Norcold N300.3 inconsistent propane functionality...

Your Nordcold N300.3 is a 3-way rv fridge
120VAC electric element
12VDC electric element
Propane gas burner

There is NO pilot flame...the flame that you ignite with the piezo sparker IS the main flame
*thermostat is NOT an Automatic gas control system---flame is ON all the time
YOU have to Manually adjust amount of cooling by adjusting the thermostat setting

Thermocouple is used to PROVE Flame is lit so Safety Valve stays open
Loss of Flame Signal (few milliamps generated by heated thermocouple) and safety valve closes

*Dirty thermocouple
*Bad connection on thermocouple and/or interrupter
*Bad thermocouple

Least likely....dirty orifice/burner

Service Manual N300 series
Pg 5---Controls
Pg 6...Operation
Pg 10..Troubleshooting Block Chart for Gas Failure