HELP!! R134a--how do you know when the can is !@#$% empty?
 

I vacuumed my system for three hours. It held at 29 for twenty minutes so I went ahead and started charging.

I have a digital scale and here are the weights before I began:

R134a 12 ounce can: 15.50 oz. (Can had net wt. 12 oz printed on it)

Weight of can with dispensing valve and yellow hose attached: 20.65 oz.




Ok, so I attached the can to the yellow hose, open the low side knob and I see some liquid through the sight glass on my gauge.

My enigine lid is down and I turn on my engine and hold at 2000 rpm.

I am looking at the scale dispay and it starts to drop. After few minutes it drops to 15.50 oz.

It stays there at 15.50 for the next five minutes.

I have no idea how long I have to wait, the sight glass shows nothing, and the can has frost on the outside.

I give it another few minutes then I think it must be empty. So I close the low side valve and disconnect the can tap.

A gusher of gas and frost shoots out for several seconds. I'm thinking: well i just contributed to global warming , wasted expensive R134a, and I have no idea what to do now.



Should I have waited longer?

Or maybe turned the can upside down? (I thought I was supposed to charge with gas--not liquid).

I did warm the cans in the sun as suggested to get it to flow better.

HELP!!:mad:

When the frost is gone from the outside of the can it is empty (or empty enough); also one can sometimes tell if there is liquid remaining in the can by gently shaking it.

"A gusher of gas and frost shoots out for several seconds."

Which is why one should wear safety goggles when servicing A/C systems. Jim

I agree that the advice is to charge with gas, but I've never been able to get a can any more than 2/3's or so empty without turning it upside down. Its probably my technique, or lack of same.

Thanks guys...I guess I have to more patient.

Turning the can upside down usually does the trick.

"Turning the can upside down usually does the trick".

Unless such action sends a slug of liquid into the compressor which overpressures it and blows the head seals or breaks valves and rings. Liquid is not very compressible. Turning the can upside down is poor practice. Jim

Place can in warm water.
Install only to recommended system capacity - no more, no less.

Sherwood