ac low side manifold gauge bounces

[Capt dong]

from 30 to 90 psi. static is about 100 psi in 90 degree heat.

compressor runs about 10 seconds which raises pressure to about 90 then shuts off and goes down to about 30 and starts all over again. whats this mean? i being told low refrigerant or a ton of other problems.

[Capt dong]

just added a can of r134a. stabilized the gauges at 35 and 220. theres a leak on my low side valve. gonna try to find a tool that replaces without discharging locally. i think i sae one on oreillys website. hope they have in stores.

rented the gauges frim autozone with 100 deposit.

thermometer from vents showing 50* instead of 70-80* depending on outside temp. right now upper 90s.