Where do I find defrost thermostat maytag rtd19a

You have one or more of your defrost components that are bad. Defrost heater, defrost thermostat, and defrost timer or board depending on model are the 3 components.

Could be the thermostat or defrost thermostat.

you will not be able to initiate defrost if its not defrosting the problem is one of three things.
control board, defrost heater and defrost thermostat can be found here http://www.repairclinic.com/Shop-For-Parts/a4b4d888747/Model-MFI2569VEQ2-Maytag-Refrigerator-Parts?RCAID=35836
Appliance 911
http://appliance911seabreeze.com

dont think both issues are related? the for the freezing up problem you need to check with a multimeter ur defrost timer and ur defrost terminator or AKA defrost thermostat as for ur ice maker? there may be a thermostat or circuit gone bad?

It looks like you have a defrost problem. It could be blocked air vents but I think there is a problem with either the drfrost heater or defrost thermostat. It cound be the defrst timer or control but i would check the heater and defrost thermostat first.

Defrost thermostat, defrost timer or defrost heating element is bad. Because of that the evaporator is clogged with ice and the cold air cannot get to the fresh food section. Therefore the thermostat control doesn't get cold enough to turn off the compressor. On the other hand the temperature thermostat may be bad and stuck inn the on position causing the ref to operate continuously thereby defeating the defrost cycle. Uplug the ref and allow it to thaw completely. (24hours). Then while its quiet... turn the thermostat to OFF or 0 and then to the coldest setting and listen for a click sound. No click sound means bad thermostat. Later after thawing plug in refrigerator and observe function after 2 hours and check for cold air flow to the fresh food section. If the refrigerator appears to be okay... the problem is a defrost issue. Most typically a defrost thermostat is bad, but when behind the freezer panel is a good time to perform an ohm/ continuity check on the defrost heating element.

Good day,
You have to remove the rear panel in the freezer compartment. The thermostat is clipped to the top of the cooling coil. Fairly simple job.
Here is a picture of one style..

It could also have a bad defrost heater. The heater and defrost thermostat are located mounted on the evaporator coil and the timer is usually mounted in the control panel with the control thermostat or in the compressor compartment.

This link will provide you the answer

http://www.appliance411.com/service/date-code.php

To access the heater circuit you must remove shelves from freezer, defrost the back panel with a hair dryer. Remove screws holding the panel in place and remove the panel. Defrost any ice on coil. This will give access to the heaters and defrost thermostat. If the defrost thermostat is deformed in anyway such as bulging at the molded part the chance is that that is your problem. Reading through the heater circuit with an OHM meter will tell you if the heater(s) are open. If you get an open reading replace the heaters. If this is above your capabilities call a service tech.