Micro/convection stops every minute

Question

i have a convec/micro model r1870 and ity stops every minute on the dot why?

I have an Amana ACO1180AB in my RV. It also stops every 59 seconds. The RV Manufacturer has gone out of business and I have no manual. Does anyone know where I can find a manual, it's not available on the Amana site. If someone has a suggestion on how to correct the problem with my Microwave/Convection oven Id love to hear from you. Thanks