MKS SGEN L + hotbead temps and cooler on\off if bed temp > 90 (no replies)

Hello.
FW: Marlin 2.0.8 bugfix
board. MKS_SGEN_L
hotbead: mk2b ( PCB ) 12v

bead is heat to 110 celsius - normal
but when i start printing and cooler turns on hotbead cant holds 90+
so, i want something to add in firmware like:
if hotbead is mk2b and temp > 90 celsius cooler didnt turn on
cooler is setuped to J3(P2.4)

i use MOS, so 2 days try says what hotbead mk2b didnt holds temps like 90, normal for it i thinks 70-80

i`m not a programmer, but can do some things by myself.
so need advise or help to do such implementation