My outside refrigerator had some water under it and a mold smell has stayed under the bottom of the fridge. We have continued to use it for the last 3 years outside on our patio.
Probably just pouring white vinegar down there, or moving the fridge and then mopping the area with full strength white vinegar would do it. You can also add some drops of tea tree oil to make it even more deadly to mold
You need to clean out the drip pan. Remove the grill from the bottom to get to the pan. Clean it out with a diluted bleach solution.
