Msf-49nm freezer will not go below 34 degrees farenhight

no they us a thermostat to operate temprature

The compressor runs during defrost to supply hot gas to the inside coil

Change the temperature control.

http://www.acmehowto.com/howto/appliance/freezer/repair/tempcontrol.php

Hi, Please set your thermostat a bit warm and observe the compressor. Also check your freezer for leaking.

http://www.turboairinc.com/TB-Service/Service%20Manual%20%20-%20April%202008/MSF-23NM.MSF-49NM.MSR-23NM.MSR-49NM.MSR-23G-1.MSR-49G-2.pdf
this web address should take you to the manual for your unit. check the settings on the controller first. If that does not resolve, let me know.

get a sheppards hook a parts store can help you tell them your prob

here you go: http://www.turboairinc.com/TB-Service/Service%20Manual%20%20-%20April%202008/MSF-23NM.MSF-49NM.MSR-23NM.MSR-49NM.MSR-23G-1.MSR-49G-2.pdf
takes alillte to load so be patient
hope this was helpful

http://www.turboairinc.com/TB-Service/Service.html#SOLID_DOOR_REACH-IN
Since I do not have the exact model number, here is the site you need to visit to get the manual. Hope this is what you are looking for.

My next question is, you say you have to call a tech to come out. Is he doing something? And if so, what? With the limited info I have at this time, it sounds like there may be a refrigerant problem. Let me know so we can continue. Am looking forward to resolving this.

I deal with MasterBilt which is a private lable made by TurboAir.
I have several units but only one does this icing up thing. Look for a bad seal on the door gasket. These really ice up if that does not seal almost perfectly. Look for premature termination of the defrost cycle. Check that the heater is pulling amps. The wiring diagram at "turboairinc.com" is very poor but it shows 2 heaters for the refrigerator. They list a diagram for the freezer but it's not there. I know for sure that there is a heater for the evap but don't know about the drain. I've seen some have it and some don't. there tech support line has much to be desired but it's worth a shot. Also, the bottom hinge on the door fails fairly regularly. This allows the door to drop just enought to disengage the switch at the top of the door and stop the evap fan from running, thus causing a freeze up.
Good Luck . You got your hands full with this one.