Amother a/c question

[JDUB]

Since a/c problems seem to be a hot topic these days, I have a question regarding the shrader valve on the low side charging port. I was going to put on the proper R-134a fittings on the service ports (the system was retrofitted and was charged with R-134a through some homemade hoses that used the original R-12 fittings). Anyway I was attempting to add the fittings and noticed some slight hissing from the shrader valve when I remover the cap. I don't want to put the fittings on if I have to replace the shrader valve. Should it be replaced or will the cap seal the the slight leak? Does the system need to be discharged to replace the shrader valve? or can I work quickly enough to replace it and not loose the full charge of refridgerant?

There is a special tool which can remove the schrader valve without losing the charge. However, the r134 valve adpapters that I have used in the past instruct you to remove the schrader valve before installing the adapter. To do this, of course, you will lose the charge. You won't be able to work quickly enough or safely enough to do this without losing the charge.

The good news is that you are losing 134, not the gaseous gold R12. If the system was correctly evacuated during the changeover, you should be able to blow down most of the charge, put on the fittings, then evacuate and charge. It's always best to pull a vacuum as long as possible, 24 hours if you can. This removes the maximum amount of water molecules. If left in the system, the water molecules combine with the refrigerant developing an acid that will potentially eat up components from the inside out.

Good luck,

[JDUB]

The retrofit kit from Interdynamics has two low side fittings one with external threads and one with internal threads. The one with external threads requires the shrader valve to be removed, the other one does not.
Thanks Larry for your input on this question, I will see if I can locate the shrader valve tool.