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rajar2 06-17-2008 02:45 PM

Bryant 355MAV furnace and A/C blower not starting
Similar problem to another Bryant 355MAV owner.
I hope someone can send me the Bryant check out procedures for a troubleshooting a blower motor that does not start.

"Code 41 is the blower motor failed a test and is outside itís speed range by 10 percent.. Itís got 25 steps.?" Can anybody email me these procedures?
Both my furnace and A/C begin to go through their initial start-up cycles and completes everything OK, gas comes on and lights fine up to when the main blower motor should come on, but it does not start to turn at all - never. At this point the furnace shuts down. Similar results when I start the A/C.
I have the Installation manual and have checked the error message from performing the Component test. Inducer motor starts on Low speed, then Hi-speed, then hot surface ignitor lights up the gas and is on for 20 seconds, then it dies. The blower does not start its low, then high speed cycles. The Fault code is #41 - I get 4 flashes on Green LED followed by 1 on Yellow LED. This sequence keeps repeating. FU1 fuse on the panel is OK and am still looking for FU2. Any ideas?

HvacWiz 06-17-2008 04:47 PM

Code 41= blower out of valid speed range. you will more than likely need a new motor module. they are not cheap 300$ to 400$. If you call a carrier or bryant tech out they should have a test module they carry on their truck that lets you know if its the furnace circuit board or motor module.

rajar2 06-17-2008 07:08 PM

Thanks much. That was a really fast response. I will now check a Bryant dealer for the costs. Appreciate your help.

cwynarj 11-24-2008 11:01 AM

I don't know if you resolved your problem or not but I recently had problems w/my furnace. Similar trouble codes to yours. 1st tech misdiagnosed as secondary HX failure. Bottom line was that the condensate trap was clogged and either needed cleaning or replacement. Good Luck. Let me know what your resolution was.


HvacWiz 11-24-2008 12:20 PM

Wow, thats a expensive mistake made on that guys part.

rajar2 11-24-2008 03:28 PM

I resolved my problem. It was several months ago so my memory may not be 100%. I removed the blower motor assembly and dissassembled the motor controller from inside one end of the blower assembly. The circuit board was found to have one component that was obviously fried. It was a resistor in the form of a ceramic flat button about 3/4" in diameter with 2 legs that were soldered into the circuit board. I located another resistor and resoldered it in and BINGO - all works fine now. I was quoted over $600 for a new Blower motor and Over $300 to $400 for a new power supply board (for the main board that has the trouble code flashing lights, not for the blower motor). It was a problem finding the resistor (I believe that was the correct electronic term) but all's well that ends well. If you are prepared to dig in and investigate you can sometimes save big time. Hope this helps someone else. All the best Alex

marty0500 01-22-2009 11:41 AM

Here's the part rmod44ae120
And I also had the small "resistor" burn out.
On the new one I made sure that the resistor was not leaning against the coil. (which it was in the old one as well as the new one)
I'd love to find this resistor and solder it back in for the next time...

rajar2 01-22-2009 12:34 PM

Surge Guard / Protector part number for Bryant 355 Blower motor control circuit board
The resistor or Surge Guard Protector is SG-348 (no longer available or SG-301 from RTI Electronics.) SG-301 is 1 Ohm at 20 Amps or SG-328 1 Ohm at 30 Amps is OK

Hope this helps you out,


jiffyxpop 07-21-2009 06:22 PM

Bryant 355 mav
I have a Bryant HVAC Model Unit 355 MAV 90i that was installed new in 2000 in my house. The air conditioning stopped working this week so I called a repairman who said the indoor fan motor , a variable-speed blower motor, is dead/faulty and needs to be replaced/installed for $1,570.00.

Is this a reasonable quote? What can I do to fix this on my own?

Any advice would be appreciated.

Plumber101 07-21-2009 07:32 PM

But the real question is why did it fail?

Is this system about 2 yrs old?

jiffyxpop 07-21-2009 10:45 PM

355 mav failure
The repairman didn't say, he just said it was dead. The furnace was installed new 9 years ago. I got a second quote for $1340, I heard the part itself was $1155 since it is an energy saving furnace with a variable speed blower. So much for savings.

toddshelton 10-11-2009 10:09 PM

Bryant 355MAV blower failure code 44 SG348 thermistor

First, thanks to rajar2 for helping me save $1,600! My 355MAV blower failed with a code 44. I found this thread and was cautiously optimistic. I still called the guys who put the furnace in. Their man came out, looked at the codes, check voltage to the blower, and inside three minutes pronounced the motor dead--$1500 to replace plus about $150 for the labor to put it in. Furnace is eight years old, parts warranty lasts for five.

So today I pulled it apart, which took about 45 minutes. Sure enough, in the control head was a burned SG348. I did some research on thermistors. Here's what I found:

Thermistors change resistance when their temprature changes and come in two types: NTC and PTC--Negative and Positive Temperature Correlation ( respectively. Starting from their resistance rating NTC devices' resistance goes down as the device warms up, PTC devices do the opposite.

NTC thermistors are widely used in power supplies as "inrush current limiters". When the power is first turned on and the thermistor is cool it presents its rated resistance, moderating voltage wavefronts, to protect devices behind it. As it warms to operating temperature its resistance goes to nearly zero. It's still in the main power circuit, still has some resistance and therefore generates heat. We ran our blower continuously all summer which is why I think the part failed.

RTI used to make the SG348 and they make an SG100 and SG301 that have the same specifications (slightly different package, either should work). But hard to find.

I went to Mouser Electronics ( and ordered a 1 ohm 20 amp device (871-B57464S109M) and a 1 ohm 30 amp (785-ICL321R030-01) device. Less than $10 for both, shipping $20, total spend $30. The furnace tech charged me $90 to do the diagnostic.

Internet research to find a solution was about 1.5 hours, removing the blower about an hour, removing the part about .5 hours, researching thermistors to make sure I had a good cross-reference took about 2 hours, an hour to write this up and post it. I expect to spend two hours putting the furnace back together.

I figure I made $200/hour. Very good money, especially in today's modern economy. Knowledge isn't just power, it's money!

There's more detailed information on this motor and its problems at

Thanks again so much rajar2--you may not be the only one who figured it out, but you were the one to let the rest of us know.

Wildbilldawg 10-21-2009 07:19 PM

I have a Bryant Model Unit 355 MAV 90i (installed 2000) when the furnace goes into high speed there is a loud thumping kinda sound that is coming from the blower and it also creates a vibration, would this be the same problem as in the previos posts. There is nothing traped inside or anything like that would make the noise. I am sure that the noise/vibration is coming from the blower area.

toddshelton 10-21-2009 07:55 PM

Thumping blower is probably not a dead thermistor...

Take the fan out and see of something is in it or if a vane is broken. Check also the rubber suspension mnounts to see if they are shot.

Good luck!

Wildbilldawg 10-22-2009 08:52 PM

Checked everything and the rubber mounts look ok and there are no broken vanes. Does anyone think that the motor could have issues? Sorry for all the questions but before I spend all the money I saved with this unit I want to narrow down the possible problem. Is there any way to make the furnace run at low speed only?

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