# Bryant 355MAV furnace and A/C blower not starting



## rajar2 (Jun 17, 2008)

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 it’s speed range by 10 percent.. It’s 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?


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## HvacWiz (Nov 24, 2006)

*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.*


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## rajar2 (Jun 17, 2008)

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


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## cwynarj (Nov 24, 2008)

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.

Thanks


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## HvacWiz (Nov 24, 2006)

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


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## rajar2 (Jun 17, 2008)

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 [email protected]


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## marty0500 (Jan 22, 2009)

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...


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## rajar2 (Jun 17, 2008)

*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

http://www.rtie.com/ntc/sgspec.htm

Hope this helps you out,

Alex


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## jiffyxpop (Jul 21, 2009)

*Bryant 355 mav*

Hi,
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.


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## Plumber101 (Feb 25, 2009)

But the real question is why did it fail?

Is this system about 2 yrs old?


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## jiffyxpop (Jul 21, 2009)

*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.


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## toddshelton (Oct 12, 2009)

*Bryant 355MAV blower failure code 44 SG348 thermistor*

Hello, 

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 (http://en.wikipedia.org/wiki/Thermistor) 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 (www.mouser.com) 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 http://forum.doityourself.com/air-conditioning/270140-ge-ecm-programmable-motor.html#post1606065. 

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.


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## Wildbilldawg (Oct 22, 2009)

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.


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## toddshelton (Oct 12, 2009)

*Thumping blower is probably not a dead thermistor...*

...sorry! 

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!


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## Wildbilldawg (Oct 22, 2009)

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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## Jager97 (Dec 13, 2009)

I had the same problem this morning at 05:30. We woke up to a 60 degree house and no blower motor. I did a quick search and found this thread. The issue was the condensation pan was not draining properly. I emptied the pan and unclogged the line. Blowers on, and we're on out way back to a warm house.


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## bleeda (Jan 5, 2010)

rajar2 said:


> 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 it’s speed range by 10 percent.. It’s got 25 steps.?" Can anybody email me these procedures?
> ...


Don’t know why no one noticed this but the code would be 14 NOT 41
The yellow light is the first digit and the green light is the second digit.


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## toddshelton (Oct 12, 2009)

*Check the motor thermistor*

Take a look at this thread: 

http://www.diychatroom.com/f17/bryant-355mav-furnace-c-blower-not-starting-22408/

It sounds like your motor thermistor has gone away. 

Good luck!


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## hartzog86 (May 31, 2010)

Its been a long time since I played with any circuit design but after looking at this thermister issue it appears Bryant/carrier is using this thermister to slowly ramp up the fan motor over a few seconds to prevent sudden onslot of noise, I know thermistors are also used to manage startup surge for componant protecting but that doesnt seeem to be the case here, my question is can I bypass/jump this SG348 thermistor for a couple of days till the new one comes in?


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## toddshelton (Oct 12, 2009)

Hi Hartzog86, 

I believe that the thermistor manages the inrush current to the motor. As it heats up from motor current passing through it, its resistance drops to almost zero. The motor is a very expensive component (~$700). Unless you are willing to take the chance that you could wreck the motor I would get out the blankets until the new part comes in. 

If you're doing this today you should have the part by Wednesday latest, and it might be available locally tomorrow. 

Good luck!


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## hartzog86 (May 31, 2010)

*Hurry and waitting*

Thanks Todd for your reply, thats what I am doing, I ordered a couple and even paid for next day shipping ($42 shipping on a $4 part) just dont know if I can stand the wife's nagging about not having AC till it gets repaired and was hoping a jumped then continuously run fan would be reasonably safe, I think it would be but was wanting someone with actual vs thearetical experiance to weigh in. Then if it blows up I can tell her it was not my idea  

Zog


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## toddshelton (Oct 12, 2009)

*Hurry and waiting*

Good luck, Zog--didn't realize you need A/C, where we live (NW) we don't. I think I paid something similar to overnight the part, but was glad to to get it at all. I ordered a spare, too--from reading the posts I suspect that the part lives 5-7 years, then dies. I ordered an uprated part (30a instead of 20a) to maybe make this a one-time repair. 

Your wife can blame me--mine does all the time. 

Stay cool, 
Todd


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## hartzog86 (May 31, 2010)

Fan-current limiter-SG-349 update

Found one at Digi-Key corp www.digikey.com (1 ohm 30amp) part #570-101059-ND Current Limiter inrush (Thermister) for $2.64 each (ordered a couple) overnite $21 shipping, $26.28 total. 1hr to remove and replace fan, 15 minutes to R&R thermister. Worked perfectly first time.

Estimated repair from two local companies were within $15 of each other- $865

saved $839 Not to mention the brownie points earned from the ol' lady

DIY to the rescue again.....


