Looking for Carrier Variable Speed Inducer Motor Assembly


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Old 12-12-09, 10:44 AM
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Looking for Carrier Variable Speed Inducer Motor Assembly

Looking for a carrier bryant 90i ecm variable speed inducer motor assembly

Used is fine as long as that it is in good working condition

(324906-762,320727-755) carrier part#s
used on carrier 58mvp & bryant 355mav variable speed 90% furnaces
thanks Mark
 
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Old 12-12-09, 11:47 AM
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I'll bet a new one is expensive!

My bias is towards the single stage 90% units. My theory is that manufacturers may have figured out how to make those work after a few decades of practice.

The two stage furnaces are sort of version 2.0 and the continuously variable furnaces are version 1.0.

How old is your furnace? And I'm presuming that you are confident that the inducer motor is bad?



Seattle Pioneer
 
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Old 12-13-09, 09:42 AM
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Seattle is correct. A New one is $500+ . A hvac tech came & looked at the furnace. Error code from the inducer pressure sensors. Changed the pressure sensors, same problem. When he forced the sensors to give a good signal, there was flame rollout from the burner tubes. He said it was either a bad inducer motor assembly or bad heat exchanger.

Furnace is 9 years old.

thanks
Mark
 
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Old 12-13-09, 10:31 AM
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Originally Posted by MarknRochester
A hvac tech came & looked at the furnace. Error code from the inducer pressure sensors. Changed the pressure sensors, same problem.
thanks
Mark


Umm. Yet another repairman who doesn't use a manometer to determine what is wrong when a pressure switch opens.

Does no one get any training on this skill?
 
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Old 12-13-09, 10:35 AM
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A restriction in the vent piping can also cause a pressure switch lockout and is much cheaper to repair.


Check for leaves or restrictions outside at your pvc vent intake and exhaust.

You can shut off the gas to the furnace and remove the vent pipe to see if the pressure switch makes with no vent pipe.
 
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Old 12-13-09, 10:49 AM
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I appreciate the ideas.

Restriction in the inlet & exhaust pipes were checked for. A Manometer was used as well. He said somethng like readings are low positive numbers when they should be larger & negative.

thanks again
 
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Old 12-14-09, 06:10 PM
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Originally Posted by SeattlePioneer
Umm. Yet another repairman who doesn't use a manometer to determine what is wrong when a pressure switch opens.

Does no one get any training on this skill?
But being an HVAC guy, he probably determined it be quicker to just temporarily slap on one(maybe not even mount it) from his truck, and also jumper the wires to automatically conclude that there is an internal furnace or vent problem, rather than a switch problem.

Our HVAC guy operates the same way. He is not like me. In fact he sort of reprimanded me the other day for cheapening out and finding a capacitor to make the inducer work. He said he just would have stuck in a new inducer and been done with it. He said all I did was buy a little time, and within a year probably the thing would poop out. I don't think he cares about trying to problem solve, for problem solving sake, to see if he can mentally defeat.....figure out the problem...., the way I do. He simply thinks about time and money and goes about how he goes about it the fastest way to arrive at the same conclusion. And he has years of experience and is fast. He is more into new installations from scratch, and fabricating the duct and all that. He doesn't have time to mess around trying to figure out goofy maladies. He'd throw in all new parts at the furnace till he hit the right part, I think. But he is a good guy. He would only charge for the part that fixed it, then remove the other ones to be used as test pieces on some other furnace malfunction.
 
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Old 12-14-09, 08:58 PM
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Seems like a low positive number would indicate a restriction after the inducer. I hope he checked that well. It would be terrible to spend 7 or 8 hundred dollars if a mud divers nest is restricting the vent outlet.
 
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Old 12-14-09, 09:08 PM
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Originally Posted by ecman51`
He is more into new installations from scratch, and fabricating the duct and all that. He doesn't have time to mess around trying to figure out goofy maladies. He'd throw in all new parts at the furnace till he hit the right part, I think. But he is a good guy. He would only charge for the part that fixed it, then remove the other ones to be used as test pieces on some other furnace malfunction.

He's an installer trapped in the role of repairman. You also find repairman trapped being installers. Neither one is good.

Well, the method you describe can work, but it's not a very elegant diagnostic method, and it's prone to repeat service calls.

And not my style. With pressure switch problems, using a manometer allows you to identify whether the pressure switch is the problem right away, and then it allows you to know for sure when you've identified and cleared the problem. It's fast, accurate and reliable.



Oh, well.
 
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Old 12-14-09, 09:31 PM
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Here is the instruction manual for the furnace.

http://www.xpedio.carrier.com/idc/gr.../58mvp-8sm.pdf


It looks like the inducer motor has a low speed and a high speed, and that the proper speed is actually calculated by the microprocessor based on a test described on Page 2, step 2.

This is complicated enough that our pressure switch changing repairman probably doesn't really know or understand what is happening, and I have doubts about his diagnosis of replacing the inducer motor.

Diagnostic codes for the inducer motor and pressure switch are 31, 32, 41 and 42. Check and see which if any of these codes are flashing. (Page 8 of the manual)
 
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Old 12-14-09, 09:35 PM
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The instruction manual goes into commendable detail on the problems associated with various diagnostic codes.


Did you have a copy of the instruction manual for the repairman to review when he came out to work on the furnace?

If he didn't have a manual, I'd say his diagnosis is suspect. This furnace is too complicated for the ordinary diagnostic methods suitable for simpler furnaces.

I'd print out a copy of the manual and leave it on the furnace where it will be readily available for anyone working on it.
 
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Old 12-14-09, 09:48 PM
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I notice that on Page 4, Step 8 there is a test of most major components, including the high and low speeds of the inducer motor. It's probably worth reading that section carefully and performing that test.
 
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Old 12-15-09, 03:54 PM
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Originally Posted by Houston204
Seems like a low positive number would indicate a restriction after the inducer. I hope he checked that well. It would be terrible to spend 7 or 8 hundred dollars if a mud divers nest is restricting the vent outlet.
I'm sure this kind of stuff happens all the time. And not just in the HVAC world - but the car world, the doctor world, etc. In fact, my next door neighbors car went whoomp, whoomp, whoomp on only 1 cylinder and was diagnosed by the shop who towed him as a cracked distributor cap with bad plugs. And $250 later his car breaks down on him the day he got it back from the mechanics, at 11 at night, 40 miles from home. And it was very cold out. I bet a dictionary would not have contained the language spoken.
 
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Old 12-16-09, 07:41 AM
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thanks ecm & seattle

I remember that the error code was 32 & I'll print out the servicing manual & dive into it this weekend

Thanks again for your help
Mark
 
 

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