Furnace blower motor question...

1eyefishing · Mar 5, 2017

Since I've noticed so many other on point answers to specific problems in this sub forum, I thought this may be my best shot for an answer...
One of my pops furnaces quit warming its share of the house. When I noticed it, I called the HVAC guys and they sent a technician out to look at it.After a few minutes with the furnace I clearly heard the blower motor run fine for a while and figured he jumped it off and bypassed whatever problem had arisen. Then he came out and said the blower motor was shot and there was no reason to put a new blower motor in such an old system and that we ought to buy a new system. Since I heard it running fine, I am of the belief that it is some other problem in the electrical system getting electricity to it.
What gives?
I think I should get a second opinion instead of going with a company that has installed and serviced this unit for the last 12 years.

Thanks in advance to all those in the know who make this sub-forum an excellent resource...

maker4life · Mar 5, 2017

You may have heard the vent fan rather than the blower. Either way you can change the blower much cheaper than a new system. As long as there's not a crack in the heat exchanger I would stick with changing the motor.

1eyefishing · Mar 5, 2017

It is one of those variable speed systems. I could tell by the way it fired up slowly at first and then blew harder that it was the same fan noise I regularly hear. The technician said that the heat exchanger and everything else was fine.

Thanks...

Artfuldodger · Mar 5, 2017

Will the blower run with the thermostat in the "on" position instead of "auto"?
Below is a basic wiring code for the low voltage terminal strip.

"R" is 24v hot.
"Y" is cooling
"W" is heat
"G" is fan
"C" is (would be) common. Or if you think in 120v terms neutral or ground.

You could jumper red to green which simulates a fan "run" call on the terminal strip of the furnace where the thermostat wires attach.
The technician might have did that to run the fan and decided not to go any further.

I'm not too familiar with those variable speed blower motors beyond making sure your "G" fan terminal has 24 volts to call for it to come on.

1eyefishing · Mar 5, 2017

Artful, thanks for your reply, but you're basically speaking a foreign language to me. Ha. I just can't understand why the fan came on momentarily as I am used to hearing and then the technician comes out and says the blower is shot. If he turned it on and it worked fine, I'm guessing that the problem is elsewhere in the switches or something. I've decided to call them a separate service that has done me and my relatives very well to have him give his opinion. I think if everything else but the blower was fine, I'd agree with maker4 for thinking that it is cheaper to replace the blower than the whole unit.
Thank you, also.

JohnK · Mar 5, 2017

You need a second opinion...nobody replaces a 12 yr old unit over a fan motor. Amazon may sell that part for a third of retail.

Artfuldodger · Mar 5, 2017

1eyefishing said:
Artful, thanks for your reply, but you're basically speaking a foreign language to me. Ha. I just can't understand why the fan came on momentarily as I am used to hearing and then the technician comes out and says the blower is shot. If he turned it on and it worked fine, I'm guessing that the problem is elsewhere in the switches or something. I've decided to call them a separate service that has done me and my relatives very well to have him give his opinion. I think if everything else but the blower was fine, I'd agree with maker4 for thinking that it is cheaper to replace the blower than the whole unit.
Thank you, also.

Sounds like a good plan. Keep us posted as to what they find and/or suggest replacing.

1eyefishing · Mar 5, 2017

Artfuldodger said:
Sounds like a good plan. Keep us posted as to what they find and/or suggest replacing.

10-4. btw- no the fan will not blow when it is on on instead of Auto... Definitely going to have somebody else come look see. Thank you again.

hipster dufus · Mar 5, 2017

Capacitor. Spin it and see if it will run

Cmp1 · Mar 6, 2017

hipster dufus said:
Capacitor. Spin it and see if it will run

Or he changed speeds on the blower motor,,,, as long as the heat exchanger isn't cracked, I certainly wouldn't replace the furnace,,,,

Artfuldodger · Mar 6, 2017

I think the OP said it was a variable-speed motor which works a little different than a multi-speed motor. In regards to changing the speed wires.

I was wondering about the capacitor myself, if one could spin the blower by hand and see if it runs.

Cmp1 · Mar 6, 2017

Artfuldodger said:
I think the OP said it was a variable-speed motor which works a little different than a multi-speed motor. In regards to changing the speed wires.

I was wondering about the capacitor myself, if one could spin the blower by hand and see if it runs.

Didn't notice that, if it is variable, could be the controler,,,, and to replace would be very costly,,,,

1eyefishing · Mar 6, 2017

So, the technician that my wife referred me to just came. He said that the motor was bad but it could be the control board that comes with it. Both parts cost about 1600 bucks together and if the problem turned out to be one or the other he could return one part and I may be able to get by with his little as eight or nine hundred bucks on parts. He said that this was a very high-end furnace and would be at least $5,000 to replace.
I was suspicious that the original technicians argument for a new furnace was illogical.
Y'all did nothing but confirm my suspicions...
Thanks all...

Original technicians argument = good way to lose business...

Cmp1 · Mar 6, 2017

1eyefishing said:
So, the technician that my wife referred me to just came. He said that the motor was bad but it could be the control board that comes with it. Both parts cost about 1600 bucks together and if the problem turned out to be one or the other he could return one part and I may be able to get by with his little as eight or nine hundred bucks on parts. He said that this was a very high-end furnace and would be at least $5,000 to replace.
I was suspicious that the original technicians argument for a new furnace was illogical.
Y'all did nothing but confirm my suspicions...
Thanks all...

Original technicians argument = good way to lose business...

Variable speed DC motors and controllers are really expensive,,,,

Artfuldodger · Mar 6, 2017

A co-worker of mine suggested converting it to a regular multi-speed motor.

Cmp1 · Mar 6, 2017

You could, but you wouldn't get a contractor to do it, liability issues,,,,

JohnK · Mar 10, 2017

1eyefishing.....if you have the make, model of that furnace convenient how about posting it? I don't know anything about ac/furnace units but this stuff about variable speed motor control blowers on home units has my curiosity up. I'm just going to try download some drawings so I can check it out. Thanks for any help.

1eyefishing · Mar 10, 2017

JohnK, the unit is a trane xv80, small sticker says model number txc 054S3 HP CO.
It went into service in 2006. I had a technician come out to try to replace the motor and or the control module and or the control board. The module and/or board was bad in addition to the motor and the new parts were going to add up ridiculously close to a new unit that would have a new 10 year warranty. I am having the whole thing replaced.

JohnK · Mar 11, 2017

Thanks, sorry for your loss.

Furnace blower motor question...

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