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## hartzog86 (May 31, 2010)

*1hp controller board with thermistor*

Thermistor is black disc (standing on edge) in center of photo


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## yuri (Nov 29, 2008)

There are 3 LARGE capacitors in those motors and GE recommends you wait 1/2 hr B4 doing any work on that module so they self discharge. These are BIG ones and can seriously hurt you.:2guns:


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## Mr.Conley (Aug 20, 2010)

*Bryant Plus 90i blower problem stumps the service tech!*

I got a Bryant Plus 90i AC/furnace and our AC went down due to the blower not kicking on 2 weeks ago yesterday and the gas company service man who has been on the job for about 20 years is stumped and is working as I post this. The code said the blower motor was the problem so he replaced the motor, nothing. He then replaced the control head on the motor, nothing. He then replaced the control module that goes to the motor twice just in case and nothing. He replaced the wiring harness from the control circuit board to the motor and still nothing. Luckily this is a small town and he is trying to find out what the problem is and said he is going to treat us right on all the time and parts. He will only charge for the part needed but hasn't been able to locate the source. It was put in in 2002 so it's only 8 years old. Heck he went to their office and robbed all the guts out of theirs today just to get it going at least for the weekend, it's supposed to be close to 100! He is at lunch right now but he said the Bryant tech he has been talking to on the phone don't know what else to try. Any info would be greatly appreciated thanks.


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## Basics (Sep 21, 2010)

Hi:
I have a Bryant 90i 350 mav condensing furnace that has a similar problem to the units discussed above. It starts up ok but fails
to go from low heat to hi heat. Components test = ok, pressure switch test = ok. No codes showing possible component failure.
Any ideas to check out? Is it possible to clean out condensate trap? How do you do this?
Any way to determine if gas valve is at fault?


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## MarshSt (Apr 8, 2011)

*Bryant 355MAV .....Trying to restart this thread, previous posters?*

I had the same issue with the blower motor on my Bryant 355MAV and was able to resolve it with the replacement of the thermistor as explained in this thread.
This board was a huge help...Thanks!

I had been noticing an occasional rumble when the furnace fan was innitially starting up and had investigated all the mechanical possibilities with no luck. The burned thermistor helped point in the direction of a potential solution for the rumble. 
When testing the new thermistor I had the cover off the furnace and was watching the blower motor. On one startup I heard the rumble and noticed that the blower was trying to run but was just sort of vibrating in position like it wanted to start spinning but could not begin rotating. The motor was able to start without faulting the control. I was told that is may be failing capacitors in the motor controller circuit. 
Has anyone else noticed this vibration? Is there a solution out there for the start up harmonic?

Thanks
Steve


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## AnnaB111 (Feb 17, 2012)

toddshelton,

Thank you very much for posting your information. It turned a 1,600$ repair into a 160$ repair. When our furnace motor broke and we got price from BELAIR we were devastating (we have 4 children and my husband salary was cut to 50% less), so I did some research if there would a way to save the motor and replace only the broken resistor. Nobody from my family believed that easy and cheap solution could work. Description in your post was very convincing for me , I did everything what you suggested and VICTORY , our Furnace works again(good because outside is cold !).Great Job ! Thanks a lot ! Anna


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## No Cones (Jun 19, 2012)

*Thank You!*

Armed with a SL22 and a sodering iron I have beet back the Money Demons!
Thank you all who have tirelessly given and given information, great photos, and even Videos to help people.

My Carrier unit is blowing ounce again!


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## Ranchand (Aug 7, 2012)

*Blower issues*

I also have an 11 year old 355MAV with blower issues.
After the blower stopped working it flashed both 44 and 41 codes.
Tech replaced the motor module and the unit ramped up and started working but only at low speed, still flashing 44 code.
Tech says the hi speed motor winding is bad and that we need to replace the entire motor $1600
HELP!?!?
Thanks in adanvce


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## 1HandyMatt (Feb 1, 2014)

*How I fixed my problem*



rajar2 said:


> 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 it’s speed range by 10 percent.. It’s got 25 steps.?" Can anybody email me these procedures?
> ...


:thumbup:

I had the same problem and was determined to fix it myslf after the $1300 estimate I got to replace my blower motor. It in fact was not the actual motor, but the thermistor inside the black hub cap attached to the motor. I ordered the thermistor for $5.15 from Digi-Key, part #495-2123-ND, it is a little larger than the original, but same specs as the old one. It took me a couple of hours for dis-assembly and re-assembly, but well worth the $1100+ in savings!!! Thanks for all the help from the forum!!!!!!!!!


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## ff_mac (Sep 13, 2015)

*Another success story*

Thanks to all for an excellent thread. I too have a Bryant 355MAV that quit working after 16 years with error codes 44/41. I went through the Troubleshooting Guide and got to the conclusion to Replace Control Board. After discovering this thread I removed the blower assembly, removed the controller board, and inspected the Thermister. It was by no means fried, but did have a small burn mark along one lead, like so.








I ordered the #570-1059-ND Thermister from Digikey.com (and 3 spares) for a total of $16, put it in, and works like a charm.

