Recently our AC stopped working. The thermostat is working properly, but the unit just started blowing hot air. I've never worked on a AC before, but I was trying to save some money. Anyway:

I started with replacing the capacitor on the unit, after completing that I turned the power back on but still nothing. I pushed the plastic piece in on the contactor and the unit came on, to include the fan. Once I released it the system shut off again. I went inside and checked the breaker box and noticed that two fuses had blown, replaced them and went back outside to see if the unit was running and it was for about a minute then it stopped. Fuses had blown again.

I asked a guy at the AC parts place and he said it could be the fan motor, but he also said it may be the contactor. I replaced the capacitor, fan motor and contactor. The new fan motor had 4 wires and the old had three. Brown, brown/white, black and yellow wires. Instead of using a dual capacitor for the brown and brown/white wires I just capped the brown/white, attached the brown to the F on the three prong capacitor I installed earlier and connect the yellow to the C and the black the line 1 on the contactor.

I made sure everything was secured and all plugged in. Everything looked good and I replaced the fuses in the interior breaker box. Turned the main power on outside, but nothing, fuses did not blow on the inside and thermostat was still working inside. I can't figure it out. Any ideas?

  • 5
    I've never worked on a AC before, but I was trying to save some money. Hmm - An actual A/C service person would possess gauges, tools and knowledge to actually find out what's not working, where you seem to have been throwing parts at the problem without any real diagnosis; which sounds expensive to me.
    – Ecnerwal
    May 13, 2015 at 20:43
  • 1
    The peanut gallery is in rare form today.
    – Edwin
    May 14, 2015 at 2:06
  • 1
    Was the existing capacitor the same size required by the new motor? Often times when replacing the fan motor you have to install a new capacitor just for the fan motor, because the existing capacitor is not the proper size. Did you test the contactor to make sure it's still good? Did you check to make sure the system is signalling the condensing unit properly?
    – Tester101
    May 14, 2015 at 11:18
  • Did you follow a writing diagram on the motor, or how did you figure out to just cap off the brown/white wire?
    – Joel Keene
    Dec 15, 2015 at 5:32
  • I don't know where you're at now, having futzed with it, but I've answered what I think was the original problem. Also <cough> don't call that guy again...
    – Mazura
    Jun 11, 2016 at 17:00

2 Answers 2


Sounds like a blown compressor.

Bad contacters don't usually pop fuses. And if it was simply the fan not coming on, the compressor should trip its own over-heat, not your breakers (unless it's old and grumpy: same prognosis; dead compressor).

If I were to keep trying to fix at that unit, the first thing I would do is install a "fused" (circuit breaker) disconnect for the condenser outside and a convenience outlet (both are now required by code).

That's step one of installing another unit, so it's no big loss if that doesn't help the diagnostics.

Air Conditioner Not Cooling : Tripping Breaker And Blowing FusesYouTube

My suspicion is we've got a bad compressor. Let me go grab my multimeter and get this thing tested out. Again, I'm going to go ahead and discharge the capacitor and then pull all the leads off the compressor. Then I'm going to go ahead and leave the fan motor connected and test. If this doesn't blow the breaker then that means our compressor's bad and it's time for either a new compressor or as old as this unit is, it may just be time for a whole new unit.

... It is as I suspected; the compressor's got a short in it. We're going to need either a new compressor or a whole new condenser unit. If I wanted to, I can recycle the fan top, the fan motor, and fan blades. That's a little bit more advanced troubleshooting and proving that it's actually our compressor that is down. We can replace the compressor if it's a clean change out. On this one, I think it's probably just maybe time for a new unit.

I've replaced compressors on commercial units (whose construction is conducive to such); it's not a very common practice for split systems, because that's the same amount of work, and you'd still have old equipment throughout.


Sometimes if the pipes are frozen might cause this. just turn it off for couple of hours (at least 3), and turn it again and see if this well help.


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