Q: heating and cooling on 1990 Saab 900

The temperature gauge for outside climate goes up and down causing the air condition to go from cool to heat and vice versa..... Plus my head lights go out...... these are two separate problems

I have a 2008 Chrysler Aspen 5.7. The air conditioning blows up full power and one day just stopped blowing cool air. We had a guy come out and put freon in and we heard the hissing sound that it was leaking out. How do I know that it's just a patch job or something more serious? We live in Miami and my husband drives for a living and is borderline heat stroke. How do I know if it's something easy or very expensive?

My engine and radiator overheats after a mile or two of driving once the radiator overheats there's a small leak underneath the hose from the radiator that distributes the fluid from the radiator to the engine block could this be caused by corrosion could this be fixed by Flushing the radiator it was leaking from a black piece underneath the hose on the side of the radiator same place it is leaking from now over a month ago I put some block seal in it and it stopped but when it heats up is the only time at leaks from there could this be corrosion build up can it Be fixed by just Flushing