Evaporator Cleaning Access

[Rontx]

I recently had what I belive to be evaporator condensate leakage on the sheetrock below the area of the evaporator. It is a split system with a horizontal unit in the attic. While looking for information on cleaning the drain lines I realized that I have never cleaned the evaporator coil which has been in place since I bought the home in 1975. I would like to tackle this myself but am not sure the best way to access the coil. It appears to be fastened and sealed between what I believe is called a transition and a plenum. Rather than try to take this apart I would like to know if I can fabricate an access door in the transition that would allow access for cleaning? If this is feasible I would appreciate any tips you may be able to provide.
Thanks,
Rontx

[LazyPup]

Anyone who has read many of my posts could surely testify that normally I am a great proponent of DIY service and often I offer detailed instructions that go a bit beyond what many would consider a DIY project, but this is one area where I would strongly caution you to consult a pro.

Simply gaining access to the coil will require disassembling a portion of the cabinet however if you were to remove the wrong panel you could do serious damage to the unit, expose your person to non-insulated 220 wiring or damage delicate refrigerant lines or control wiring.

Cleaning the coil requires the use of chemical cleaners that are specially formulated for AC coils and the use of special "Fin Comb" tools made specific to this job. No only are normal household cleaners not sufficient to the task, many household type cleaners would leave a residue that makes the problem much worse. Any attempt to use a tool other than those designed for cleaning coils can and generally will result in damaging the coil and would result in a very expensive repair.