HVAC

thank you guys for the advice you gave about cleaning shell tube for the plantroom ,its now working fine after the service.I commissioned 4x 54000btu ACs yesterday .The running pressure was 40 to 45 psi.ambient temperature was 22degrees set temperature was 18degrees and room temperature before AC was 20degrees .Is my refrigerant ,r22, ok,or i need to add more .My machines are working perfectly.Is my refrigerent level okey since during hot season we usually charge these machines upto 60psi.Will i not have the problem of low cooling during hot season,or ,is the low pressure being caused by generally low temperatures , .