Man can live without AC. Especially since we’re going into winter. If money is a concern, I doubt leaving it un-repaired until spring (or later) would cause further harm.

It is almost always cheaper to fix and keep a structurally sound car over buying a different one. Sure the Fit might be only worth $5k and need $3k of repairs, but I presume it is paid for. Another car which needs no repairs might cost $???k So you spend $3k and have a perfectly functioning car, or you spend $???k and have a perfectly functioning car. Whatever ??? is, it is greater than 3.

So, reasons to change cars.

1) car is structurally unsafe

2) hate the car and it is slowly killing your soul

3) fell in love with another car

That’s it, those are really the only reasons to switch cars. If you’re happy with the car and don’t daydream about another as long as the car is structurally safe, fix it.