I have a Miller Syncrowave 250 DX and it has 3 fans, 1 come on as soon as machine comes on and after welding for about 10min the other 2 come on but they are not

Do you mean to say that the other 2 should come on, but are not? Perhaps you are welding using lower settings than before, and the machine just isn't heating up as quickly. Is there a point at which the fans do come on? Say thirty minutes into the job instead of ten? Maybe you were afraid to run it too long without the cooling fans on and so stopped prematurely, before the thermostat turned them on? Check fuses and breakers.