Truck Year:
    1985
    Truck Model:
    K20
    Engine Size:
    5.7
    My Outback had a slow leak last Fall. Place checked it for vac - fine. Recharged it and put a fluorescent leak detector in it. It still blows cold to this day but the entire left side of my condenser now glows in the dark. Only thing we can figure is there is times of higher pressure that forces open a small crack - dunno.

    I picked up a new condenser and lines (cheap at Rock) anyways.
     
    Shorty81 and bucket like this.
  14. Old60Driver

    Old60Driver 1983 K20 Silverado

    Posts:
    119
    Likes Received:
    126
    Joined:
    May 17, 2020
    Location:
    Houston
    First Name:
    Michael
    Truck Year:
    1983
    Truck Model:
    K20 Silverado
    Engine Size:
    350
    Roger that, I've run into tons of problems with that stop-leak stuff. Obviously not on A/C systems, but power steering, brakes, transmission, etc... lol

    That being said. I think I found the problem(s).

    Like I said, I couldn't initially find the leak through vacuum. It was dropping, but VERY slowly. I had lost a few inches in 41 minutes, but still couldn't find it.

    So, I did something. Hopefully, it's not stupid, and I haven't gnarled my system up.

    What I did, was PRESSURIZE it. I made a quick adapter for my gauges, and threw in about 60 pounds of pressure. Then the problem was obvious.

    It was my accumulator. Rather, both of the accumulator connections. Remember when I said I replaced it? Well, evidently, I wasn't wearing my big boy undies when I tightened everything back up.

    Pulled the seals, oiled up a new set, and pressurized her again. She's holding rock solid. Plus, I was able to check everything else with pressure. For me, it was easier to see.

    Anyway, I'm gonna let her sit for a while, then pull vacuum for a good bit before trying to charge her.

    So what say you? Did I do something wrong here? o_O

    Thanks again!
     
    CRM likes this.
  15. bucket

    bucket Super Moderator Staff Member

    Age:
    39
    Posts:
    24,047
    Likes Received:
    11,191
    Joined:
    Aug 3, 2010
    Location:
    Usually not in Ohio
    First Name:
    Andy
    Truck Year:
    '77, '78, '79, '84, '88
    Truck Model:
    K5 thru K30
    Engine Size:
    350-454
    I prefer to pressurize with freon and some dye, but I can see where that would upset some folks.

    Did you match up your accumulator o-rings with the originals or use the ones that came with the new one? Many times, a new accumulator will come with seals that are too thin.
     
    CRM and Doppleganger like this.

Share This Page