I've heard that a person can insulate the the exposed surfaces of the drip pan to help stop the condensation. What are your thoughts on this? If it is possible how would I do the job?

My Nordyne C3QA-042U-B A coil in leaking condensation on the inside of the coil and drip pan its running down the inside onto the furnace. I've cleaned everything and its still happening. I'm not sure if I have a drain trap how would I tell? Also, I've read that a coil box might help, is installing ...