[bcw550ix]

Over the past couple weeks I've noticed a syrupy smell during the first few seconds of AC operation. I've also noticed that the coolant level has dropped below the MIN marker (even after I topped it up) and I see no evidence of an external leak.

Has anyone else experienced any leaks from the cooling system into the AC system?

[Stück]

Sounds like your heater core may be leaking into the evaporator case. Common problem with BMW's (and others) with a typical description of the symptoms. Are you getting a film buildup on the inside of the windshield? That is also a typical symptom even when its so little you can't smell it.

[bcw550ix]

Originally Posted by Stück

Sounds like your heater core may be leaking into the evaporator case. Common problem with BMW's (and others) with a typical description of the symptoms. Are you getting a film buildup on the inside of the windshield? That is also a typical symptom even when its so little you can't smell it.

Thanks for the reply. I haven't noticed a film build-up but will check. Any idea how involved replacement of the core is? It looks like this would be covered by the CPO warranty, so not a huge deal either way.