Honda accord ex wagon 92' reads hot

[Honda682]

I have a 92 honda accord its reading hot inside the cabin on the temp gauge but when we pop the hood and use the temp gauge it isn't going over 186 degrees. We replaced the sensor and are constantly checking the fluids which are fine. I'm not sure if it is the temp gauge because sometimes it will read perfectly normal for an extended time then just skyrocket. Mechanics seem to think it is the gauge and are going to either replace it or put a dummy light in to let me know if it overheats (cluster has already had to be replaced once) I've only had this car for a little over two months and it started right after an oil change (only the oil was replaced not the filter because they were unable to get the filter off but it still had 3k on the filter). Any idea's? I'm just looking for others experiences or any alternatives due to I do not have another cluster I can put in and haven't had any luck finding one in a reasonable price range.