My side by side fridge is icing up on the freezer side, but the fridge side isn't getting any cold air. It's constantly running, and there isn't any cold air coming through the vents from freezer to fridge. I noticed ice buildup in the vents so I melted it with a hair dryer but the cold air still isn't coming through. I think the defroster isn't working. I haven't hear the water dripping into the pan in several days. The seal is fine, I checked that.

The freezer cools the refrigerator, so you actually get very cold air passing from the freezer to the refrig. The air from the freezer enters the refrig on the top and falls to the bottom where it is drawn back into the freezer. The temperature of the refrig is regulated by a thermostat and a fan that runs when the thermostat calls for cooling. If the refrig thermostat is faulty and causes the fan to run more than it should, there will be a freezing problem in the refrig at the bottom because cold air falls and warm air rises. If the refrig is thermostat is calling for cooling constantly, this will take more cold air from the freezer than is normal. Your freezer temp might be higher than normal and the refrig will be colder then desired. If the fan from the freezer is running constantly I would suspect a bad refrig thermostat.

ok,1st check on fridge side toward upper back of the top and feel for air coming thru, and there is another one down possibly behind crisper .I had this same deal. Had to do total defrost,, put food in cooler,, theres two blower fans in these types of fridges,,one in the bottom back,, and one in the back of the frezzer,, I used an old hair dryer and let it blow warm to top interior of frezzer,, careful not to let any cords hang/drop in any water!!,ok once done dry out as much water as possible, turn fridge on set both controls to 4,when fridge kicks on do the feel test,, you may need to close the frezzer door, air should be felt near top inside of fridge,if so than shut fridge side and feel inside frezzer near bottom and air should be felt,, side-by-side need to circulate air from frezzer to fridge, then back to frezzer

If the machine is running all the time a few things could be happening, The defrost timer could be bad, but if that is the case then you should see a build up of ice forming on the wall that covers the evaporator coils. Another situation is that your machine is low on freon and not reaching a temperature cold enough for the temperature control to shut the machine off. Third and last the temperature control itself could be bad and thinks the machine isn't cold enough. in that situation you would notice ice build up as well. Hopefully this helps.

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the door was left open,if you find frozen water droplets on the food packages or ice crystals it forms from the warm air coming in,make sure all the packages are pushed in and not hitting the door and you can tilt the fridge back a little so the door will close with a slight push.also check the ice shout door and make sure no air is leaking through it,you'll know you'll see all ice around it.you can check the condenser coil and condenser fan to see if it needs to be vacuumed,the machine will run longer if the coil is clogged with dust or if the fan isn't blowing,the coil should be cleaned every 6 to 12 months.hope this helps but it sounds like the freezer door was left open.

The fridge gets its cold air from the freezer through a vent(damper) between the freezer and fridge.The fan in the freezer blows air through it. Make sure this fan is running. You may have to hold the door switch in for it to run. There is a flap you adjust with the fridge temp. control. Make sure it's opening and closing when you adjust the fridge temp.
The problem could be the electronic control if you have one or the mechanical linkages.

If the evaporator coils behind the back panel of the freezer are icing up because of auto defrost failure that will stop the circulation of cold air and eventually affect the freezer too.

Are your evaporator fans working?

Since I am not there I can't take a look at it and tell you with certainty that this or that is the problem, but I can tell you a few things to check to localize the problem.

If the cooling fan is not operating, there is nothing that will force the even distribution of cold air, and since cold air falls, it would make sense that both the refrigerator and freezer sides are cold but the upper areas are not. So that is the first thing I would check, if it isn't working, then you will need to find out why.

A second possible is that something is wrong with your defrost circuit (probably timer) and your defrost heater is constantly on.

Either of these possibles could cause the problem you describe.

you may have a seal problem on your doors make sure all seals seat to the fridge body properly, I suspect moist air getting in the fridge or someone putting hot food in it after supper :-)

Sounds like your cooling fan is out. If the freezer is fine and the fridge isn't, then the cooling fan isn't blowing the cold air the the fridge. Or you could have ice obstructing the airflow.

open the freezer door,do you hear the fan blowing around?it sounds like the evap fan motor isn't running and that's why it's cold on the bottom and not the top,you have to repair this fast or you'll loose your food in the fridge,the fan is what blows the cold air from the freezer to the fridge section.

Listen for the fan motor to run. Open the freezer\ push the door switch with your finger \ listen for the fan that blows the cold air to the fridge. only the freezer side gets cold...fan blows cold to the fridge side. If the defrost timer has broken then ice may be blocking the flow of cold air to the fridge also. Only 2 things to check. Good Luck