Couple of days ago my ac stopped blowing cold air. vents had warm air coming out of it. I went to check the condenser unit outside and found that the fan and the compressor were not turning on. When the thermostat sends the signal, I can hear the contactor click but no buzzing noise. I thought it might be the Capacitor so I replaced it but it didn't fix the problem. I'm now thinking its the contactor. I noticed the middle of the contactor looks burnt out? How can I tell for sure? Can I test it somehow after turning off the power?

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  • I see the burnt contact you speak of. I’d just replace the contractor, I’ll bet it’s the issue, if it’s not now it will be sooner than later. I have a test method I’d use, but I wouldn’t call it safe for most people to try. – Tyson Jul 13 '18 at 0:17
  • I assume since you are still with us, you discharged the capacitor before trying to replace it. Unless it failed to charge, it can take some time for their charge to dissipate. Please call someone unless you fully understand what you are doing. A lot of people learn this lesson the hard way. – CBass Jul 13 '18 at 2:55
  • Yes. I discharged the capacitor before replacing it. However, I did not wait long before turning the unit on. I then put the old capacitor back in place since I thought it wasn't broken. I don't mind calling someone. I called about 4 places, 3 people told me they can do it until next weekend and one guy said he'll charge $300 for coming out then its additional $150 for every hour and this is without even knowing the problem. I have the contactor part coming tomorrow. I'll turn off the main and replace it and see if that fixes it. – Sam Jul 13 '18 at 18:30

it was the contactor after all. I replaced it and everything turned on just fine. After inspecting the old contactor, I saw it looked like a bug caused the burn. New contactor has a protective cover so bugs won't get in easy.

  • Checking the Contactor is simple. Measure the voltage with a meter - the Line In Side should have voltage, the line out side should have voltage only when the contactor is made and it should be roughly the same as the line-in side ~ -1VAC max. – Ken Jul 14 '18 at 22:29

Sounds odd but check that your fan doesn't have an issue with wiring or power supply I had the same issue earlier this year. The wire was simply not seated correctly on my thermostat control unit in my basement.

  • I don't think that's the issue compressor is also not running though. – Sam Jul 12 '18 at 21:59
  • I agree especially since he can hear the contractor – Tyson Jul 13 '18 at 0:07
  • yes I can hear it click. I can see the button getting pushed in on the contractor. – Sam Jul 13 '18 at 0:10

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