My little boy is potty training and decided to urinate in the heating vent in his bedroom. I have washed it out with disinfectant and put baking soda in there to get rid of the smell, but it seems to be getting worse. Any ideas?

I hope he not continuing to use the heat vent. You might check on that. Urine smell is very difficult to get rid of. Sometimes the stuff gets down to the furnace and hangs around for awhile.You might try some fabreeze spray in the duct and the return air..

Can you open it up. If so spray it down with a bleach and water mixture and wipe it down. Duct tape a rag to a dowel or broom handle if you have to. Air freshener will only temporarily mask the odor.