Thermostat was sending a signal for heat even though temperature was above set point. Replaced thermostat. Preformed heating and cooling check. Unable to tested outlet gas pressure, tap screw has been stripped. Unit is kicking out on open limit, switched heat fan speed to black wire (high speed) to help with overheating. It did not help, system still tripping on high limit. Evaporator coil is dirty. Air conditioner uses old R22 refrigerant. Recommended replacement of heating and cooling system. Set up an estimate for tomorrow 3-5.