HVAC system stopped blowing cold air today. Last time it did this, we gave it a 2-3 hour break, in case it was over-heated, and it came back. Today, same deal, but no cold air after a few hours. I went out and didn't hear the compressor or fan going.

After opening the unit to have a look, I noticed that 1) the capacitor had "goop" over it (see circled sections of pictures below) 2) the electronics "bay" looked a bit wet, which was odd (see top of picture #1 below). I suspect this is a sign of a blown capacitor, but GoogleBing image searches aren't conclusive. Suggestions? Opinions? Conclusions?

Exhibit 1

Exhibit 2

  • 1
    Once the goop comes out, it's time for a new one.
    – Tester101
    Commented Oct 11, 2014 at 13:02
  • Smoke and goop, both signs of electronic death, it's dead. Commented Oct 13, 2014 at 15:32
  • Replacing the capacitor was indeed needed, however, it turns out that the breaker in the main breaker box (not the outside cutoff) was defective and needed replacing as well. I suspect that one took out the other (breaker the capacitor, or capacitor the breaker). Hopefully, having both be new will help, and glad I found an "open to the public" HVAC supply store open on Saturday!
    – Hugo
    Commented Oct 13, 2014 at 18:55

1 Answer 1


The capacitor needs replacement. While it is possible there is a circuitry problem causing the capacitor to overheat (and thus fail like this), it is also possible it was simply time for this electrolytic capacitor to fail while nothing else is wrong.

See this photo for a similar failure mode.

  • It's only about 2 years old, but at the same time as it's gone out, there was a light flicker. Now we need to determine whether the flicker was caused by the capacitor, or the capacitor failure by the cause of the flicker.
    – Hugo
    Commented Oct 11, 2014 at 17:51
  • @Hugo: That's unfortunately new. It is new enough to expect many more years of trouble-free service, but old enough for the warranty to have expired.
    – wallyk
    Commented Oct 11, 2014 at 18:20
  • Very true @wallyk. I suspect the batch may have been bad, since that was the second replacement (back then) within a few days, as the first one went out (failed after running 20-30 minutes) the day it was replaced. So one bad "out of the box", other one blows within 2 years? At least these new ones are different brand, and made in Feb this year, so probably not the same batch!
    – Hugo
    Commented Oct 13, 2014 at 18:58

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