whirlpool akz151/wb temp fault

been on a whirlpool built in oven today, model akz151/wb service no:858515115010. customer complained about the temp (oven took 2hrs to cook pork chops). i checked the temperature and it was only 20 deg c under, but while the temperature was rising the relay on the main module was clicking on and off throughout, is this correct? or should the relay only operate once the oven reaches the correct temperature?, any help/advice is appreciated.