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Home AC was running, and then I heard a loud noise from the compressor, and the compressor fan stopped spinning. Of course after that the fan in the basement was still shooting room temperature air out of the vents, but not cool. I noticed that after the explosive sound the compressor unit was humming buzzing; fan no longer turning.
Symptoms:
1. AC compressor humming buzzing
2. AC compressor fan not spinning
This generally means that the capacitor has blown. Not sure why this happens, but the solution is to simply replace it. You may also do a quick further test to make certain that it is the capacitor, by poking a stick into the compressor vent at the top, and giving the fan a push. If pushing it gets the fan rotating, this too is a symptom of a blow capacitor. But in almost all cases, compressor humming but fan not spinning means blown capacitor.
Turn off all power to the AC unit either at its independent circuit breaker, if it has one, or by pulling out the module in the AC disconnect which is in the wall near by the compressor.
Access the service panel. To do this, you might need to as well unscrew the entire top of the compressor unit, which is connected to the fan. No need to remove it completely just lift it up enough to be able to access the service panel cover, and unscrew it, and remove the panel.
There will be a capacitor in there somewhere. There are two different types found in ACs, either start or run capacitors, but for purposes of diagnosis and replacement, you don't need to know the difference other than to make sure whatever you put in there to replace the blown capacitor is the same as whatever you take out.
In my AC unit, which is a smaller one for a guest house, there is a dual-run capacitor. It is cylindrical.
You may use test equipment, if you have it, to test the capacitor, but basically if the top of it is blown out like a soda pop can that has been shaken, you may assume it is shot.
Write down or take a clear picture of the type of capacitor it is, in my case a 35 / 5 uf 370 VAC, and to keep it simple just google some of the numbers on there, for example in my case "97F9834 capacitor" and you will figure out what you have. I found out that mine is a
dual run capacitor 35/5 uf 370 volt
After googling these terms, I found a replacement dual run capacitor for about nine dollars delivered. The upper (35) and lower (5) uf must be the same, and the voltage rating (370 VAC) the same or higher. And of course it must be the same type of capacitor, with same arrangement of leads.
It's okay, as long as it's a dry season and not raining, to just leave the service panel open while you wait for the part, I recommend leaving the blown capacitor in place with its wires connected, until the replacement arrives.
At any point before you touch or remove the old capacitor, be sure to discharge any voltage that might remain in the capacitor by touching a metal screwdriver stem, being careful to hold its insulated handle only (and NOT touch any metal), across the different terminals of the capacitor.
When the replacement capacitor arrives, simply unplug the old one, one lead at a time, and hook up the new one. In my capacitor there were certain terms by the leads such as "fan" and "herm" that also guide you to make certain that are connecting the leads properly, same as before.
Re-clamp the old capacitor down, line up the service panel and the compressor top and fasten back all screws. When you reconnect power and turn the AC back on, your compressor should be back to spinning as usual and supplying the cold air you expect.
Symptoms:
1. AC compressor humming buzzing
2. AC compressor fan not spinning
This generally means that the capacitor has blown. Not sure why this happens, but the solution is to simply replace it. You may also do a quick further test to make certain that it is the capacitor, by poking a stick into the compressor vent at the top, and giving the fan a push. If pushing it gets the fan rotating, this too is a symptom of a blow capacitor. But in almost all cases, compressor humming but fan not spinning means blown capacitor.
Turn off all power to the AC unit either at its independent circuit breaker, if it has one, or by pulling out the module in the AC disconnect which is in the wall near by the compressor.
Access the service panel. To do this, you might need to as well unscrew the entire top of the compressor unit, which is connected to the fan. No need to remove it completely just lift it up enough to be able to access the service panel cover, and unscrew it, and remove the panel.
There will be a capacitor in there somewhere. There are two different types found in ACs, either start or run capacitors, but for purposes of diagnosis and replacement, you don't need to know the difference other than to make sure whatever you put in there to replace the blown capacitor is the same as whatever you take out.
In my AC unit, which is a smaller one for a guest house, there is a dual-run capacitor. It is cylindrical.
You may use test equipment, if you have it, to test the capacitor, but basically if the top of it is blown out like a soda pop can that has been shaken, you may assume it is shot.
Write down or take a clear picture of the type of capacitor it is, in my case a 35 / 5 uf 370 VAC, and to keep it simple just google some of the numbers on there, for example in my case "97F9834 capacitor" and you will figure out what you have. I found out that mine is a
dual run capacitor 35/5 uf 370 volt
After googling these terms, I found a replacement dual run capacitor for about nine dollars delivered. The upper (35) and lower (5) uf must be the same, and the voltage rating (370 VAC) the same or higher. And of course it must be the same type of capacitor, with same arrangement of leads.
It's okay, as long as it's a dry season and not raining, to just leave the service panel open while you wait for the part, I recommend leaving the blown capacitor in place with its wires connected, until the replacement arrives.
At any point before you touch or remove the old capacitor, be sure to discharge any voltage that might remain in the capacitor by touching a metal screwdriver stem, being careful to hold its insulated handle only (and NOT touch any metal), across the different terminals of the capacitor.
When the replacement capacitor arrives, simply unplug the old one, one lead at a time, and hook up the new one. In my capacitor there were certain terms by the leads such as "fan" and "herm" that also guide you to make certain that are connecting the leads properly, same as before.
Re-clamp the old capacitor down, line up the service panel and the compressor top and fasten back all screws. When you reconnect power and turn the AC back on, your compressor should be back to spinning as usual and supplying the cold air you expect.