Mildew found on AC coil

We bought a HUD property a year ago as new landlord, the heat pump is located in a second floor closet. When the AC panel is opened, lot of black mildew were found on AC coil.
What's the way to solve the problem. replace the whole unit? or have someone to clean it? is it a possible DIY project?

Appreciate any advice.

所有跟帖： 

• pictures would help -planotx- ♂ (125 bytes) () 05/07/2014 postreply 12:32:00

• 回复：Mildew found on AC coil -大叶猴魁- ♂ (72 bytes) () 05/07/2014 postreply 12:40:17