Overcharged My A/C?

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I overcharged an escort once. the pressure got so high it blew a fitting apart at the silver can looking thing. nice loud noise. nice dent in the hood.
 
Originally Posted By: tomcat27
I overcharged an escort once. the pressure got so high it blew a fitting apart at the silver can looking thing. nice loud noise. nice dent in the hood.


How much did you overcharge it by?
 
If you already ran the unit and you did not slug the compressor with liquid and blow out a valve then it probably will never be a problem.

The main problem with over-charging is that if liquid gets sucked into the compressor the piston (or rotary vane, or wankel piston, depending on the compressor design) can not compress a liquid and will blow out a valve or damage something in the mechanical drive of the piston. This usually happens before you get the hood closed.

So if you ran it and it is still working then it is probably never going to be a problem.

Also you should know that most AC systems including most cars have a duel purpose section that is basically a large can or piece of pipe called an accumulator to hold extra charge and prevent liquid from being sucked into the vacuum side of the compressor. In most car system the accumulator is a duel purpose section also containing a desiccant that absorbs any small amount of moisture left in the the system after vacuum pumping it down so that moisture does not get to the orifice and freeze it up. Sometimes in car systems the material holding the desiccant breaks and the desiccant gets loose into the system and ends up clogging up the flow in the pipes, and or the orifice screen.

The fact that your car has an accumulator should let you forget about any problem of over-charging by a few ounces.
 
Originally Posted By: JimPghPA


The fact that your car has an accumulator should let you forget about any problem of over-charging by a few ounces.
Actully his car has a very small reciever dryer and not an Accumulator.

Since the system is very small (1.5lbs) just a few ounces over charged will have an effect on it. I'm guessing 3oz would make the high side pressures go out the window.

But since he does not have a high pressure guage we do not know whats going on in there.
 
+1 on what Chris said. That AC system is small enough that even a few ounces of over-charge can put the high-side pressure WAY too high. And being that it's a pretty cheap vehicle, there's likely no high-pressure protection switch to shut the compressor off in such a scenario (some automotive systems have this, lots of trucks and heavy equipment have it... but a small, modern, commuter vehicle like a Saturn probably doesn't). If you run the AC this way in hot weather, you're risking not only a blown hose or something... it could easily tear up the compressor.

If that was my vehicle, I'd evacuate the whole system and charge it with the proper amount. Anything else is just a guess- even if you have the proper gauges (though that would be a much safer guess).
 
R134a systems don't like overcharges. A bit low is better than a bit high.
Get gauges, or at least a low side gauge. You have no idea where you are at. Take static cold overnight tests, and running tests. Note the cycling pressures on the low side.
 
Originally Posted By: Cutehumor
critic, are you on the original a/c compressor?

Yup.

One engineer once explained to me that the recommended charge is the ideal amount, and that there is a window of acceptable charges where the unit will still operate correctly. Is there any truth to this?

Of course, the best solution is to evac and recharge the entire system, which I think I'll end up doing anyway in the next few months to fix the leak. However, I remember that before I evaced and recharged the system in June 2009, the system was displaying similar behavior--- good performance when ambient temperatures are under 75F, mediocre performance in temperatures about 85F. And at that time, the system was about 1/2 lb low.
 
If you are having cooling performance problems, check the condenser too- if there are a lot of clogged or bent fins, clean and straighten them. It makes a big difference.

You can feel the temperature of the liquid side of the system, after the condenser. It will be warm, but shouldn't be hot. If it is hot, the condenser isn't removing enough heat.

A perfectly charged system will generally be one that has the greatest difference between the high and low sides. All other things being equal. Too little refrigerant and it doesn't have enough high side pressure, too much and it can't pull the low side down far enough.
 
The strange thing is, I just went out to my car and powered on the A/C and it has never worked this well before. The outside temperature is in the mid 70s.
 
Quote:
One engineer once explained to me that the recommended charge is the ideal amount, and that there is a window of acceptable charges where the unit will still operate correctly. Is there any truth to this?


Yes, this is true. And it can be a fairly wide range. A lot of OEM manuals will give a pretty wide range of acceptable high & low pressures according to ambient temperature. I think there's a fair chance that your charge will be within the acceptable range from what you've told us.

That said, it's only a guess- and you're still taking a chance. It's a chance I'd be willing to take if I hooked up a gauge set to it- both high and low, WHILE it's hot outside. But without making that check... I dunno.

I've seen a lot of compressor failures cause by overcharging: shade-tree mechanics just guessing where they're at. Even systems with a high pressure cutoff switch can be damaged this way- particularly if the condensor is dirty. High pressure=high heat=not a nice thing to do to your compressor.
 
Originally Posted By: mechtech2
R134a systems don't like overcharges. A bit low is better than a bit high.
Get gauges, or at least a low side gauge. You have no idea where you are at. Take static cold overnight tests, and running tests. Note the cycling pressures on the low side.
Yes, the system will cool better when it is SLIGHTLY undercharged. John--Las Vegas.
 
Originally Posted By: onion
And being that it's a pretty cheap vehicle, there's likely no high-pressure protection switch to shut the compressor off in such a scenario (some automotive systems have this, lots of trucks and heavy equipment have it... but a small, modern, commuter vehicle like a Saturn probably doesn't).


The '96 Saturn SL2 does indeed have a high pressure cutoff switch. I just checked, because I have *NEVER* seen *ANY* automotive AC system that left the factory with R134a that also did not leave the factory with a high pressure cut-off, either implemented as a switch or, as is more common these days, with a pressure transducer that signals the PCM with the high-side pressure, which then cuts the compressor off if the AC pressure exceeds limits.

Most R12 systems do not have a high pressure cut-off, but you are supposed to add one when converting to R134a(to comply with EPA regulations), although hardly anyone does.
 
My 1988 F150 has a pressure relief valve on the compressor manifold. It relieves excess pressure in the system. I don't think that new cars and trucks have that valve though. Seems like they would but I don't think they do.
 
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