Carrier UNIT

This past winter, my heat pump would only run off of emergency heat. When summer came the AC worked good. It was a couple of weeks that we didn't use the ac or heat. However, Now the outside unit will not come on. My husband kick started by holding a contact button it, but the compresor ran for a minute than made a hiss noise, I am affraid of him trying to over ride the unit like that. Any Ideal what this may be? AC was working great so i have no clue. The fan in the squarl cage is coming on, but than it will click off. If you move the thermostat around it will come on than click off. the fan on top will not even come on