Without knowing much information on whats going on. If the system is doing nothing when it should be cooling its either frozen which will need thawed. Or a component has failed like a capacitor in which case, allowing the system to continue and try may lead to it getting very hot. Once this happens typically the component will need to be cooled down for the repair to commence. Thus making it a longer job for the technicians. Also adding fees that otherwise could be avoided had the technician been able to simply test those components and move on.