I have a vent less dryer with moisture is building up on the back side of the access cover .

There are two paths through the condenser for air to flow. One path is for the hot moist air from the dryer and the other is for the cooler room air. As the air passes through the condenser the cooler room air causes the warm moist air from the dryer to condense and it is directed to the rear of the cabinet where the pump can discharge the condensed vapor which has now become water. It is imperative that the air paths in both directions are clean on the condenser. The customer should not use fabric softener sheets in this style of dryer. The dryer should have a slight tilt to the rear to help the water flow to the rear correctly.

The hot moist air will condense where ever there is a temperature difference and by it occurring on the front of the condenser, it is apparent there is an air flow issue which is not allowing the air to pass through the condenser. There is a separate fan blade or blower wheel that moves the room air across the condenser, make sure it is not clogged with lint etc. I would also assume with these symptoms, that the dryer is taking longer than normal to dry a load of clothes. I would also make sure that the washer is spinning at full speed to eliminate as much water as possible, prior to loading into the dryer. But bottom line, I think you have an air flow problem.