Diagnosis
In most cases, this isn't a heating problem. The main culprit is rinse aid—either the dispenser is empty, or it's not dispensing properly. Without rinse aid, water sheets up and sticks to dishes instead of sliding off.
How to Fix It
1) Fill the rinse aid dispenser (it's on the inside of the door, usually a twist-cap). Use only rinse aid designed for dishwashers. 2) The dispenser has an adjustable dial, often numbered 1-6. For poor drying, turn it to a higher number (like 5 or 6) to release more rinse aid per cycle. 3) Run a hot wash cycle to clear any old, gummy rinse aid from the dispenser mechanism.
If That Didn't Work
Check that the heating element is actually getting hot at the end of the cycle. After a wash, once the noise stops but before you open the door, feel the outside of the door. It should be very warm. If it's cold, the heater or its control might have failed.
Heads Up
Using too much regular dish soap or pods with excessive sudsing agents will also cause poor drying and film. Make sure you're using detergent specifically for dishwashers.