Suddenly lost charge

[rhedahl]

1990 Suburban with rear A/C

What would cause an A/C system to suddenly lose almost all of its charge and then hold its charge after being recharged?

The A/C on my Suburban suddenly quit working. I put the gauges on it and it had almost no charge. I recharged it and the charge seems to be holding just fine even after several days. I even used an electronic refrigerant gas detector and could not find anything. I'm pretty sure it has to be a very large leak for the system to suddenly go flat like that. What could be the cause of this?

[Cornbinder89]

About the only thing that will blow off the charge and re seal is the over-pressure safety valve found on some systems. There should be a tell-tail mess of oil if this is the case.
Otherwise, it is far more likely you have a slow leak. You gave no pressure or temp readings, so not much we can do for you.