Spent 3 hours chasing a bad capacitor on a fridge compressor start relay

I had a Whirlpool fridge that kept clicking every 30 seconds and finally broke down and replaced the start relay assembly. Turned out the capacitor was fine, but the spade connector had a hairline crack that only showed up under load. Anyone else ever waste a whole afternoon on something that simple?

4 comments

4 Comments

robertgreen2mo ago

That phrase "hairline crack that only showed up under load" - did you find it with a multimeter or just by swapping parts?

wyatt522mo ago

Oh man, that brings back memories. I had a similar issue once with an old refrigerator compressor that would run fine for hours then just quit. I spent weeks swapping parts before I figured it out. What finally worked for me was something simple. I got out a magnifying glass and a bright flashlight and just slowly looked over the whole control board, especially around the solder joints. Found a tiny crack near a relay pin that I had missed three times before. A quick dab of solder fixed it right up. So if you ask me, and I know this sounds old school, sometimes the best tool is just your eyes and a good light. @robertgreen, you might try that before you swap too many parts.

uma6851mo ago

Multimeter trick is the way to go. I had a laptop power jack that would only cut out when the cord got pulled sideways. Flat on the table it tested fine every time. I started propping the board up at different angles with a pencil under one corner and testing continuity, and bam, soon as I tilted it the right way the meter went open. The crack was so small you couldn't see it without a jeweler's loupe, but the flex from the tilt was enough to separate it. Saves you from just swapping parts blindly, which I've definitely done way too many times before learning this.

ben2061mo ago

Used a multimeter actually, but not how you might think. I checked continuity across the suspect trace while flexing the board slightly with my thumb. Soon as I put a little pressure on it, the reading went from steady to open. That was my aha moment. If you just test it flat on the bench, it reads fine every time. You gotta mimic the physical stress it sees when everything heats up and expands a bit. Pain in the butt to find, but once you know the trick it saves hours of guessing.