The switch in the outside compartment is the Suburban OEM ON/OFF swithc for electric element
120V AC from a circuit breaker goes to that switch (in series with any RV MFG. added switch) via Black hot wire then to the high temp t-stat (top one...resettable) then to normal temp t-stat via wire connector and then to element. Thru element and back to main panel via common white wire
The OEM on/off switch is just a snap in toggle switch and common problem due to location/exposure.
Gas side works cause it is ALL DC and separate system
Electric is ALL AC.....bad switch.