Had a checkup on my AC/ furnace a couple weeks ago. The technician said the capacitor leaking oil and not pulling enough amps. He recommended me getting a whole new system. (My house was built 6 yrs ago.)

I said no I cannot afford, he replaced the capacitor. I asked so you tested and the amps are all good now. He responds that he did not test anything after he replaced it. That struck me as odd but what do I know I'm just a woman.

Since replacement, the lights dim when unit kicks on, which it has always done that, no worry. While unit is running the lights will dim several more times. Each time they dim there is an audible pause in the operation of the unit. Very very short pause like of about a second. This worries me. I would be very appreciative of what could be the issue and what I should check on my unit.

  • Is the fan on the outdoor unit spinning?
    – Tester101
    Jun 23, 2015 at 17:38
  • Could be that they installed the wrong capacitor, but there's no way to know without knowing the make and model of the unit, and the rating of the new capacitor.
    – Tester101
    Jun 23, 2015 at 19:04
  • Yes the outside unit is operating. He said that he used the same size capacitor as what he took off.
    – Renee
    Jun 24, 2015 at 1:27
  • Sounds more like e bad contact or a defective protection or motor control of some kind. A bad motor capacitor will prevent the motor from starting or make it run rough.
    – Dan
    Jun 24, 2015 at 18:40

2 Answers 2


If the lights are dimming several times while the unit is running, the only thing you can check is listen to the outdoor unit to determine if the compressor is unexpectedly starting and stopping when it should be running continuously. Set the thermostat to a low setting and listen outside to see if you can hear the compressor starting and stopping at about the same interval as you notice the lights dim.

If abnormal starts and stops are occurring, a competent technician is needed to evaluate and repair the problem. Whether or not the compressor is cycling unexpectedly, installation of an appropriately sized 3 wire hard start kit can sometimes alleviate lights dimming on startup due to the electric service being marginally small for the unit.

You may want to try a better technician than the one who advised an entirely new system and then replaced a leaking capacitor. Any technician worth his salt would use a capacitance meter and not an amp meter to legitimately investigate this problem. Also, unless your 6 year old system was installed absolutely horridly, it should not need replacement so soon.


Each time they dim there is an audible pause in the operation of the unit. Very short pauses, like of about a second.

Sounds like a chattering contactor. Causes may be from scorching on the contacts or from too low a voltage to pull it in properly.

Replace the batteries in your thermostat. Inspect all of the contactors in the condenser, if you are electrically inclined.

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