Both gas and electric energy should provide the same cooling. They both use the same thermistor for control.
How old is the unit?
Has it ever worked correctly?
The first thing I'd do is check the resistance of the electic element to make sure it meets specs. Unplug the element and check the resistance across the leads. It should read ~44 ohms.
If it isn't that, then I'd pull the flue baffle and see if it's dirty. However, if it is, that should affect both gas and electric cooling.
Salem 29RKSS Pushing a 2500 Mega-Cab CTD!
Gotta go campin!