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gsb6829 · Mar 9, 2011, 07:16 PM

I have a Ducane DOLA84/95F4-AB Oil Furnace/air handler. The AC system is hooked into the same unit. The furnace fires up and makes heat with no problem. However the fan is not spinning.

First I pulled the fan and bench tested it - ran it on each speed for a while under load and everything seemed fine.

Checked power to the fan and found that it was not receiving any. I then followed the lines back to the circuit board and the lines running to the fan were not receiving power from the circuit board.

After pulling the circuit board I found the K1 Relay to be burnt on the back of the board as well as resistor R5 and R6.

If anyone has any information concerning this problem I would greatly appreciate it.

Thanks!

mygirlsdad77 · Mar 9, 2011, 08:12 PM

Hi gsb. You will need to purchase a new board. Individual parts on the board are not repairable or replaceable. They only sell the board as a complete unit. As long as the motor and capacitor check out, a new board should have you up and running.

gsb6829 · Mar 10, 2011, 05:08 AM

Thanks mygirlsdad77... Like I said I ran the motor on the bench for a while and everything seemed all right to me, but I'm not a pro.

Is there a separate way to check the capacitor to make sure that's OK? Also, do you have any idea what could have made the board blow? Is this a fairly common problem? I just don't want to replace it and run into the same issue. Is it possible that too much resistance on the fan caused it. I know I don't have the best air return system set up right now because of some temporary construction. Thanks again!

mygirlsdad77 · Mar 10, 2011, 04:31 PM

High amp draw on the motor is a possability, but many times the board just fails for no real reason. If your concerned, take the motor and capacitor to an electrical shop and have them test it for you. However, bench testing will only tell you if the motor is working correctly on the bench. If the air flow is restricted in the unit or duct work, it will cause the motor to draw high amps. I would suggest checking amp draw with the motor in the furnace, while somehow sealing the blower door so its running just like it normally would. If your motor starts up fine and amp draws are within range listed on the motor, then your cap is probably fine. But, capacitors are cheap and easy to replace, so it couldn't hurt to just get a new (same rated) one. If all checks out there, check 120 voltage coming into the board, and if that is within range, there should really be no worrys about ruining the new board, or course its hard to say without actually being there to put my hands on the thing. Look for any signs of moisture that may have gotten on the board, as that would also cause your problem. Hope the new board last for years to come. Good luck, take care.

PS. Fan motors have an internal overload that will trip if the motor gets to hot from high amps, once the motor cools off, the overload will reset itself. Normally this will happen over and over again before doing any damage to the control board.