Re: how much A/C charge to put in?

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Posted by OnBelay ( on 08:06:45 06/13/14

In Reply to: how much A/C charge to put in? posted by Peter

Ol' Uncle OnBelay is going to step in with his "fix it right or don't bother because you're only screwing it up worse" attitude.

When an sealed system like your truck AC has a leak, there is more going on than just the refrigerant leaking out. The oil which is mixed with the refrigerant will leak out at a higher proportion than the refrigerant does, thereby putting the system components that require lubrication (the compressor) at risk.

Additionally, when the system is compromised, it also allows air back in, and compresses/pushes air instead of refrigerant.

The next potential problem in your scenario is that most "consumer use" add-a-can refrigerants have a stop leak of some kind, and for a long term repair this is one of the worst things you can do to yourself. The same chemicals that find a leak and keep the gasses now in the system trapped also go pool in tiny orifices in the evaporator, compressor, and accumulator and harden, making the system at least work harder and at worst stop refrigerant flow altogether.

While you may have emptied two, one pound cans into your system, it was not 100% virgin refrigerant. You have added a mixture of refrigerant of unknown quality, stop leak, air, and maybe a little (but not the correct proportion of) oil. I have no doubt that you have way more than three pounds of something in your system, but it ain't refrigerant.

Your system is intended to have three pounds of pure refrigerant with approximately two ounces of oil, nothing else. That is why, when a proper repair is performed, the system is drawn to to a vacuum, and the system is tested to hold pressure. Then pure refrigerant and oil are added. The system pressures are them measured, and system efficiency and efficacy are determined by the measurement of pressure with the proper system content. In other words, the pressure readings you are seeing right now are not accurate because you aren't measuring the right stuff.

The risk you run by continuing to nurse the system along this way is that it will run, and run, and run...without proper lubrication. Proper diagnosis, replacing a leaking hose, vacuuming the system, recharging and testing may be a $250 repair. If the compressor runs too long without appropriate lubrication and starts to let go, it will put wear metals into the system and you will need to replace hoses, compressor, evaporator, accumulator, etc. and will have a $2500 repair bill.

Yup. Fix it right, or screw stuff up.

After all, the truck's reliability rating isn't going to improve without an investment.

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