1. IF the 120 volt Heat Element fuse blows, one of the heat elements is bad Replace BOTH.
2. I find it hard to believe that a NORCOLD phone tech would tell a retail customer how to reset the board after a NO CO lock out.
3. A LOT of posts but NONE address the problem----NO CO
4. NO CO means that SOMETHING has caused the refer to NOT do a normal cool down. SIMPLE code---FIND the reason and when you fix the cause the refer will operate.
5. The MOST OBVIOUS cause of a NO CO on a 1200 is the rear cooling fans are not operating. IF they do NOT the refer throws the NO CO code
6. You have 2 chances to STOP a NO CO code. After the 1st code if you just restart the refer without fixing the problem(100% of people do this because they do NOT read the Norcold operators manual), the refer restarts and since you did NOT fix the cause then throws the 2nd NO CO and Locks Out the control board. THIS is the reason I find it hard to believe the OP talked to a NORCOLD rep AT Norcold. Norcold's policy is to NOT show or tell Rv'ers how to reset the lock out code because if you do NOT find and fix the problem it will throw the code again.
7. Fans not operating is the first thing. Disconnecting the Temp thermistor is the 2nd thing. Doug