It's not the motor, and it's not the capacitor...

[overknight]

The system in question is a 15 year-old Carrier, model 394GADO48125.

2.5 years ago, the blower motor began acting up (humming and not starting) and it and the run capacitor were replaced. At that time, I could spin the blower cage by hand (I know, not smart) and I could often get it to start. About four months ago, the humming and not starting started again, again with occasional success with hand-starting. The run capacitor was the problem this time, and after replacement, everything was fine. About two weeks ago, the same problems reoccurred, getting worse to the point I couldn't start the blower by hand-starting. I replaced the run capacitor, this time with no improvement. I noticed that the solenoids in the electronic motor/gas controller (sorry, I'm not sure what it's called) had been arcing quite a bit, so I took them apart and cleaned up the contacts, which were pretty burned. While I had everything out, I checked the motor by putting 120 volts into each of the three motor leads; this resulted in apparent proper motor performance (quiet and smooth, with three different speeds). Reassembly of everything yielded no improvement, though.

At this point, it seems pretty clear to me that this controller is defective. I've been gathering quotes from HVAC contractors to replace the entire system, but it will likely be a few months before everything is completed. I know prices can't be dicussed here, but are used controller units commonly available? I don't even know where to begin to ask where I could find one. Most of the HVAC contractors in this area don't sell parts (and it seems like they're ALL currently on vacation). What are my options?

Thanks.

[smokin68]

Option 1....a SERVICE CALL


Option 2.... sweat







there's no such thing as a temporary repair.

[overknight]

Thanks - as I said, many of the HVAC contractors, particularly the one I'm leaning towards to replace the entire system, are on vacation. It seemed like 50% of the ones I called left a message saying they'll be back after Labor Day.

[4l530]

If it is the control board? you are referring to.
They're easy to get ahold of. To a Carrier/Bryant dealer at least.
HVAC contractors going on vacation in August. Whats up with that? They close down the whole shop??
You do need a good service tech to properly diagnose the exact problem.
But until your "contractor" is back from vacation there is a way to make it work...probably ;)
Good luck and be careful.
BTW in the absence of a HVAC service guy a good electrician might know something about it.

[RoBoTeq]

I think you are assuming something that is not your problem. You are admitting to being comfortable with putting yourself into dangerous situations, so it may not be advisable for us to give you any more ammo for you to shoot yourself in the foot with.

May I suggest having a good HVAC pro do a static pressure evaluation on your system? I doubt if what you "think" is happening is actual what "is" happening. That board does nothing but switch components on and off. Something else is going on.

When was the last time you looked at the condition of the evaporator coil?

[thoglow]

CALL FOR SERVICE.

[jim baughman]

I would not suggest thinking about used parts, especially electric components. New parts are not that expensive.

But if you are having so much trouble with the capacitors and blower motors going bad, I would think that there is a problem somewhere else causing this problem. There are several things that control that blower motor ....contactor, control board, thermostat, and time delay relay. You really need someone to physically diagnose this problem for you. It is hard to repair electronic problems without looking at the unit. There are just too many things that need to be checked and some using a voltage test meter....suggest you really should have someone qualified to check this problem. As mentioned above, an electrician could bail you out if no one else is available.

[overknight]

Thanks, everyone, for your replies.

41503, yes it is the control board I'm referring to, Thank you for correcting my terminology. After getting suboptimal and expensive service from others, I'd like to stick with the guy I found. It seems to be a smaller outfit which may be why they completely shut down for vacation, but I trust him and would much rather give him my buisiness.

RoBoTeq, I appreciate your concern. I don't understand how a problem with an evaporator coil will cause the blower motor to not start; please explain. And yes, the filter is cleaned regularly.

Thoglow, as above; my preferred contrator isn't available. I do have above average mechanical abilities and know how to use a VOM, so if there was something I could do to get this thing running without throwing a lot of money into it (since it WILL be replaced soon), that's what I like to know.

Thanks for your constructive advice, Jim. The motor seems to be fine, at least without a load. Tonight I'll check the voltages coming out of the control board; I should have done that when everything was apart. I think the motor may sit there and hum if it's not getting enough voltage.

Thanks again, everyone.

