Hi , i have 2 inverters , first Pip4048MS (4kw) with firmware U1 72.60 and U2 04.10 this inverter workink fine but I buy annother inverter Pip5048MS (5kw) with firmware U1 72.10 and U2 04.12 , with this inverter i have one big problem , noise of fans . I think i have problems with firmware , i need help . Please