I have a Bryant 90 Plus (350 MAV) gas furnace that is about 13 years old with an intermittent problem. The inducer motor starts, igniter lights, gas valve opens, and burner lights and runs but occasionally the blower motor will not start. When this occurs the plenum attached to the furnace gets quite warm before the burner shuts down. A burnt smell comes out of the duct work in the house. A code #13 flashes on the control board. Most of the time I can shut off the power switch to the furnace, wait a minute or two, turn the power back on and the blower will run (code #12 flashing - blower on after power up). The blower will run for about a minute than shut down. If there is a demand for heat, the furnace will start up and run normally sometimes for three or four days without a problem. During this time there are no flashing codes on the control board.

The capacitor on the motor tests good. The blower fan turns freely. There does not seem to be play in the motor bearings, although it does seem that the motor at times does not come up to speed immediately like it is laboring slightly. I have run the Component Test and the blower does run fine on both high and low speeds during the test cycle.

About a year and a half ago the circuit board was replaced as was the pressure switch that mounts to the inducer housing.

It seems that either the circuit board or the blower motor could be bad, but because it is an intermittent problem I have not been able to isolate the problem. Because these two parts are the most expensive parts of the furnace and I would rather not replace them if it is not necessary.

I appreciate any advice.

Thank you

You said you tested the starting capacitor, but I would still be very suspicious of it. Capacitors are difficult to test, and unless you swapped in a known good capacitor, I'd bet the cap is the problem.

Best of luck,
Wally H.

If not the cap, the motor may just need replaced or repaired. Windings, bearings, or brushes (if applicable) may be bad.

If the problem is predictable, put an amp meter on the line, this will typically help narrow the problem down.

I replaced the capacitor on the blower motor and the furnace has run for three days without a problem. I hope it continues to run!

Thank you for the help and suggestions.

Excellent! Please rate my answer if you used it.
Wally H.

Hi we have found forums to be very helpful. We repaired our bryant 90 plus 350mav system because of them. It saved us 400.00 dollars. By repairing our control panel two weeks ago. Now the fan motor on the ac compressor is buzzing we shut it down it spins freely and will start up when spinning it. Not sure if there's a motor capacitor or if maybemotor is weak. Not into buying new motor if that's not the problem seeing how the motor runs fine. After getting it spinning. If anyone had this problem would really appreciate the help thank you chevymom.

You really should start a new thread for this, but there is a starting capacitor inside the condenser housing that usually has two capacitors in a single can--one for the compressor motor and one for the fan motor.

WallyH

I have a bryant plus 90 furnace which was installed in 1990. Just had it serviced for winter and I now notice when it starts it sounds like a fluttering sound and takes about 1minute and half before furnace clicks on.

I don't remember it taking this long to start before and was wondering if anything was wrong. During the furnace checkup technican replaced a run capacitor 7.5.

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