Model Number: KSSS42DBW00
, this refrigerator failed for the customer sometime during their vacation resulting in the usual loss of food and water from melting ice everywhere. There were no interior lights, fans, or anything else working on this unit indicating no power or at least an open circuit. Normally when trouble shooting this kind of problem, I start at the power source (wall outlet) but because this is a big built in unit, I though I would try something a bit easier to get to.
Knowing where to Start
If you are unfamiliar with most large scale built-in refrigerators, take a look at the tech sheet and you will notice a power cut-off switch usually located with the system components behind the top grill piece. This is a nice feature to have available since most of these refrigerators are plugged in from the rear and would require them to be un-installed just to check source power. Figuring I would start here for my trouble shooting, with meter in hand I accessed the switch terminals by removing the airflow grill from the housing. What I found was visible damage to two of the switch terminal connectors, and most likely the switch itself.
Switches have Types?
This switch is a DPST (Double Pole Single Throw) meaning there are two independent poles being switched (Double Pole), and they can be either on or off (Single Throw). What this allows is with a single throw of the switch, both the hot (L1) and neutral lines from the power cord are switched on or off completely isolating the unit from the house power and making it safe during servicing. The unfortunate part is either set of poles can fail resulting in an open circuit and a dead refrigerator.
Which is exactly what wad happened here. By taking a quick voltage measurement at the switch, I found my AC source voltage on the input side, but nothing on the output meaning this switch was an open circuit. A quick look inside the switch itself indicated that it had been subjected to some excessive heat for some time and finally just melted to the point the contacts no longer touched. This is usually the result of a loose terminal connector causing excess resistance and where we have electrical resistance, we have heat. By replacing the switch with a new one, and replacing both of the damaged connectors, this refrigerator was back cooling after it's own vacation.