Latest Discussions : HVAC

calgin

08:20PM | 08/31/09
Member Since: 08/31/09
1 lifetime posts
I bought this new house which has Lennox Furnace Model G20.

My problem is this unit always blow. When thermostat reaches the desired point, the heating/cooling stops but fan continues to run.

Did some research and learnt that this unit can support a continuous fan feature in which a switch is added to the system to run a fan at low speeds continuously.

My unit did not have this switch, instead the CF (continuous fan) pin of the controller circuit is directly connected to third speed tab of the fan, while red pin is attached to the fourth one.

I did disconnect the CF cable to try but fan stopped working while the system ignites and fires up. I stopped immediately.

Is there a way to use the system with activating the fan when the heating or cooling is on?

Thanks in advance

Handyman

09:09AM | 09/14/09
Member Since: 11/18/98
187 lifetime posts
don't play with it.

Call the contractor.

this thing is under warranty. And that you don't want to mess with.

BV002933

12:19AM | 01/04/14
The correct solution is to remove the wire from the 'Continuous Fan' terminal pin (marked CF), and place that wire on one of the Dummy terminal pins (marked D). There is a D terminal pin on either side of the CF pin, you can place the wire that was previously on the CF pin on either one of the D pins, it does not matter which one.

What does matter is that you place the wire you remove from the CF pin on one of the D pins. If you just leave the wire that was on the CF pin dangling (not connected to anything), then you will encounter exactly the problem you described, which is that the fan will not operate when it should operate.

For further information, do a Google search for the PDF document "Lennox G20 Installation Instructions", and once you have that document, look at the illustration of the BCC2 Control Board (figure 13). There you can see the Dummy terminal pins on either side of the CF terminal pin.


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