Blower motor on HVAC went south

[sammyg2]

About and hour ago the house started to smell like smoke. A few panic-filled moments and I traced it down to the blower motor on the central air/heater.
I took the motor all apart and cleaned it up (probably the first time, it was really dirty).

Everything looked OK so I reassembled it after cleaning a ton of crud off of the fan.
Put it back in, wired it up and turned it on. Success! I thought.
After a couple of minutes it got really hot so I pulled the plug, prolly going to ground in the field windings or something. I'm no electrician and I know just enough about electric motors to be good and dangerous.

Holiday weekend, gonna be hot, motor may be original to the house (40 years old) as near as I can tell, I'm thinking this is going to be expensive.
Hopefully I can find a replacement that will fit without all kinds of modifications but that's doubtful.
it's always something.
Anyone in North OC with a good HCAC guy that can be trusted? I know there must be one out there somewhere.

[Danny_Ocean]

Grainger or McMaster sell motors. You'll have to find some sort of ID plate on the motor and have the dimensions handy. Does not appear they are open on the weekends, though...

Branch: 442
310 E. Ball Rd.
Anaheim, CA 92805-6312
Phone: (714) 776-8514
Fax: (714) 758-8912

Branch Hours:
7:00 AM - 5:00 PM (Monday - Friday)

Branch: 303
12871 Western Ave., Suite A
Garden Grove, CA 92841-4032
Phone: (866) 613-7214
Fax: (714) 758-8912

Branch Hours:
7:00 AM - 5:00 PM (Monday - Friday)

Branch: 304
16942 Gothard St. #E
Huntington Beach, CA 92647-5456
Phone: (866) 613-7214
Fax: (714) 758-8912

Branch Hours:
7:00 AM - 5:00 PM (Monday - Friday)

[sammyg2]

Does Grainger sell to John Q. Public or just businesses?

[Danny_Ocean]

Originally Posted by sammyg2

Does Grainger sell to John Q. Public or just businesses?

You can set up an account. They're not really retail, but if you set up an account on-line, you can order and go to the store to pick-up.

If you want to get back on-line asap, call an AC guy. If you want to DIY and save some $$$ go the Grainger route.

[turbo6bar]

Originally Posted by sammyg2

Holiday weekend, gonna be hot, motor may be original to the house (40 years old) as near as I can tell, I'm thinking this is going to be expensive.
Hopefully I can find a replacement that will fit without all kinds of modifications but that's doubtful.
it's always something.
Anyone in North OC with a good HCAC guy that can be trusted? I know there must be one out there somewhere.

Actually, this isn't a bad job. This is a common failure mode. If you can find a HVAC supply that's open on the weekend, you can buy a motor. It it isn't a rare jewel, you could be in and out for well under $100. When you buy the motor, get a new start capacitor.

You'll want to note the rotation of the existing motor. A new motor will likely be able to rotate CW or counter CW, and you'll need to connect the right jumper wires to get proper rotation. Additionally, I'd take a picture of the existing wiring connections.

Take the old motor with you. You might even want to leave the motor's frame (base that fastens the motor to the blower housing) attached.

Grainger is good in a pinch, but you'd save even more money at a locally-owned HVAC supply house.

[sammyg2]

There's something that I don't understand.
When the system was plugged in but turned off, I heard a 60 hz hum coming from the motor.
I reached in (carefully) and gave the squirrel cage fan a little bit of a spin and it started turning on it's own but slowly. That doan seem right. It was getting a little power but not enough to make it spin without a jump start.

it's like it's getting stray current when it's not supposed to as if the starter relay is not opening all the way or something or power is feeding backwards. It was doing this before I messed with it too so I can't blame myself for buggering up the wiring. Maybe it's not the motor? Could the motor be getting hot (I mean really hot, 170 degrees on the shell after 5 minutes run time) because of the power supply to it being messed up?
If it's a problem with the control system I may be in over my head. I'm contemplating if I should just call an HVAC company and bend over and take it like a *****.
I wish I knew as much about sparktricity as I do mechanical.

[TerryH]

Sounds like the starter capacitor is shot... get the new motor. The guy at the Grainger desk can help answer your questions on your motor.

[sammyg2]

Originally Posted by TerryH

Sounds like the starter capacitor is shot... get the new motor.

The capacitor is the thing that looks like a flattened coil, right? Kinda like a drinking flask but smaller?

