My a/c seemed to getting weak (but still working), so got a gauge to check it. The low side pressure was 25. After adding a can of r134 it's still barely higher. Does this mean there's a leak? If there is a leak that's that bad (i.e. losing almost a whole can's worth of gas as soon as it's added), how was the a/c working at all? The hose connections all seemed to be tight. Could something else be causing the low pressure?