DOMETIC 12K reverse cycle issue

[tonyiiiafl]

Last August I bought a Dometric 12K BTU Reverse cycle unit and the SMXII controller. It was EBAY number 264357583158. I bought it from Citi Marine and the seller was fantastic to work with. The unit worked great and has all summer, except for a few occasions. Today again, the set point was at 70, but the temp got up to 76, and it has done this a few times. I can adjust the temp, but the only thing that works is to shut it off and turn it back on and all works great. I have seawater flow, clear strainer, water coming out from cooling the unit, and filter is clean and unit is NOT icing up. Can you give me some guidance