Norcold cooling problem

what temprature is the freezer getting to and how hot is it outside?

The reason may be as simple as the 120 is INOP. The freezer will NOT really lose cooling but the lower section will after you stated time frame. Doug

The BTU's for both 120 and LP are the SAME. 120 will cool just as good as LP. BUT, if the LINE VOLTAGE is below 114 volts, then the 120 element(also BTU) will be less to cool correctly. When you have marginal 120 line voltage then go to LP until the line voltage is above 115 volts. Doug

I was having similar issues with my Norcold NA10..freezer worked great on AC and gas, but no fridge cooling. I replaced the control board. It worked perfectly for three days, now it won't do anything on AC. I'm going to replace the control board again.

So Why does the freezer work perfectly on electric power?

There are more btu's from the propane than from the 120 volt heater.

The heater may not be "seated" correctly.

Check to see how many watts it is drawing--it ought to be around about 325 watt.

It is also possible that the 120 voltage is on the low side. Power varies by the square of the voltage so:

120 x 120 = 14400

and

110 x 110 = 12100

That's 16% less power, so only 273 watts.