tjkj2002 wrote:
R134A AC systems are filled by specific weight,not pressure.If you don't know how much is in the system you can't possibly now how much to put in.
This is essentially correct. Especially on automotive AC, since it is the easiest and most reliable way to ensure the correct charge on a critically charged system.
tjkj2002 wrote:
R134A is nothing like R12,freon is a dupont trademark name for there R12 by the way.
You have to watch this now. Chemours, who owns the trademark to Freon, is now slapping this term on multiple refrigerants, including R-134a, just to confuse then situation.
tjkj2002 wrote:
R134A will leak out at about 0.25 oz per year on a 100% sealed(IE no leaks) system since R134A molecules are much smaller then R12's and will bleed through the rubber hoses,no way to stop that.By the way all newer vehicles(last 20 or so years) have come with UV dye in the AC systems from the factory already since the high fail rate of R134A systems.
Correct. The hoses do have a known leak rate. Different depending on the the hose but your figure is a good average. It will take years to loose you charge that way normally.
Also compressor seals used to dry out and leak from lack of use over the winter. Since auto manufacturers were also trying to dehumidify when using defrost on the windows in the winter, they tied the AC operation to the defrost function, preventing most seal leaks now.
tjkj2002 wrote:
Plus most of those "DIY" kits at parts stores have stop leak in them and you do not want that stuff in your AC system,that is a $2000-$3000 repair bill since the entire AC system has to be replaced when you add that junk into it.
100 percent right That stuff is crap. Anyone who has had to change a plugged metering device on an automotive AC knows what a pain in the booty it is and the amount of hours it takes.
tjkj2002 wrote:
Without the proper tools and training you will do more harm then good.Just adding some R134A in is the worst idea ever and you need to know more then just the low pressure sides psi to actually figure out what's going on in the system,not to mention there are simple tests to determine if it's a electrical issue,mechanical issue,or a leak(low R134A).
Yes. Biggest problem with Auto AC systems is the environmental conditions can quickly change and the compressor capacity changes with RPM. You really have to understand how everything works together to determine how well it is operating.
This is why, as mentioned, weighing in the charge is the fastest and most reliable method. It also ensures if there is another problem, that the technician has now eliminated incorrect charge from the equation.
Sure, someone who understands basic electrical can fix minor problems, but AC is not for the average DIY.
I work on AC and refrigeration units, big and small everyday. You should see some of the stuff I have had to fix by people that were in over their head.
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