I thought it is made out of copper and aluminum, which is impossible to rust. I have a dispute with my warranty company now because they are saying the rust caused the coil to go bad and leak. Is this even possible? Any help would be appreciated.
I assume you are refering to a refrigerant leak in the coil. The coil has copper tubes with aluminum fins and galv. metal end plates and condensate pan. The galv plates will rust over time and deterioate the copper tubes causing them to leak. This is a Chemical reaction called galvanic reaction. Most manufacturer's are now using plastic to support the copper tubing instead of galv. for that reason. I hope this information helps. Let me know if I can help you anymore.
Stan Chaney HVAC/R