[overknight]

Maybe even the pro's will learn something from this, not that they'd admit it... ;-)

I checked the voltages coming out of the controller: 120 volts on both the high and low outputs, so that kinda rules out the controller as a source of the problem. Just to check, I connect 120 to the motor again, and this time apply a little load by grabbing the shaft. Again, it starts right up on all three speeds, and seems to have plenty of power. I hook everything back up, reinstall it into the furnace, turn on the power, and the motor just hums. Now I really feel stumped: 120 volts is coming out of the controller, and when 120 is put into the motor on the bench, it starts right up. Keep in mind, this motor is only 2.5 years old. I keep the heat set to 68 and the AC to 78, so it's not like this thing has had a hard life. However, something changes when the motor is mounted back into the furnace.

After more probing around, I found that there was a fair amount of play in the motor shaft. When I was testing the motor on the bench, the shaft was in a vertical position, and it ran fine. When mounted horizontally with the blower cage attached, there was enough weight on the shaft, and enough play in the bearings, that for some reason it wouldn't run. I say for some reason because the motor and blower cage turned smoothly, with no internal grinding or rubbing noted. Obviously, certain clearances need to be maintained between the armature and the field, and the worn bearing weren't doing it.

I wouldn't have thought that the bearings would wear out in 2.5 years, but that's what happened. I was able to purchase a new motor, and now everything's cool, literally.

The motor that died was a Dayton; the new one is an A.O.Smith. The Dayton actually looks more substantial, but obviously looks don't mean much. I'm still going to replace the entire system within the next few months; with this new motor, I figure I'll have a great exhaust fan for my workshop.

Thanks again to everyone who tried to help.

[nickellhead]

next time you run into a situation like that just check the amp draw on the motor nad it should tell you

But Im just curios why are you replacing your whole system if its still working


If it aint broke dont fix it!

[overknight]

Nickel, I'm replacing it because 1) it's 15 years old, 2) it's inefficient, and 3) it's a single zone system; I'm going to have a two-zone system installed.

You're right about checking the current draw; I didn't think of that.

[Edited by overknight on 08-25-2006 at 08:35 PM]

[Steve Wiggins]

Originally posted by overknight
And yes, the filter is cleaned regularly.




In case you guys missed it, here is your clue to why the new system is going to have similar or even worse problems.

Some DIYers are hell bent is all I can say!

Hope your "exhaust fan" doesn't burn your shop down :(

[4l530]

Nice catch overknight. This type of thing is what makes troubleshooting via the internet so tough.
Did you find a nice stripe of oil inside the blower housing or all over the bottom of the motor?
BTW, I think what RoBo was referring to the other evening was how having too much static pressure (as from restricted airflow ie plugged evaporator, lousy ductwork) can thrash a blower motor.
So it may not be a bad idea to have your ductwork checked when you get your new system.
Thanks for the report back.

[overknight]

Thanks, 41530. The motor and blower housing are quite clean; no clues there. I think I just had a lemon of a motor. I'm sure the ductwork is suboptimal. There's one return for the second floor and two for the first, with none in the bedrooms. The side of the evaporator I can see, next to the humidifier, looks very clean, and there's good stong airflow through it when I remove the water pad.

Steve, I'm not clear on what you're trying to say.

[RoBoTeq]

Originally posted by 4l530
Nice catch overknight. This type of thing is what makes troubleshooting via the internet so tough.
Did you find a nice stripe of oil inside the blower housing or all over the bottom of the motor?
BTW, I think what RoBo was referring to the other evening was how having too much static pressure (as from restricted airflow ie plugged evaporator, lousy ductwork) can thrash a blower motor.
So it may not be a bad idea to have your ductwork checked when you get your new system.
Thanks for the report back.

Thanks; saved me some typing :D

[RoBoTeq]

Originally posted by overknight
Steve, I'm not clear on what you're trying to say.

Don't worry about it, no one ever is.

[overknight]

Thanks, RoBoTeq. I wasn't planning on loosing sleep over Steve.

