I have a window unit ac/heat unit. There is a black jelly like substance on the coils behind the filter. How do I clean this off? Thanks for your help

Use a good household cleaner like 409 or fantastic. Take the unit outside with the cover off and spray it down without getting any liquid on the motor. Flush with clear water and you are good to go. There is a special cleaner made for A/C use byt for such a small job I would not bother with it. You probably have mold growing in the unit.

Also I use an old paint brush to gently brush away