Is this a bad circuit board? (fridge)

45deg F is 5deg above the temperature that its is safe to keep potentially hazardous foods at. Yes that temperature and anything above 40deg F can cause foods to grow bacteria that is harmful to the body. Foods don't have to appear or smell spoiled to be harmful nor does "spoiled" foods always make you sick. Keep in mind that the longer the time at the wrong temperature will cause the bacteria to grow more and probably make you sick or worse.

Are you an Engineer??? I ask because you have given a lot of DATA, but have given NO IDEA what your problem is. Your main problem is the old chestnut----A Man with a Watch knows the time. A Man with 2 or more watches is never sure what the correct time is. I have never heard of a dangling Thermister causing a Refer circuit board to go to Protective mode whatever that is. The usual response to a dangling Thermister is to run all the time. Now, some refers(Norcold) DO go to a "protective" type response for a parameter out of spec. It is called BOS mode. This is just one of a few Norcold BOS parameters. Doug

Backup Operating System ("BOS")Your refrigerator features a Back-Up Operating System which provides a means for the refrigerator to cool in the event ofa failure within the refrigerator's operating controls. In the event this failure occurs, the refrigerator will display DiagnosticCode C5 and will switch automatically to the "BOS" mode. This mode provides refrigeration until the refrigerator is serviced.The fresh food and freezer compartment temperatures should be monitored to prevent over-freezing or thawing of refrigeratorcontents when operating in the "BOS" mode. If the refrigerator temperature is too cold, adjust the thermostat up (warmer) inone bar increments. If the refrigerator temperature is too warm, adjust the thermostat down (colder) in one bar increments.Allow the refrigerator to operate at the new setting for one hour before rechecking the freezer and fresh food compartmenttemperatures (frequent door opening prevents the temperatures from stabilizing). While the refrigerator can operate in thismode, Norcold recommends that you seek service as soon as practical to restore normal operation

Over thinking things.

Dump the 24/7/365 monitoring and don't obsess.

Your A/C and inside trailer temps has zero to do with the fridge temps.
RV fridges are exposed to the outdoor temps and seeing short 45F spikes on overly hot days is pretty much the normal range of a RV fridge. While 45F is sort of above my comfort zone for refrigerated foods it isn't going to kill you, it just means your foods will not last as long as possible.

You mention "overly hot" which I take as the daily outdoor temps and what you see for the fridge is a direct result of the outdoor temps.

Some RV manufacturers will include a couple of small fans on the back of the fridge to help with the high outdoor temps, perhaps you might wish to look into that but I doubt your going to see a big improvement.

Camping off level also does affect RV fridge efficiency, RV fridges use gravity to move the coolant inside the tubes, off level operation slows the coolant circulation (yes, I know, there are folks who claim the fridges were redesigned to work off level, but reality is off level operation should be avoided for best efficiency).

Consider yourself lucky, one of the RV fridges I dealt with would peak at 55F for several hrs with outdoor temps over 95F and then would freeze everything solid in the fridge when night time temps dropped to 70F.

Lot of 'data' that really doesn't get to the question

Brand/Model of Fridge??

Many fridge use a BOS (Backup Operating System) that ALLOWS for continuous operation (cooling) upon loss of temp sensing so food doesn't SPOIL

Thermistor is the temp sensor for the fridge thermostat. It measures FIN temp in food compartment...which is roughly 10*F lower then the food compartment
Thermostat is calibrated for temp range (approximately 34*F----44*F) based on each temp setting

Thermistor Bad.....usually results in overcooling condition

Circuit Board Bad....issues with heat source functions (short cycle)


Repeat/ask your question..........
*BRAND/MODEL for specific info on that fridge
*In AUTO Mode
*Any Error Codes
*fridge did get cold or didn't

What are you asking? Is the fridge getting warm when the outside warms up? Is the side of the trailer the refer is on in the sun? Do you have a fan to keep the air moving in the back of the fridge? We need more information as to what is your problem.