Original message
| Tuna Tataki
 |  "Lennox 10ACC -24 AC Unit Help..."
, posted Fri 9 May 18:12  
Need some help with this AC unit...it about 3 years old. Turned it on for the first time this year. The t-stat hits the specified temp and the fan kicks on. But for some reason it makes a noise every 6-8 seconds like it's trying to engage something like the compressor. The noise lasts for a second or two. It will do it like 5 or 6 times and then finally the compressor will kick on and it will blow cold air and everything seems fine...no other noises and it cools the house. It will cool down shut off and when it starts back up, it may do it again, it may not...meaning the fan and compressor come on together. I took a look at the schematics for this unit and manually engaged the contactor capacitor and it will make the same noise (like it's trying to engage the compressor) for a few cycles and then compressor will kick on and start cooling. Does the compressor have a capacitor on it that could go bad? I was advised that it maybe the start capacitor or the run capacitor. Is the start capacitor the same at the contactor capacitor? Is the run capacitor on the compressor unit itself? Is this capacitor (unit on compressor if there is one) a servicable unit or does the whole compressor have to be replaced?
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Replies:
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| TnNATE1412
| "Re(1):Lennox 10ACC -24 AC Unit Help..." , posted Fri 9 May 21:24
The system does have a dual run capacitor (meaning it works the fan motor on one side and the compressor on the other), which will be silver metallic. If the wire terminals on the top are arched (domed up) it is bad. The start capacitor and relay are field installed options. The start capacitor will be a round, black with only 2 wires attached. Look for white streaks running from the terminal end, indicates bad. If a start relay is installed, it will be about 2-3 inches square, black and have only 3 wires attached to 5 terminals. There is no way for a homeowner to check the relay. All of these will be located inside the coverplate of the outdoor unit. You can also have bad connection on the contactor that would cause the same symptoms. If in doubt, call a professional to check the unit.
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| | Tuna Tataki
| "Re(2):Lennox 10ACC -24 AC Unit Help..." , posted Fri 9 May 22:39
Thanks for the reply. It does not have a starter capacitor from what I can see under the control box cover. All I see it the silver cyclinder (dual run capacitor) and the contactor capacitor. I'll check the wire terms in the morning to see if they are arched up. Where would the relay capacitor be installed? In the control box area? Or near/on the compressor?
I guess I can try to clean the terms on the contactor capacitor (after shutting of the power to the unit of course) and reattached the wires to see if that does anything? Or are you saying the actual tabs that hold the ends of the wires can go bad?
Thanks...
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| | TnNATE1412
|  "Re(3):Lennox 10ACC -24 AC Unit Help..."
, posted Sat 10 May 06:34
No, the contactor points where you would press in, can become pitted or have something under them, bugs for example, that would cause the fan only to run because it does not require as much power to operate. A bug in the contactor will pass enough voltage for the fan to run, but not give the compressor enough voltage to start at times. If the unit does not have a start capacitor, it will not have a relay. The air conditioning condensing units only come with a contactor and dual run capacitor.
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