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zbitner · Jan 19, 2009, 08:40 AM

My model # G9T08012UPB13C furnace inducer motor started making a horrible sound. I turned the unit off. I pulled the motor and opened the wheel housing to find the wheel was still attached to the motors spindle, but the edge of the wheel had been damaged and was scraping the side of the housing, making the noise. Without the obstruction the motor runs fine. Should I just replace the inducer or is there a larger problem that may have caused this. The furnace is 4 to 5 years old. Is this a common problem?

One thought, the intake has had a build up of ice near it, but the filter screen is still intact. It would be rare, but the smallest piece of ice could have been sucked up I suppose. Long shot, but it was pretty cold in Chicago the past few days and a warm up may have freed a few things, but no ice was directly surrounding the intake. OK, any thoughts?

http://www.hamiltonhomeproducts.com/...T-UH-Parts.pdf

dac122 · Jan 19, 2009, 10:31 AM

I was likewise thinking you ingested something that damage the impeller. Could have been ice or the other sworn enemies - kids and pests. How does it sound when running? If its out of balance you will know shortly.

I can't think of any harm it would do to ride it until it dies. If you do then come up with a backup plan such as having a spare on hand or find some place that can get it quickly.

zbitner · Jan 20, 2009, 12:32 PM

Thank you, I just replaced the damaged wheel and the motor is working fine. However, I now get a three blink code warning of the pressure switch is stuck open. Any thoughts. The inducer motor was only running under distress from the broken wheel for a max of 60 seconds. Could that have damaged the pressure switch? Any other ideas on getting the switch working?

dac122 · Jan 20, 2009, 12:39 PM

Originally Posted by zbitner

Thank you, I just replaced the damaged wheel and the motor is working fine. However, I now get a three blink code warning of the pressure switch is stuck open. Any thoughts. The inducer motor was only running under distress from the broken wheel for a max of 60 seconds. Could that have damaged the pressure switch? Any other ideas on getting the switch working?

Start by checking to see if any bits plugged the tubing and switch. If you suck on the switch tubing and check continuity. You can also try bypassing the switch to verify it is the problem, but don't run the furnace like this for long. Any debris that got down inside the switch diaphragm may force you to buy a new one.

zbitner · Jan 20, 2009, 12:46 PM

That is a great idea. I didn't think to check the tubes for debris. I'm sure there's something in there. I just need to get it running tonight for my own mental health. I understand that it is dangerous to run without the switch.

zbitner · Jan 20, 2009, 05:05 PM

What happens if you run the furnace without the pressure switch?

Missouri Bound · Jan 20, 2009, 07:41 PM

The furnace shouldn't fire without the pressure switch. It's a safety feature that won't allow fire unless a draft is proven. Did you reset the circuit board after the repair? (power off and on)

dac122 · Jan 21, 2009, 09:36 AM

Originally Posted by zbitner

What happens if you run the furnace without the pressure switch?

It is a safety device to protect your life and damage to your equipment. If you don't have proper draft and the switch isn't stopping your furnace, any number of bad things could happen. We could count the ways but I digress.

My lawyers tell me to recommend bypassing for diagnosis only, no exceptions! Running it that way for any extended period gets you nominated for a Darwin Award. :)

zbitner · Jan 21, 2009, 03:44 PM

OK, I've replaced the pressure switch and I'm still getting the three blinks. The inducer is running fine. Is there anything else that could be causing this code? The two tubes are clear of debris.

mygirlsdad77 · Jan 21, 2009, 05:07 PM

If you can get your hands on a vacuum gauge, you can test to make sure draft inducer is pulling sufficient vacuum. If its not, you either have a venting problem(plugged vent) or a weak motor(may seem to run strong, but may not be 100%)

Original probem was either caused by set screw that holds the wheel on shaft coming loose, or bearings in motor were worn causing wheel to have too much back and forth play. This would also explain motor not running to full strength. Let me know what you find.

One more thing, make sure to check that port where tubes connect are clear. If the port on the inducer housing is plugged partially, it will cause this.

hvacservicetech_07 · Jan 21, 2009, 06:07 PM

Are you sure that the tubes that run between the pressure switch and inducer fan are connected back correctly? Maybe you didn't get something hooked back up?

