After checking repair sites on the internet, I figured that either the defrost thermostat, the defrost heater or the defrost control board was at fault. I ordered and replaced the defrost thermostat which I found out didn't fix the problem. Then I checked the resistance of the defrost heater which checked out good. I ordered the Control Board as the last resort, replaced it and the problem was solved.
On all repairs I referred to helpful video sites. There was a little confusion on replacing the control board as the video shown was for repair of a similar model refrigerator. on my KitchenAid, there was a bezel over the front which had to be removed to gain access to remove and replace the control board. Ater a visual inspection of the replaced control board, I noticed that a relay component had a burnt spot on it.