Adding R-134a - timing to empty a 12oz can???
 

My A/C charge is low and I want to add more R-134a.

Yes, my system was converted from R12 to R134a and yes I a have manifold gauge set.

My question is, if a whole 12oz can of R134a is needed in to achieve the desired pressures (based on temp/pressure charts for R-134a) - how long is a reasonable time for the whole 12oz can to be drawn into the system?

TIA,
Wayne

You'll never get a full 12 oz., but if you swirl the can and warm it a little , you'll get all you're going to get in 5 minutes or card.
Good luck
Dave

put the can in hot water. run the AC while you put it in.
low side with the can upright. gas only.

Thanks to all for your replies.

How exactly do you swirl the "car"? lol

Not that I'd do it... what would happen if one put in the liquid?

Multi-variables....

QUICKEST.....

Put the system under full load, max A/C, blower, cabin open to outside ambient, windows down and/or doors open.

The warmer the ambient the higher the can pressure will be and the wider the TXV will be open.

DO NOT heat the can beyond the point of lukewarm water. MORE, and the can may not be able to handle the pressure. Do NOT invert the can as that might result in liquid entering the compressor...DAMAGE!

Keeping the RPM elevated to ~2000 RPM will also help.

Good to know - Thanks!

Rotate the CAN back and forth no more than +/_ 45 degrees from vertical but not until it's so close to empty that the liquid will not "slosh" out.

wwest - I knew what he meant. Hence the lol - "Laughing Out Loud"

NO
close the windows and recirculate the air.
when you add the heat load of the outside air that RAISES the pressures, both low and hi, that counter acts the pressure in the can. you want the LOW side pressure LOW. what will let more refridgerant in, 25psi or 35 psi?
run hot water from your sink and put the can in that.

opening the windows will also give you a false reading of your pressures and you will under charge the system.

Sorry, Wayne, it was a typo. I meant swirl the can. Don't tip it much away from vertical or you may introduce liquid into your compressor, which is potentially damaging.
Dave

Dave, no need for apologies - I knew what you meant - I tried to make a joke - my joke fell flat - ma bad.

I kind of wish I could swirl the car. It might make the a/c cooler.
Good luck with your a/c.
Dave

63 degrees works better.

"close the windows and recirculate the air.."

If you actually NEED to add a full can of refrigerant then the low side pressures will not rise to high for the can pressure at ambient.

The OLD way was to have a high heat load so the compressor never begins cycling and fill until the sign glass indicates a satisfactory fill. Also, Porsche's documented method for checking the fill level.

That OLD method can still be used if one doesn't have guages.l

Make sure to use a box fan on top of the rear condenser (over the tail lid), and try to close the tail as much as possible to get max airflow through the condensor . When I did it, about 2-3 mins per can was all I needed, just shaking the can and turning upside down periodically.

Upside down is NOT advised, some compressors can be instantaneously damaged!

Rotating the can from vertical is also not advised if the level of rotation from vertical might result in liquid entering the system.

On heating the can.... Those cans cannot withstand the pressures one might inadvertently generate using HOT tap water, lukewarm at best and then only to extract the last of the can contents.

Haste makes waste and trips to the ER...

If you read the directions on most of the cans, it says shake and turn upside down every ~30 seconds? Have filled my system multiple times this way.

R-134a Check and Charge Hose

Message sent:

Your directions for the A/C charger say to turn the can upside down. If you mean to say with the engine off you should so state otherwise your directions are WRONG!

BTW I usually warm the can in the exhaust gases. It makes the r134 go in faster and empty the can better. You are looking right at the pressure gauges, so you should not get the pressure that high.
Dave