A squeaking Fan-Tastic roof fan is typically caused by worn motor bearings, dirty components, or loose hardware. Most cases can be fixed with cleaning, lubrication, or bearing replacement.
New sensor resistance not matching suggests compatibility issue or wiring problem. Verify 8330-3101 is correct for your specific thermostat model with Coleman/Airxcel. Check resistance at sensor ends vs thermostat end of wiring.
When your Airxcel furnace doesn't respond to the thermostat, start by checking the 12V power supply, thermostat wiring connections, and propane supply. Most issues are electrical rather than propane-related.