2003 Toyota 4Runner blinking a/c light - hot air

Blinking A/C light on my 2003 Toyota 4Runner.
Must have a slight leak, I would add refrigerant from a can and be good all summer.
This year although I replaced the A/C relay the a/c light on the dial flashes and I get hot air.
My compressor starts to engage and instantly cuts off.
While engaged for that second or two a tin can rattle type sound occurs and the pressure drops to zero.
With the engine off the low side pressure reads high and is slightly beyond the beginning of red zone (alert).
Any general experiences or possibly with those V6 4Runners would be much appreciated.