Good ol' A/C work. I've changed MANY condensers from wrecks at our shop. It does have a unique smell, like chemicals I guess. If the heater core has a leak, coolant would be leaking into the case. You would be able to differentiate the smells though.
If you want to be sure, take to a good A/C shop. They'll suck it down, make sure it holds vacuum, then refill to exact weight.
She's our "dont laugh its paid for" van. She got what she needed, nothing more. I'm afraid a pro would "total" her.
Now if we wanted to replace the compressor, then a pro would get it. We'd trade her in before that happened. We are at that point.