Marine air passport control problem or not?

[Capt.Alex]

I am seeking advice from the marine air gurus here. Here's the problem: I have a self contained Marine Air A/C unit with the Passport II digital control. The unit cools fine, but the temperature reading on the display is off the charts. It's about 72 degrees in the boat, but the panel reads 127. As a result the system runs continuously because it can never satisfy due to the high thermostat reading. I have tried the following
1. Went through the programming mode and checked all settings including the temperature calibration ( it's so far out of whack that it will not allow me to enter enough of an offset to get even close to correct).
2. I tried a new Passport II control head, same issue.
3. I tried a new cable between the control head and the circuit board, same issue.
4. I installed an optional remote mount temperature probe in the return air grill to bypass the standard one built into the face of the panel, same issue.

My only guess is that there is a problem with the printed circuit board itself, am I missing something?