Maytag refrig (Model # MTB2156DEW) has puddle of water at bottom. The drain is fine and there is no frost build up. I would appreciate any help. Thank you

On the inside? There may be a drain there where it goes into a pan underneath the fridge. That seems normal from defrosting.
If the puddle is underneath the fridge, your pan may be clogged up.

Sorry, I wasn't real clear. The puddle is on the inside bottom just below the crisper drawers. I removed the back panel inside the freezer and there is no ice build up. The fan does come on and seems to be doing what it's supposed to. I'm wondering if the thermostat is bad. I would really appreciate any help. Thanks.

I've looked at a use and care manual from the maytag site and could not determine this for sure, but there should be a plug down there to let condensation drip into the pan underneath the fridge.
This may sometimes happen if you have just bought a lot of food and put it in, or your defrost drain is plugged. If it's cycling OK and cooling everything I'd think there is nothing the matter with the thermostat. Also, in hot humid weather it's possible to see this, especially if the door is opened a lot.

Thank you for responding. This has been going on now for about 2 months. The drain seems to be working OK and there is water in the pan underneath the refrig.