Hi I have a question I hope someone can answer for me, I turned my a/c off yesterday and opened the doors then when I turned it back on no cold air it was fine before, everything seems to be working fine exept a loud buzz coming from outside unit every 15-20 secs it sounds like something trying to turn on lights dim in the house a lil when it buzzes
IANAHVACTech: Sounds like your compressor motor is shot.
Try this: at or near the compressor (the outside unit), there will be a power shut-off. Shut it off, then find the breaker for the HVAC system (or possibly just the AC, I don’t know your system), and flip it off, then back on again, then throw the power to the compressor back on. It’s worth a try.
Is the fan coming on? You have central air with an outside unit, right? look into the unit when you turn it on, and see if the fan comes on. It sounds like it’s trying to come on, it draws a little to much power, which is what dims the lights, and then it gives up, because it has some fail-safe that makes it quit trying when it starts to get hot, or draws n+1 amount of current. After it’s been off for a certain amount of time, it tries to come on again. The fan can seize for a number of reasons, or something like a stick can fall in and gum up the works.
If the fan is coming on, then there is still some kind of relay or something that is failing, and you probably have a short somewhere. You need to call someone.
Fan working fine it does have the switch out back to turn it off but it wont switch to off for some reason I will try again
Before I turn breaker off for ac the power switch has to be off ? Idk why this thing wont flip to off its always worked fine its really hard should I hit the switch with something to make it go to off or not a good idea
You can try the breaker first.
Then it is probably the compressor, but it still could be something electric-- a short somewhere.
I’d need more information, but that sounds like the start capacitor for the compressor. It’s a $20 part but you need someone that knows what they’re doing to swap it out for you. In the mean time turn off your AC since it’s not going to start.
The corner of your outside unit pops off and you’ll see either one or two cylindrical things. Don’t touch them even with the power off, you short them out, after the power is off so you don’t die. Take if off, go to Grainger, get a new one, you’re set.
Based on nothing other then the OP, this is where my money is.
BTW, if the capacior has three wires, there’s a wiring diagram (probably on the panel) to tell you which wire goes to C, Herm and Fan, but if you take a picture it’ll make it easier to confirm it if the wires don’t match the diagram.
If you have a multimeter you can confirm that the cap is dead, but, like I said, I’ll bet it is just based on the noise.
If you want to do this alone, let us know and I/we can walk you though how to fix it, otherwise call someone who knows what they’re doing.
If you don’t have a multimeter, they are not expensive. You can get one at Walmart that is good enough to confirm that the part is dead.
I agree with Joey P that it is probably the start/run capacitor. It is certainly a cheap place to start. If it’s bad, the top may likely be swelled up and bulging, but not always. Keep in mind that some have separate capacitors for the fan and the compressor and some have a single, combined capacitor.
They can be as cheap as $20 but some are $50-60. If you don’t have a Grainger near you as he suggested (that’s where I got mine) Home Depot sells them too but you may have to order. You will probably not have any luck trying to get an A/C supply house to sell to you if you are not an A/C company from my experience.
Google for videos of how to swap it out, then watch a few and decide if it’s something you want to try yourself. Watch a few for sure since some show tips that others don’t.
It is very easy. And if you do it yourself, you’ll wonder why people ever pay $200-300 to have it done for them.
If that doesn’t fix it, then of course call a professional but you may as well leave the new capacitor in (if it’s compatible with whatever changes they make - new compressor, new outside unit, etc.) since it’s something that wears out every few years anyways.
PS - And I know this wasn’t your problem, but in the future if it was the outside unit fan that wasn’t coming on you can poke it with a stick when you hear it trying to start up. If the fan spins easily and then continues to work normally, it is pretty much assured that it is the start/run capacitor.
There is also a start/run capacitor for the blower motor for the inside unit (if that was the thing not working). The blower, of course, is what sucks your house air in through the return vents, blows it across the cold evaporator and back to the rooms. That one can be a little harder to get to and replace but is doable.
If you can not determine why the switch out back will not shut off go to the breaker and turn it off and leave the unit alone. You can hurt or kill your self if you are guessing on what to do with electrical equipment.
You may have some wirring problems or just a bad cap. but I would not guess.
I had a similar problem with mine and from a lot of internet searching decided it must be the capacitor. Took the side off the unit, removed the old capacitor, got a replacement, and… nothing. Called the HVAC guy in and he got it going, He said “Yeah, it was the capacitor allright. But there’s a secondary one further in the unit. That’s the one that was bad.”