There could be several things going on but its a good chance there is a freon leak. First try turning the small red knob at the front of the frig, behind the kick plate/vent at very bottom, right-hand side, just in front of the water evap pan. This manual timer controls the defrost cycle and sometimes it get stuck.
Otherwise, you will have to roll the frig out and have a service tech try to fix it in the coach--four thru-floor bolts hold it in place. To replace/remove frig, you might could take the frig doors off and get the frig thru a mid-door coach opening but havent tried it. No way thru a front door coach--you have to take out the coach side window as the frig was installed at manufacture. Do a "search" on this topic using the search feature on the forum--lots of info on the Amana frig----good luck.
2003 40' MDTS
Garden Ridge, Texas