> early models with auto-defrost and any models with door ice dispensers

I have one of these offenders. I cut the wires to the "always on" condensation heater and plugged the ice chute. I currently use a system to skip usually every other defrost cycle, but there is a permanent fix using a rheostat from those old halogen floor lamps to vary the power to the heating element itself (half is good starting point from what I hear).

Same. Replaced the automatic defrost heating element once. Which had the side effect of me learning of ways to vastly improve its efficiency, which may well be the biggest energy waster on these old fridges.

edit - almost forgot the "always on" heating element to prevent condensation in the ice dispenser chute, which also caused yellowing of the plastic (replaced and heater wires cut) until it looked like the house was inhabited by chainsmokers. These older fridges definitely weren't doing themselves any favors from an efficiency standpoint.