Without going into great detail about the circuit, its operation, and the function and operating range of the component in question, about the best we can suggest is:
- Secure it to make sure it isn't vibrating loosely. Varnish is good for this. It probably is varnished already, so don't get your hopes up.
- Dampen it to reduce the amount of vibration. Add some stiff rubber or foam goo (e.g., hot glue, "hot snot", some urethane glues?) and see if that helps.
- You may have no choice but to acoustically shield it instead. Add foam pads, rubber dampers to the PCB screw holes, close openings in the 'fridge enclosure, etc.
Mind that, if it gets warm in operation, you don't want to crowd it too much with gooey stuff. You may have to live with it...
Tim