Furnace Blower Connections Question

Problems related to residential installations.

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Furnace Blower Connections Question

Post by georgofhastings » Tue Jan 03, 2017 7:12 pm

Furnace is Bryant 383KAV042091 AGJA, series G 88BTU/HR

1) There is no cooling equipment, but a blue wire is connected to the "cooling" terminal on the control board. Does it have to be connected? If not, there in no third "park" terminal to attach it to, as the 2 existing ones are already taken.
2) For blower speed control, is the red wire DEFINITELY for the lowest speed? That's what it is on, and the register output is too fierce and barely warm. The other leads are yellow and black. So I figure, that the solution is slowing the blower, but how?
Is the following info relevant to this situation?
Check the furnace rating label - it will have a rated temperature rise for the furnace. Measure the return air temperature and then measure the supply air temperature 12" after the furnace (or after the A/C coil if you have air conditioning) with the furnace running in heat. Subtract the return air temperature from the supply air temperature. If the temperature difference is lower than the rated temperature rise then you have a problem with your limit. If it is higher than the rated temperature rise you have a problem with airflow.

Thanks in advance for any help.

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- Furnace Blower Connections Question

Post by Freon » Wed Jan 04, 2017 7:19 pm

There should be a furnace schematic diagram, usually on the back of the blower motor compartment door. That diagram will verify that red is the slowest speed. Usually red is the slow speed but you need to verify for your furnace. Forget bout the Cool connection. For your situation Cool is like Park.

The big question is... does your furnace keep you warm? Despite being "barely warm" the cubic feet per minute of air output could be very adequate to keep you warm.

To adequately tell you about temperature rise is another topic. If the temperature rise is too great, your BURNER will stop while the blower continues to circulate air until the combustion chamber temperature has cooled to where the burner will relight.

Air flow velocity from a vent is about the size of the blower and the duct work that handles the blower's air flow. More details are necessary to know if you have a problem.

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