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Mike, Home Appliance Technician
Category: Appliance
Satisfied Customers: 17629
Experience:  I have been repairing appliances for 25 years, I run my own appliance repair business.
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Viking refrigerator/freezer not cooling. We have a Viking model

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Viking refrigerator/freezer not cooling. We have a Viking model VCBB363RSS that has been a problem for a while.

The original problem was that the moisture would build up inside the freezer chamber so badly that it would freeze over the drain hole and eventually the freezer would just shut down and water would leak all over the floor. The Viking "service" people chipped off a plastic lip around the drain hole and that seemed to fix the problem.

The new problem is that the freezer is now frosting up on the back of the freezer within 24 hours after defrosting (1/4" thick ice in 24 hours). It is also making ice very slow and the cubes are hollow. We lose power quite often, not sure if that brings it back to default settings that are not cold enough. The fridge only gets down to forty degrees at coldest. It is also in Key West so the humidity is very high.
Hi the problem is with the defrost system. You will need to test the heater and defrost thermostat with an ohms meter. Both should read continuity, it the heater or the thermostat reads open you should replace it. Make sure when you test the thermostat there is still frost on the evaporator since it needs to be below 30f to show normal operation. If you have any questions please feel free to ask. Mike
Customer: replied 6 years ago.
Where do I put the prongs of the Ohms meter to test continuity?
Disconnect the heater and the thermostat, they should have 2 wires. Put one prong on one wire and the other prong on the second wire. Then test for continuity, if you get no reading (open) it's your problem. Mike
Customer: replied 6 years ago.
Ok. I'll give it a try and let you know. Thanks!
Ok if the defrost heater and thermostat are good then the problem is with the defrost timer which is built into the mother board. This would mean you need to replace the mother board.
Customer: replied 6 years ago.
Ok so the defrost thermostat and defrost heater both tested with continuity. So you think the motherboard is the next best possibility? We lose power quite a bit at this house. Is it possible that that would affect the circuit board? Would it be worth putting a small battery backup on the fridge?

Also do you have any idea where the circuit board would be found on that Viking fridge?
Hi, unfortunately Viking do not give access to schematics so it is tough for me to figure out where the motherboard is. If this is a built in model it will be behind the grill at the top, if a free standing either behind a panel at the rear or in the control panel inside the unit. if the defrost heater and defrost thermostat are good then the only other problem will be the mother board. If your power goes out often it's likely the board would short from a surge. A back up would not help but some kind of surge protection would like putting it on a GFI or similar. If you can't find the mother board contact Viking customer service, they should be able to help you locate the timer/motherboard. Mike
Customer: replied 6 years ago.
We are in progress installing the new parts today. We are just replacing all 3 (defrost terminator, circuit board, and defrost heater). One thing we noticed is that the local Viking service people already pulled out the defrost terminator (since it had wire nuts on the wires where they sliced it back in). But inspection of the wiring diagram showed they wired it in backwards (It was supposed to go brown to brown/orange to black and instead they wired brown to black/orange to brown. Do you have any idea what would happen if the defrost terminator were wired in backwards?
Hi nothing should happen, it's either a bi metal or a resistor. Should be able to wire it either way.
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