Lennox furnace short cycling in the summer with the AC on?

Old 08-21-15, 08:37 PM
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Lennox furnace short cycling in the summer with the AC on?

new home owner here and still learning all I can.

I live in a brand new home. We built it and moved in about 14 months ago. We have a Lennox furnace and I'm not sure the brand of AC because it is dark outside right now.

The furnace was making a strange knocking noise. Eventually it stopped knocking and started to run. There is condensation on the outside panels of the furnace and some water pooling on the floor (maybe 1/2 cup at the most).

The AC is on and set to 74 while the furnace is set to auto which I believe will allow the fan to blow the cold air from the AC through the ventilation system. This is normal right? Without the fan on, the AC would just allow air to seep into house which would take longer to cool the house leading to it running longer and more often.

Just a few minutes later though, furnace turned on again and then turned off in a matter of 2-3 seconds. Then would repeat that about 7-10 more times.

It is 10:30pm so I'm not going to be able to call someone now but if I need to, I want to as early as possible tomorrow morning.

Old 08-21-15, 09:29 PM
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If the blower stops working..... the cold air will not seep thru the house and the coil will freeze up with ice.

It sounds like you need to investigate the furnace blower system. It almost sounds like you have a belt driven blower with a bad belt. You can remove the bottom blower service door and check things out.

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