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

All the instructions are with the car running. Even the one in your link is with the car running, can upside down. Where are you reading the car is off?

I'm just telling you what is written on most cans of Freon: shake and turn upside down periodically. Those cans are under very high pressure. You won't have pure liquid escaping unless the pressures are zero in the can. They also might have a straw inside, like a spill proof baby bottle, so when you turn upside down you have no spillage. The agitation and direction change would help to ensure all contents are expelled uniformly.

you can turn the can upside down to initially charge it into the hi side.
charging into the low side the can is always right side up.

now, people do charge liquid into the low side. i have done it. i dotn make it practice to do it but i have. has a compressor been killed while doing it, probably not. has it been damaged but still works, probably not BUT, you never know.

Charging into the high side??? What??! Never heard anyone charging their systems from the high side. The cans always connect to the low side, and the instructions on most cans are to agitate and rotate periodically, turning upside down at the end, with the AC running. Period.

http://idqusa.com/instruction/arctic-freeze_2013

The OP asked how long it takes to run in a can of R134. I told him maybe 5 minutes or so. Anybody else been responsive to his question?
Thanks,
Dave

Hi Dave,
Yes one other offered an answer my question - 2-3 minutes.
I have noticed that A/C threads often goes off track pretty quickly. I do appreciate you feedback! Wayne

That's good Wayne. After 23 posts, I forgot.
Good luck,
Dave

From research..

"On the clock" A/C technicians often fine ways of doing things more quickly, things no DIY should do. Without the engine running, and with vacuum still in place, the technician opens both manifold valves and FLOODS the system with liquid refrigerant, no more than 80% by weight.

Now the engine can be started and the system topped-off the same way as a DIY.

There is also a note indicating sometimes use of the low side manifold valve being used, carefully, as an orifice, liquid in, gas out.

With regard to charging systems with the can upright or inverted either way can be used. If I have a vacuum on the system I will purge the line going to the manifold gauges and charge the high pressure side with the can inverted charging only the high side with liquid and the compressor OFF.

Never under any circumstances charge the low pressure side with liquid with the compressor off even under a vacuum. The pistons in the compressor don't like liquid if any kind and will cause damage to the pistons - it's called hydraulic shock.

Now once the system will not take any more refrigerant with the compressor off, close the high pressure side manifold gauge, start the engine and turn on the compressor.

You can now finish charging the system with either the can upright or inverted on the low side. Now if you decide to charge the system with the can inverted you need to only crack open the manifold gauge valve on the low side ever so slightly and start charging.

My gauges have a sight glass so I can monitor how much liquid is being charged into the system. I usually allow the sight glass to fill half way with liquid. By doing that the vacuum on the system is deep enough to cause the liquid to expand into a gas as it enters the compressor.

The system can be charged faster by using this method and there is no chance of damaging the compressor as long as the low side charging valve is cracked open enough to allow a low volume of liquid to enter the system. The can will start to get cold as the system is charging sio you know the refeigerant is entering the system.

One note of concern if you notice frost on the connection at the compressor you are allowing too much refrigerant to enter the system. Hope this will clear up the question regarding "inverted vs upright" charging methods.

Somehow things always drift from the OP's question in A/C threads.. The logical answer is when the lowest pressure is established on the low side, the can of refrigerant is at its largest amount of intake.. Rev the engine to about 2k, and watch for you lowest low side pressure reading.. At that point your system has received all the refrigerant it will receive from the can.. Close the low side gauge.. Monitor your gauges.. If your temp/pressure is acceptable (many variables here), you are done.. I do not recommend charging from cans, but it is what is.. I weigh in charges with a 30# cylinder and adapt from there.. DYSers use cans and you can get close.. Good luck and stay cool!!!

there really is NO answer that would do him any good. its not a time thing. there are many variables that can cahnge the time. is it the first can or that last. does he heat up the cans, does he raise the RPM's. what are the low side pressures.
what is the outside temp. are there any porblesm with his system. is his engine running.
it could take 5 minutes, it could take 20 minutes.

using a set of AC gauges, you connect them to BOTH the hi side AND the low side. when charging a system it is best to see what is going on with both hi and low side pressures along with vent temp. it best to take in as much info as you can when charging the system.

when the system is empty you can charge on the hi side with liquid and the system off. you want to do an initial charge before you turn it on. liquid just tends to go in faster.
the reason you "swirl" the can is so the refridgerant picks up heat from the outside of the can to raise the pressure. (thus the hot water).