Just curious as to what might cause the fridge to work on 110 and 12v but not propane? Everyone says the propane seems to work better than the other means. I lit the propane for 2-3 hours and zero cooling occurred. The pilot is lit I can see through the window. With the 110v it cools pretty quickly and the 12v seems to keep it going when already cool. Any tips for workup/diagnostics?

Its old. 1990 camper and original fridge.