Helped Diagnose a Blown AC Capacitor


Hi everyone. Just wanted to share a little anecdote from my sense install. I’ve had mine running since the end of January 2017 and I just used my sense to help me identify an issue with our AC unit while I was out of town.

I am a bit obsessive and tend to check my Internet connected home devices regularly - so last night while away on business I noticed that I had some unusual activity on my historical power meter chart - large spikes to ~15kw that lasted for a few seconds at a time. Logging into my ecobee I noticed that while the ecobee thought the upstairs AC was running, it was not actually cooling - the temperature was holding steady and my upstairs AC/Heat Pump device was not running according to the Sense “bubble” view.

Long story short, the spikes corresponded to the ecobee calling for cold air from the AC, but a bad run capacitor kept the compressor from starting. The sense allowed me to pinpoint when the issue began - you can see at about 1850 hours the symptoms start where there is the large spike in electric load, but the compressor does enter its steady state. You can even see what looks like (to me at least) the rapid deterioration and failure of the cap as the AC unit attempts to start itself several times over the next few hours. The difference between that and the activity just 30 minutes earlier where both AC units were running fine was crystal clear.

I know that you have announced plans to include this sort of electrical “troubleshooting” in the future. It would be awesome if the Sense was able to automatically identify abnormal activity such as this- but even with a manual process I was able to alert my wife at home before she even noticed, identify the probably cause and fix this issue for $13 (the cost of the replacement cap). Thanks, Sense!


This is a super cool story @jason. Thanks for sharing!


@jason. I had nearly the same experience! Only problem was that I was out of town and had to work with the AC guy remotely to fix the problem. Looking at the charts and it just made sense. Inside blower was on, condenser wasn’t responding. Turned out to be a burnt out relay.