Just found the indoor coil for the AC is really rusted when the furnice was replaced today. I was told that it had some water leaking down to the furnice, so that it should be replaced.
The AC is about 15 year old, but was told it is still working (when we bought the house a couple months ago).
I am wondering which option is better: 1). to spend $3K to replace the whole AC (which is a bit too much for me now), or (2) just replace the indoor coil, and the let the AC work for me for a few more years.

Considering the end of March is coming really soon (which affects the rebate), I need to make the decision asap. Any advice/suggestions are welcome.

Thanks