Missouri Bound · Jan 21, 2009, 06:14 PM

How does the board determine if the pressure switch is open or closed? Are there leads going to the board from the switch? It's easy to determine if the switch is open or closed with a meter if this is the case. If the switch proves to be closed, then you have a bad connection somewhere or the board is bad. No reset on the board?

zbitner · Jan 22, 2009, 07:43 AM

I am certain the tubes are run correctly. From the pressure switch one lead goes to the limit switch and the other goes to the board via a large 12 prong plug. This is the board if that helps, 031-01267-001. The high limit switch was replaced about two weeks ago. Does resetting the board just involve shutting the machine off and on? If so that's been done a few times. Well if it gets to me getting a hold of a vacuum gauge I might need to get pro help. I feel like I'm so close. I've taken a lot of variables out of the problem.

Assuming the switch is good and the tubes are clear the only other things it could be are bad/slow inducer motor or plugged vent? I can run something down the intake exhaust pipes,but they're about 6 ft of pipe each I suppose. Does any of this info change anything?

dac122 · Jan 22, 2009, 07:54 AM

I think you need to be a little more methodical about your approach or at least tell us a little more. If bypassing the pressure switch gets the unit to work correctly then the problem is there or upstream. If that doesn't get the unit to work correctly then the problem is somewhere else in addition to a possible upstream problem.

Tell us what you've tried so we can eliminate certain possibilities.

zbitner · Jan 22, 2009, 08:09 AM

OK,
I ran the furnace with the original pressure switch after replacing the damaged inducer wheel. Then there was a three blink code and no fire.

Ran the furnace without the switch and the gas lit like normal.

I checked the two tubes and ports from both the burner box and the inducer. They are clear.

I replaced the pressure switch and ran the machine only to get the same code. That is where I have stopped.

This would not have anything to do with having the sheet metal exterior peeled back would it? That would not affect the vacuum right? I'm not referring to the ducts, but the housing around the furnace.

dac122 · Jan 22, 2009, 08:17 AM

Okay thanks for the update, and it sounds like you are close to the problem.

Not sure what you mean by sheet metal exterior, but that pressure switch measures vacuum in inches of water column (IWC). IWC is not much vacuum, so even a small leak or the inducer fan not pulling enough will keep the switch from closing. The switch should have a spec and to measure IWC you need a special tool.

If you cannot find the final problem at least you can direct an HVAC pro to the exact spot so the service call will be shorter and less costly.

mygirlsdad77 · Jan 22, 2009, 06:48 PM

Make sure the new pressure switch is exactly the same as the old. You are very close. I think it is indeed time to call in the pros. You have already located problem(roughly), and it will save you money on your service call. Good job. And please let us know how things work out.

zbitner · Jan 26, 2009, 07:31 PM

Didn't call the pros. We now have heat. I fiddled with the inducer seals a little more. All I had to do was press the inducer into the unit more. It wasn't sealing proplerly. So right now it's working. Thanks for all the great tips.

One other small question, I hooked up the blower motor again and it didn't seem to be spinning as fast. I was looking at the diagram and couldn't make much of it. As soon as I unhooked the red wire from the FAC? It went to a higher speed setting. I plugged it into the PARK prong and it seems fine. I'll do a little more research, but does it sound like it's OK if it's spinning at the right speed? Motor # 024-23271-000 circuit board 031-01267-001.

dac122 · Jan 27, 2009, 07:10 AM

Originally Posted by zbitner

Didn't call the pros. We now have heat. I fiddled with the inducer seals a little more. All I had to do was press the inducer into the unit more. It wasn't sealing proplerly. So right now it's working. Thanks for all the great tips.

One other small question, I hooked up the blower motor again and it didn't seem to be spinning as fast. I was looking at the diagram and couldn't make much of it. As soon as I unhooked the red wire from the FAC? it went to a higher speed setting. I plugged it into the PARK prong and it seems fine. I'll do a little more research, but does it sound like it's OK if it's spinning at the right speed? Motor # 024-23271-000 circuit board 031-01267-001.

Glad you got your inducer running. As expected you had some kind of leak reducing the needed vacuum to close that switch.

If you have a 3 speed blower fan then black, blue and red are high, medium and low speeds respectively. Park is a dead terminal to hold the extra wires from swinging in the breeze. You cannot energize multiple speeds at once unless you like smoke. Not sure why you unplugged the blower, but you need a minimum fan speed to keep your heat exchanger from overheating. To high is okay if you can handle the noise.