September 9th, 2015
I PERFORM A POST MORTEM ON A KITCHEN-AID REFRIGERATOR COMPRESSOR INVERTER
Lately, I’ve been seeing more inverter failures on inverter boards, especially on Kitchen-aid brands. An inverter is simply a device that takes 120 VAC in, then converts it into a DC voltage and chops it up into 3 phases. It’s there to make the EPA happy since they feel that our older style refrigerators with AC compressors are just too in-efficient.
The inverter refrigerators use variable speed compressors, so that the speeds vary according to the heat-load in the box. Ideally, such a compressor would run almost continually as a low speed setting to maintain correct temperature.
Here’s the inside of a typical inverter:
Of course, looking at the plastic case these electronics are encased in would give you no clue as to what happened, but if you were to open it up this gives an idea what’s up inside.
There’s a few ways to verify if the inverter has gone bad; First, is there 120 VAC to the inverter? Second, is there anywhere between 3 to 12 VDC to it? Third, do you have continuity of approx, 7 ohms between all 3 pins on the compressor? If so, its a pretty sure bet the inverter is bad.
These boards go from anywhere between $150 and $275. Conversely, if your refrigerator uses and older style AC Compressor, a typical start device (the counter-part of an inverter) is about 60 bucks. Its not as efficient as an inverter style box so you can expect to pay about $20 bucks per year to run it.