Problem: Freezer at -30 degrees F and Fridge at +20 degrees F (Defrosted entire system for couple days then 12 hours after turning it on these were the temps). This is air temperature of empty compartments. Also, after leaving it off for a day, I turned it on again and after 4 hours the freezer was at -20 degrees F (and fridge at +30 deg F). I have already replaced temperature control, evaporator fan and defrost timer. More details below.

Notes and specific things that have been done to troubleshoot:
1) Refrigerator was moved upright in a shaky truck for 1000 miles. Then was left unplugged and unused in a garage for about 9 months.
2) We started using it but noticed the fridge was too warm (40 degrees) but freezer was good. So we used the freezer only for about 6 months (and just left fridge empty).
3) Finally decided to try and fix. Removed the freezer compartment backing and discovered it completely frozen up.
4) Replaced defrost timer (only because I accidentally broke it when debugging this problem).
5) Discovered that evaporator fan motor was stuck so replaced that.
6) After replacing evaporator fan, noticed that the fridge was too cold at 20 degrees so replaced the temperature control.
7) Still thinking the problem was in the fridge, also checked the damper control which seems to be working (damper is opening and closing at different times).
7) At this point thought I'd also test the freezer temp and finally realized that the problem has to do with the freezer being too cold.

And this is where I'm now at a loss and needing assistance. What can be causing the freezer to be too cold?

Any help is appreciated! Thanks!

Yes, the sensing wire is attached and goes to the freezer vent.
The temperature control was replaced with Maytag Genuine Factory Part 61002043. What is part# AP4068700? I appreciate your help. Thank you so much! Continued assistance is appreciated. Evaporator Fan was replaced with Maytag Genuine Factory Part 69298-1 (but the part seemed a little different).

Again, Fridge model is Maytag MTB2156-DEB

First just want to say thanks for your assistance. I can tell that you're both knowledgeable and thorough. I like your debugging thought process and the additional possibilities to check.

Anyways, the Temp Control does turn on and off. Unfortunately I don't have a thermometer with sensing wire. Yet, from the physical looks, the fan in the freezer blows into a vent that goes straight to the sensing wire which is at the bottom of that vent (and at the top of the fridge section). There is clearly no obstruction.

Couple more questions, if I may:
1) How can an airflow problem cause freezer AND fridge section to be too cold? If just freezer, than I could understand it possibly being airflow. But I'm not sure I understand how airflow could cause both to be too cold. (Woke up this morning with freezer at -40F! and fridge at +20F)

2) Where (and what) is the lower air return? I didn't see any flaps or openings behind the crispers.

3) Why would light bulb on or reduced RPM's make freezer and fridge colder?

Thanks again. I'm really trying to work hard on this and sincerely appreciate your help!!!

pat

THANK YOU so much for your help! Because of your assistance, I was able to figure out that somehow the evaporator fan motor I received didn't work or wasn't the right one. I only figured it out because of your debugging skills and thought process of what might be causing it to never shut off. It's working great now. I think the motor I had received was probably spinning the other way which was causing the air to not be blown into the freezer. So again, THANK YOU, THANK YOU, THANK YOU! People like you who are willing to help others make this world a better place!