Oh, another detail. it would hum and then with a little help it would spin but probably only a hundred RPM or so. They when I turned on the AC it took off right away and went to full rpm and sounded good, but got hot.
I'm gonna chase down a new motor and capacitor and see if that solves it, if not I'll call in the experts.
Thanks for the help.

[TerryH]

Some HVAC's have shared capacitors for the compressor and fan. Hard to say what your 40 yr old system has and I am by no means an expert. If you're not sure, might be best to consult the experts or wait and one usually shows up here.

[turbo6bar]

Originally Posted by sammyg2

The capacitor is the thing that looks like a flattened coil, right? Kinda like a drinking flask but smaller?

Oh, another detail. it would hum and then with a little help it would spin but probably only a hundred RPM or so. They when I turned on the AC it took off right away and went to full rpm and sounded good, but got hot.
I'm gonna chase down a new motor and capacitor and see if that solves it, if not I'll call in the experts.
Thanks for the help.

Here's a typical start capacitor:


If you check the motor's amperage, it probably climbs as time goes on.

These motors have finite life, and your description fits what I've seen when one goes bad: they get stinking hot and eventually just shut down.

Make certain to clean the blower wheel really well. Dirty blowers reduce flow.

[turbo6bar]

Originally Posted by TerryH

Some HVAC's have shared capacitors for the compressor and fan. Hard to say what your 40 yr old system has and I am by no means an expert. If you're not sure, might be best to consult the experts or wait and one usually shows up here.

That is true for the outside condensing unit (condenser fan and compressor share a capacitor), but inside, the blower motor has a single start cap.

[TerryH]

See how a little knowledge is dangerous? I knew we were talking inside blower motor and I got side tracked.

[scottmandue]

Twenty years ago I could of helped but that was the last time I touched an HVAC unit.

What everyone has said is right on, motor or cap... motor is suppied by a relay that should be either on or off.

Unfortunatly really bad timing re: AC going out Saturday morning on a hot muggy three day weekend.

They are giving hotel rooms away in Vegas... road trip?

[sammyg2]

Originally Posted by turbo6bar

Here's a typical start capacitor:


If you check the motor's amperage, it probably climbs as time goes on.

These motors have finite life, and your description fits what I've seen when one goes bad: they get stinking hot and eventually just shut down.

Make certain to clean the blower wheel really well. Dirty blowers reduce flow.

Yep, it has one of those capacitors mounted on the outside of the fan nacelle.

Last night I spent about 15 minutes cleaning the fan and 20 minutes cleaning up the mess I made from it. That thing was filthy.
We have a saying at work: "we'll be cleaning fans for a month".
We say that when the ***** is getting ready to hit the fan. I was thinking about that when I first saw how dirty this fan was.

Tomorrow and Monday are supposed to be cool and only get into the middle 70's. I think I'll just spend today in the pool (with beverages of course) and try grainger on Tuesday. I have next week off so that works.

I checked Grainger's website and it looks like the motor will cost around $100.
If I can get this thing up and running for under $200 I'll buy everyone on this board a beer. No wait, on second thought ........

[jhelgesen]

I did this same thing a few years ago. Blower motor died, took it out, cross referenced the motor number on graingers site, ordered a new motor, had it fixed for $75 within 3 days.....

[Hugh R]

Buy everyone who helped on this thread a beer. Good luck.

[scottmandue]

Uh, you do have a filter on that HVAC system right?

[sammyg2]

Originally Posted by scottmandue

Uh, you do have a filter on that HVAC system right?

Yep, 3M filter that i change regularly. I buy 10 at a time and that lasts about a year, maybe a year and a half.

I have no idea how old this system is but I've lived here for 14 years, so it has to be older than that.

[scottmandue]

Originally Posted by sammyg2

Yep, 3M filter that i change regularly. I buy 10 at a time and that lasts about a year, maybe a year and a half.

I have no idea how old this system is but I've lived here for 14 years, so it has to be older than that.

Too bad... back in the day I used to change out those old heaters... I have seen and handled some real antiques. I would check the fans when I pulled the heater and if they were in resonable condition I would pull them and had a pile in the back of the shop.

[TerryH]

My furnace and blower are under my house. They had to either build the house over it or assemble it down there because the crawl-space opening is only ~3 ft square. Pain in the butt to change filters.