Looking in the Norcold 1200 Service Manual, I can't find an L1 Op fault listed. Are you sure you do not have a 1210? That has an L1 Op fault listed. You can get the 1210 Service Manual here:
http://bryantrv.com/docs2/docs/ncold1210.pdf
And the 1200 manual here:
http://bryantrv.com/docs2/docs/ncold1200.pdf
The model 1210 L1 op reset differs depending on the model Earlier ones do not have a resettable switch, while later ones do. You have to rplace the switch if you have an older 1210 - the new switch will be resettable. See the l1 op procedures in the 1210 manual.
Here is some more info on checking out the new Thermal Sensor installed in the recall fix. Apparently it can cause an Li op fault too.
http://mobilervmedic.com/HowtoDiagnoseNorcoldNewRecallKit.aspx