How can I get water to leak out from the rear so the vent don't freeze up?

Could be a leak in one of your hoses under the hood, a water pump gasket, thermostat leak or bad heater core. Check under the hood for any signs of leaks. If antifreeze drip onto a hot engine block, you’ll smell it coming in through the vents. If you don’t find any leaks, I’d consider the heater core having an issue possibly.

the drain tube is most likely clogged. if the lower vent is freezing up there is no way to confirm because it is covered with ice. the reason water leaks onto the floor is, the refrigerator goes into defrost, frost melts and runs down the ice to the door. use a hair dryer to remove all ice, then use hot water to check drain. drain tube may be up to a foot long and may have a trap. you may have to go in through the back to gain access to the drain

It's unfortunately the heater core that's leaking. It's very involved to replace it if you have mechanical aptitude, you can change it yourself to save money.

Freeze plugs in each head as well as in the block will leak over time. Don't just replace one...replace them all or you will keep having leaks as each freeze plug rusts through enough to leak.

have a water tank or line leak for water dispensor

The drain is clogged. When the drain clogs it can also clogs the airflow vents. Remove the back wall of the freezer to access the drain. Remove all the ice blocking the drain and the vents. Then use a trukey baser to force hot water down the drain until water flows freely. Then mix water with baken soda and pour it down the drain. http://www.appliance-repair-it.com/refrigerator-leaking.html

need to drain fluid and refill with clean oil.

defrost problem , call sears

I'm not an expert, but I took my 2000 Lincoln Nav to the shop and they told me the issue is that my accuator is not opening properly to allow the heat to go through; therefore, it's overheating. That's why I can feel some heat on the front in the back. All vents, including the rear vent blows strong, but they blow very cold.

Unfortunately, I'm also having an issue with my engine intake manifold or intake gasket being cracked causing anti-freeze to leak out of my tailpipe and smell badly through the vents - even on defrost - so until that's fixed, I'll never have heat.

The PUF Insulation is not suffecient or totally damped and need replacement to stop the water formation. Keep the fridge in a well ventilated room and not in a closed room. Due to high humidity the water formation takes place. Defrost the unit if there is excess ice so that cooling effeciencey could be instantly improved and the water formation could be to the minimal