You can test the thermistor you have now before cutting in the new one.
Disconnect the thermistor harness from the P2, 2-pin terminal on the lower circuit board. Place the thermistor in a glass of ice water (more ice than water), approximately 33° F to 35° F. Wait 8 to 10 minutes. You should get a reading of approximately 8,000 to 10,000 ohms. Always test from the wire side as shown with the meter as not to create a connection problem at the P2 connector.
Check on page 12 of what I'm going to email you.
Mine goes to 32F with the stock thermistor. Since I added the chimmey vent fan it drops a lot faster and stays in that 32 to 34 range unless we have the door open a long time. Then it may hit 36 to 38 to later return back down to 32 to 34.
If the thermistor checks out, does it do the same 42 on gas or electric? or is one colder then the other? That is a trouble shooting lead if one is better then the other.
If both are not great then have you checked the flue to be blocked or dusty to death up top? If the draft up behind the fridge is blocked or obstructed that really affects the ability to cool.
Hope this helps
PS I thought you had a monster fan inside on the fins. H'mm maybe that is an issue taking a lot out of cool out of the fins in the center area and affecting the fins down by the thermistor. Have you tried it without the fan on? We use 2 Camco battery fans inside the fridge but they are lower in the compartment blowing air up.
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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