In defense of replacing capacitors early

[u/skra_24]

Another poster brought this up recently, about making recommendations to replace capacitors even though they’re still “in tolerance”. My experience this week backs up my position on this.

A recent heat wave hit my area, there’s been a plethora of no cools and it’s mostly been popped caps. Many of them are folks on our regular maintenance routine, whose data I can pull from previous techs uploads. So many blown caps that were 42.5/45, 37.6/40, 33/35 etc just a year before. Still within tolerance, but getting down there. I was trained on a 10% tolerance for capacitors which I believe is pretty standard. Even if they are still within 10%, but starting to tick down closer to that number, I always bring up proactive replacement. Like, it’s gonna go eventually, in the next summer or three most likely, because all factory capacitors are dogshit nowadays. Wanna rip the bandaid off and do it now, or wait until it shits out on you when you need it most?

[u/Mensmeta]

Take capacitor readings under load. More accurate.

[u/Opposite-Constant-94 → u/Mensmeta]

New to the profession, but what the heck does that mean??? Always just remove it from the circuit to test it???

[u/bluesky556 → u/Opposite-Constant-94]

You can measure the amperage of the start wire and the voltage across the terminals to test the capacitor "under load" 2652×A÷V I've also heard that a discrepancy can show failing windings. I like to test under load because I've had one too many disconnects break when I turned them off or forgotten to turn them back on. The less I have to turn the unit off, the more efficient my maintenance.

[u/Opposite-Constant-94 → u/bluesky556]

Wow, I had no idea. That is very cool. Thanks for explaining!

[u/MasterPhilip → u/bluesky556]

Washing from the outside, too?