Now is the time to find the leak. There are probably different methods. If the system has enough gas in it then they can use the soap test, leak will probably be on the high side. If the leak is on the low side then you can actually suck air into the system when it gets low and then the coil can freeze up or the expansion valve can be blocked with ice. So fix the leak, then put the whole system under vacuum (no loss of vacuum confirms leak is fixed) to make sure there is no water vapor in the lines. Will probably have to change out the filter as well. Get it done right the first time!
