When the unit is turned on in the inside the outside unit is not responding. I believe it is low on freon which is preventing the low pressure switch from coming on. When this switch is pressed manually the unit comes on.

hvacservicetech_07

I believe the switch you are refering to is a high pressure switch, most low pressure or loss of charge switches are not manual reset. If that is the case, be sure the outdoor fan is running, if it is, try cleaning the outdoor coil. What is the Model of the condensing unit?

T-Top

The red button around the refrigerant lines is a high pressure switch. If you have a Rheem heat pump, not uncommon for this to happen with the switch from heating to cooling season. If its tripping in cooling mode make sure your condenser coil is clean on the out door unit if not spray it out with a water hose and see what it will do(make sure the out side fan is running when calling for cooling). In cooling mode it trips from lack of air movement across the out door coil or refrigerant line restriction.