96 850 - Added R134A, Now Confused

BigRed · Post by **BigRed** » 01 Sep 2013, 13:17

I picked up a can of R134A and a Charge Hose with Gauge. When I disconnected the hose from the low side port I heard a hissing. That's when I realized I didn't turn the handle back to seal the can. So I just moved it off to side, figured nothing I could do now as whatever little bit was left in it just escaped. I never disconnected the charge hose from the can and when I went back the next day to cleanup I found the gauge in the red danger range while connected only to what I believe to be an empty can. Even if the can were not empty, isn't it only 45 PSI? Any ideas whats going on? Think it would be safe to disconnect the can?

Thanks

Post by **Ozark Lee** » 01 Sep 2013, 16:04

As you charge the system the pressure drop in the can causes the can to drop in temperature. As the temperature decreases the flow of the refrigerant slows, in some cases nearly to a stop. Once the can heats up again the pressure increases, even if there is a very small volume of refrigerant left in the can.

The can is not only at 45 PSI when it is fully loaded, its pressure can be much higher depending on the ambient temperature.

Just slowly unscrew the can and throw it away, there won't be much that comes out of it.

...Lee

BigRed · Post by **BigRed** » 03 Sep 2013, 07:23

Thank you for the clear information.

My incorrect assumption regarding 45PSI came from reading that it was not possible to over-charge the system using cans.

I still don't understand how there could be anything left in the can as the hose was disconnected from the vehicle port, and the valve was wide open. Is it that the coupler at end of hose has a schrader valve, and only flows wen connected to the low-side port?

Post by **rmmagow** » 03 Sep 2013, 10:02

I don't know if this is applicable but I know some people/sites will talk about putting the can into warm water to help refrigerant flow. OK, I was young, stupid and filling an R12 system and did put the can into some warm (too warm) water to help flow, went in the house to grab a beer (2nd mistake, I was young), the can exploded, blew a chunk of metal through my hood breaking the windshield, pan of hot water was completely disintegrated . Had I been standing around watching this I would have had my head removed.
Be careful with A/C there can be a lot of variables coming into play. I don't know if R134A can exhibit this behavior.

Post by **abscate** » 06 Sep 2013, 04:53

You can definitely overcharge the system with cans. These cars only take 2 cans in total whole charge so one can is a lot of juice.

I have seen can/ hose setups both with and without Schraeder valves so I think your reading of 45 psi on the empty makes sense.

You really have to fix the leaks in the system if you are putting more than a can in every two years - both for the saKe of the environment and your pocketbook.