We have a one year old 21 ft with the 2663 Dometic fridge. Recently we have noticed a decline in performance. It used to keep the fridge section in the mid 30s without much trouble at a setting of 4. In the last couple of months it has reached a point where it we need a setting of 5 to keep it in the low 40s. This is true for both gas and AC. What do I look for that might need some maintenance?
I have the Texas fan option and had never used it until recently to see if it would help. I never had it on while driving so I assume the thermal fuse is still intact but I have no idea if it actually runs. Didn't see any difference in the temps. Where is the fan mounted? Up top in the exhaust stack?
Most likely you need to clean the burner/orifice and look for spider web material that constrains the airflow in that area or the boiler shield. Search "dometic fridge cleaning" on You Tube for several videos on how to do that.
A gradual decline in performance is normal over time without maintenance; absorption systems either work or die as there are no moving parts to wear out.