Portable AC creating too much negative pressure. HELP

[ShibaSpeak]

to properly cool that space you will need a 3 to 5 ton unit. your current unit is not able to keep the demand in an easy limit. that is why is it going hot to cold on you.
if you are hydroponic chill the water. 115 is hard to deal with indoors. you will need 3-4 times the normal ac to keep up and not have problems.

I only need to cool a well insulated ~10x12 room inside the garage not the entire garage itself. Worst case scenario from what Im told they have dual hose AC units that will cool the room with no air exchange and work fine but Id like to avoid that expense if I can.