2003 MH and from description you have an ATWOOD (accessing element on backside)
That year model has completely separate controls for AC and Propane
(GC10A-3E I would suspect)
AC is direct circuit...no circuit board (circuit bd for GAS system and is very simple)
120V AC from Circuit Breaker to On/Off Switch *Inside installed by RV Mfg
From Inside On/Off Switch to OEM On/Off Switch *backside of WH Tank on cover over element (wires could be connected between the 2 switches with 'wire nuts')
From the OEM Switch to/thru set of T-stat (HI temp to Normal Temp---Hi temp has manual reset and set of t-stats under the cover on backside)
From T-stats to Element
Accessing backside is critical for any real testing and/or R/R of element/t-stats
Some RV MFG have a removable panel...directly behind WH Tank location, via a side compartment, from underneath RV
Some .have to remove water heater to R/R element/t-stats etc
***RV 'engineers/designers SHOULD have to do repairs/service for 1 yr apprenticeship prior to being allowed to design/engineer ANY RV
Supervisors that approve designs/engineering drawings should have to do 2 yrs ....or get fired for allowing some of the stupid design ideas to go into production