Heater core leaking

Sweet smell in cabin. Wet carpet on passenger side. Fogged windows that won't clear. Sometimes visible coolant dripping from under dash.

Heater cores are made of thin copper tubing. They corrode from the inside out, especially if the system hasn't been flushed in decades.

1. 1 Bypass it temporarily: loop a hose from heater inlet to outlet under the hood. You lose cabin heat but can still drive
2. 2 Replace it. Dash-out job on a 122S. Budget 6-10 hours if you've never done it. New cores ~$80-150 from specialists
3. 3 Flush the system before installing a new core or it'll clog immediately