If your ductless mini-split system isn't working, you should check to see if the power is on. If the power is on, you should check the air filters to see if they need to be replaced. If the filters don't need to be replaced, you should check the circuit breaker to see if it has been tripped. If the circuit breaker isn't tripped, there may be an issue with the system. You should contact an air conditioning technician to come to take a look at your ductless system if you are unsure what the problem is.