*Notes
*

A T15 security bit is needed to remove the blower motor controller boards from the hub. I bought a set of these from HarborFreight years ago and have only needed to use them twice before. But they are sure nice to have when you need them.
I wasted 4+ hours attempting to verify that the blower was not functioning, and naively thought I could just hot wire it. But there's already 120V to the motor from B1,B2 on the Furnace Control Board, so spin-up of the motor is controlled by the 5 control lines going from the PLA to the motor.
At the back of the Troubleshooting Guide is APPENDIX D—Quick Motor Test Procedure, and I tried following that. Its a PITA because the controller won't work if any of the connectors are unplugged, so one has to bridge the connector in place to get a voltage reading. Got a No to both 39 and 40, which then goes to 22-_Replace furnace control board. _So after 4+ hours I decided to see if the Thermister did the trick, which it did.


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## zappa (Nov 25, 2011)

Good work and thanks for the input.


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## kt22 (Oct 7, 2015)

Another Bryant 355MAV owner with a blown blower... Great posts in this and related threads, but nothing looks like a clear answer, so hopefully ya'll are up for some more remote troubleshooting...

Symptoms: No main fan blower.

History: Purchased/installed in 2001. Heat, no AC, but we run in CF mode during summer months, often for 1-2 weeks at a time (low speed). Fan failure noted about 2 weeks ago. We have had several power outages recently, all planned service events by utility.

Self test proceeds thru all steps except last 2 main fan tests. Code 41: Blower outside valid speed range

Likely problems (Based on DIY Chats): lose solder connection on main control board or Blown Thermistor.

Pulled control board. Lots of dust, but it looks pretty new. Small amount of corrosion on pins behind 11 circuit connector (24v, "PL1" on diagram in manual). No sign of component failure or lose solder. Have pics if I can figure out how to post.
Wiring all looked OK, connections solid, no sign of heat or shorting. Board=HK42FZ012

Pulled Fan. Mine is a right-hand horizontal in the basement, so this was not easy. Control board mount has to be removed first, but in the end it was not that hard either. 
Dis-assembled motor control: No obvious signs of overheating on circuit board. 
Thermistor looks great. Tested 1 Ohm resistance... not sure how to test this component, but it looks like it does pass a current, but this was tested in-place, so I'm not sure of there might be a parallel circuit capable of passing current as well.
Bottom "potted" section looks new.
One of the capacitors shows some sign of... something. Could be corrosion/leakage? Not sure how to test the capacitors as they are soldered in place (same issue as Thermistor)
Tested all 3 fan circuits, each showed about 10 ohms resistance. My meter uses 1 AA battery, and I got a small amount of fan movement out of each of the circuits just from the meter current. Pretty cool, and seemed like a good indication motor is sound.

Tomorrow, I may try the "emergency heat mode", but do not have much hope on that one. This mode bypasses the microprocessor and calls for high speed fan immediately, so is a difference sequence than the self-test.

It has been really dry out here in CA, so I thought condensate trap could have dried out, perhaps confusing a sensor, but there are no sensors in the trap. Seems this unit senses issues with condensate drain by readings from pressure sensors connected to tubes connecting various components. These tubes all appear to be undamaged and fully intact. Pretty sure issues here would throw a different code, but I'm ready to test just about anything... 
Thanks in advance for your puzzle solving!


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## kt22 (Oct 7, 2015)

yuri said:


> There are 3 LARGE capacitors in those motors and GE recommends you wait 1/2 hr B4 doing any work on that module so they self discharge. These are BIG ones and can seriously hurt you.:2guns:


Thanks for the reminder... these are not toys!

My unit has only 2, although there appears room for more. Is number of capacitors related to HP rating, or type of capacitor? A number of references recommend ensuring discharge by shorting the circuit (bridging capacitor terminals with a metal tool). Think this may be a good way to confirm they have completely self-discharged, but probably not a good way to quickly discharge them.
How do these units discharge? Looks like via small chips (resistors?) incorporated into the back side of the circuit board, or is the discharge function built into these capacitors?


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## kt22 (Oct 7, 2015)

Update: I've posted pictures in my album
http://www.diychatroom.com/members/kt22-340249/albums/byrant-mav355/


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## kt22 (Oct 7, 2015)

yuri said:


> There are 3 LARGE capacitors in those motors and GE recommends you wait 1/2 hr B4 doing any work on that module so they self discharge. These are BIG ones and can seriously hurt you.:2guns:


Any recommendations on how to test/troubleshoot capacitors? I'm having issues with blower fan, and the only component with any odd look is capacitors, although the **** could easily be something else dripped down (my right-hand installation results in upside down fan motor unit). Have a look at my album for pic of capacitors.


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## zappa (Nov 25, 2011)

It's unlikely they are bad. The most accurate way is to remove them and test with a capacitance meter. You could try ohming across them while installed but it's difficult to say what the results will be. An experienced person should be able to tell that they are neither shorted or open from changes in the reading but that's about it.


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## kt22 (Oct 7, 2015)

Tried "emergency heat mode", blower still does not work. 
I am leaning towards ordering a replacement motor control module.


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