I took the Dayton motor apart. It looked like a brand-new motor inside; absolutely no dirt or dust. What I found was: 1) there are bushings, not bearings, which somehow didn't surprise me, and 2) the bushing has a square cut-out on one side, where a felt packing that's saturated with lubricant contacts the motor shaft. The problem is that the amount of bearing surface area on this side is marginal; this side of the bushing should be positioned on top, on the non-weight-bearing side of the motor shaft. There's no apparent markings on the motor that state "THIS SIDE UP WHEN MOUNTED HORIZONTALLY", but there should be. Do these motors usually have an up and down side?

If I can get a replacement bushing, I'll have a spare motor (or think of the exhaust fan I can make with TWO motors, Steve...), because the bearing surface on the motor shaft isn't damaged. I'm not looking forward to taking this thing apart again, but I'm going to pull the new motor out of the furnace to see if it has the same bushing arrangement, and I'll make sure the up-side is up.

Thanks again, everyone.

[Steve Wiggins]

Can you describe your air filter for us please..... You know, the one that you take out and clean..

Can't believe no one caught this...

Why do I always have to be the godfather around here?

[turtle]

Originally posted by overknight
The system in question is a 15 year-old Carrier, model 394GADO48125.

2.5 years ago, the blower motor began acting up (humming and not starting) and it and the run capacitor were replaced. At that time, I could spin the blower cage by hand (I know, not smart) and I could often get it to start. About four months ago, the humming and not starting started again, again with occasional success with hand-starting. The run capacitor was the problem this time, and after replacement, everything was fine. About two weeks ago, the same problems reoccurred, getting worse to the point I couldn't start the blower by hand-starting. I replaced the run capacitor, this time with no improvement. I noticed that the solenoids in the electronic motor/gas controller (sorry, I'm not sure what it's called) had been arcing quite a bit, so I took them apart and cleaned up the contacts, which were pretty burned. While I had everything out, I checked the motor by putting 120 volts into each of the three motor leads; this resulted in apparent proper motor performance (quiet and smooth, with three different speeds). Reassembly of everything yielded no improvement, though.

At this point, it seems pretty clear to me that this controller is defective. I've been gathering quotes from HVAC contractors to replace the entire system, but it will likely be a few months before everything is completed. I know prices can't be dicussed here, but are used controller units commonly available? I don't even know where to begin to ask where I could find one. Most of the HVAC contractors in this area don't sell parts (and it seems like they're ALL currently on vacation). What are my options?

Thanks.


This is turtle.

the Glass relays on the board do spark when you have a overloaded motor.

Here to do.

Replace the whole system.

Replace the motor.

Call On Star by GMC.

TURTLE

[overknight]

Steve, I use a washable filter element. Instead of buying a new filter every month (and filling up landfills with the old ones), I can rinse it out, let it dry and reuse it. None of the HVAC contractors that have inspected my system while they were here to give me quotes had any issue with it. You seem to be the only one here who either hasn't heard of them or disapproves of them.

Any thoughts on if these motors have and up and down side when mounting?

[MikeJ]

Good job O.K. Some techs here have it in their heads that a homeowner can't solve problems with their systems by themselves or clean a filter. Course that is because of the large amount of dirty filters that they see. Been there, done that. As for static pressures and the like, many techs don't have the knowledge or the equipment to properly check it.

You would not want a tech to spend the time that you spent in finding out why a motor failed. We just know they do, and more often than we would like. Mass production and locality of that production are the key. An average tech would have found voltage to the motor and gone into the replacement mode. A good tech, like Robo, would look for the reasons for failure of a part.

As stated, if your new contractor is good, take his advice on altering ductwork if needed. Better comfort will also be a result.

[jim baughman]

Originally posted by MikeJ
As for static pressures and the like, many techs don't have the knowledge or the equipment to properly check it.

You would not want a tech to spend the time that you spent in finding out why a motor failed. An average tech would have found voltage to the motor and gone into the replacement mode. A good tech, like Robo, would look for the reasons for failure of a part.



I have the equipment to check all static pressures, return draws, etc....even digital charging scales for freon. I am prepared and qualified....and I do check the reason for every failure adequately. I never "parts change" to find a problem. Sometimes it is normal wear and age, sometimes you have to look deeper....I hate recalls and have very few that have ever complained or called back for service. But when you do repairs for warranty companies...you are limited to what they want you to do....patch and go in most cases. They only want it running again as cheap as possible.