Why is the bottom vent in my kenmore coldspot fridge freezing

Remove the front panel at the bottom of your fridge. There will be a tray that you can remove, it is probably full of water. That's ok just dump the water clean the tray and replace it and the front cover. If the problem continues you might need to clean the door seals.

If further adjustments cannot be made to the thermostat, the next step would be to replace the thermostat or if so equipped, the temperature thermistor.

there is a flap in the refrigerator side usually near or behind the light bulb the freezer side is thermostatically controlled with the compressor being controlled. On the refrigerator side the cold air comes from the freezer side. when this flap is open the refrigerator will cool continuously, Check the flap or the duct assembly
here is an illustration of the part
http://www.repairclinic.com/Kenmore-Refrigerator-Model-10674219400-ID-927868-Duct-Venting-Parts

Is the compressor working? Check to see if it is hot.

you dont need to lower the temp. if everything is freezing at the bottom of the fridge, and not the entire fridge compartment, then your problem is your freezer fan, or evaporator fan, is failing to circulate the air clockwise through the unit, you need to replace that fan motor.

its not defrosting. check heater operations. bimetal near heater. check defrost timer

I think the thermostat is faulty. Thus it makes the freezer extra cold. Try replacing it. Regards, Nandini.

Either the freezer continues to freeze up (most likely due to low refrigerant, due to a leak), or there is an obstruction between the freezer and the refrigerator (refrigerators get their cooling from the freezer).

Given that it works after you defrost it, I'm going with low gas. Call a professional to see if the leak can be fixed. If the unit is more than 10 years old, just get a new one.

You're frozen up.  Defrost completely.  Then, clean your condenser.  Make sure to never leave open containers in the fridge...water condenses into ice.  If you still have problems, you may be low on gas.