# Furnace will not stay on



## allenzachary (Dec 16, 2006)

Just replaced inducer blower. Prior to replacement of inducer, unit did not react to thermostat at all.

Now Inducer blower comes on, about thirty seconds later a relay clicks, then the furnace flame begins burning. Another 30 seconds or so, the blower comes on that delivers the forced air to the house. 

Heat stays on for 1 to 5 minutes, then shuts off well before thermostat temperature is attained.

Details:

Columbia, South Carolina, Average Winter high 56, Average Winter low 37. 

Ranch home on slab, HVAC in attic. Natural gas supplied A/C and furnace in the same unit, by Inter City products Corp Model DGHH075A012IN, at least 12 years old. Honeywell CT3400A electronic programmable thermostat, same age.

Acefurnacefixer will say to call a pro, any other suggestions?


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## #CARRIERMAN (Oct 18, 2006)

Hi allenzachary

I will go over a few possibilitys, First and foremost. Is the filter clean?. If this is a yes. Reading your earlier post I will bet you have a voltmeter. In the middle of the furnace will be a black limit about 2"x 3.5" with two leads coming off of it. Put a meter lead on either side and see if this limit shows voltage when the furnace shuts off. If it does you could have a partially plugged evap coil, blower not running up to speed, etc. With your back ground you should have no trouble determining this. If you find you have a limit opening during your heat cycle. Then I would reccomend having the pros come in and fix your problem. If this is not the problem if you will give me a little more detail we will nail it down.

Good luck 
Rusty


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## allenzachary (Dec 16, 2006)

I have filters in the two returns, one at either end of the house. I'm embarassed to say that the filters are not terribly clean. Shame on me. I'm heading to the 24 hour store to get replacements.

I've attached a picture of what I believe is the limiter you mentioned. I couldn't get a reading across it as my multimeter's battery died, (when it rains, it pours). When I disconnected one of the leads to get to it, though, it engaged the main blower fan (terminology? the fan that forces the air through the vents) and nothing else. I also noticed in the photo that there is soot surrounding the "limiter" as if it either burnt up or smoke was forced out through the tiny gap between it and the furnace. Is this normal, as an accumulation over time, or symptomatic of a sudden failure?

The (new) inducer blower is blowing constantly whether the whole system is runing or not. 

I'm off to Wal-Mart to get filters and a battery for my meter. (I believe that's the single advantage of having Wal-Mart infest my town... hardware late at night).

I'll update you with a voltage measurement when I get back.

Thanks for your help.

AZ 
SC


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## allenzachary (Dec 16, 2006)

oops...the picture.


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## allenzachary (Dec 16, 2006)

OK...

Filters replaced with sparkly clean new ones...

Tested limiter with furnace off, (circulation fan off, no flame), and it shows 0 volts.

Could this have something to do with "cleaning" the unit. I'm embarassed to say that I've never cleaned the furnace or even thought about it.

Meanwhile, the inducer blower continues to run, as it has since I replaced it around 6PM today. Perhaps that is why the old one died...it was running constantly.

I await your response with baited breath, (and chattering teeth)

Allen


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## Aceinstaller (Feb 11, 2006)

try turning your thermostat down or off, then check to see if the inducer motor is still running.

this motor will run when the t-stat is calling for heat, but if it's running when there is no call for heat then you either have some miswired components or a bad circuit board.

if it shuts off when you turn your t-stat down, then turn it back up and post exactly what the furnace is doing as such:

1. inducer motor starts yes/no

2. ignitor glows, or spark ignition is working yes/no

3. main gas valve opens and burners light yes/no

4. burners stay lit for longer than 30 seconds yes/no

5. main blower motor starts and supplies home with air yes/no

knowing which spot in the furnace cycle that you circle "no" will allow me to help you efficiently solve your problem.

Ace


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## allenzachary (Dec 16, 2006)

Inducer motor shuts down about 30 seconds after setting t-stat to "off."

The answers to your troubleshooting questions have changed since last night. Last night the system cycled on and off in short bursts and got the house marginally warm. The burners shut off in less than 30 seconds each time, thus:

Last night:

1) yes 2) yes 3) yes 4) no 5) yes

I tried the inducer motor experiment this morning around 5AM. Since then the answers have changed:

1) yes 2) no 3) no) 4) no 5) no

Weird, huh?

Thanks again to all for assistance.

Allen


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## #CARRIERMAN (Oct 18, 2006)

Hi allenzachary

On the board you connected the inducer too should be a ATO fuse. Check the fuse and make sure it is ok. Use your voltmeter on the Ohm scale. Unplug your furnace, disconnect one side of each of the limits. Test across the limits with your meter. If any of the limits show infinite, that limit is open. There is now doubt that you have a 24 volt problem, we just need to locate the source. It could be a resetable limit that is open. Let us know and we will help you figure it out. You could have a pressure switch not holding. The problems listed on the previous response would point more to that being your source. To determine this, get a jumper wire. Locate the pressure switch. Start the unit up, place the jumper wire across the pressure switch terminals. If the unit fires up and runs. Replace the pressure switch.

Good luck
Rusty


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## allenzachary (Dec 16, 2006)

Results...

Looked carefully at the PC board...there is no fuse of any type as far as I can see. No blades, no glass fuses.

The only limit I see is the one in the photo in the previous post. It reads 0.5 ohms. When I disconnect one of the leads on the limit, the circulation fan comes on, so there is clearly some kind of effect the limit is having. My guess is that it's working as it is designed.

I also tried the jumper on the pressure sensor...here's where the fun starts. When I jumped between the leads with the unit powered up, it began the normal heat cycle; the flame fired up and about 20 seconds later, the circulation fan came on. When I removed the jumper, the system shut down. It seems that this is the source of the problem.

Now the questions come:

1) Do you agree that the pressure sensor seems to be the culprit?

2)There are two pressure sensors mounted on the same bracket. I only bypassed one of them. The one that I bypassed has two vacuum tubes connected to it, the other has only one. Do I need to replace both or just the one that worked when it was bypassed? Would a photo help?

2) Are pressure switches as particular as inducer blowers? Are there many types/models/brands of pressure sensors? Would I get tthem from the same HVAC suppliers as the inducer blower?

Thanks again....

Allen


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## caseywa (Nov 7, 2006)

Just my two-cents, if I may...allenzachary, you said on your previous post:

"2) On the old unit, there is a condensate line connected in the top left quadrant along with the drain line connected to the bottom. The new unit has a nipple in each the top left and top right quadrants. Am I to connect the line to the top left? Would I have to punch through the nipple?"

On my inducer like yours the bottom clear plastic tube is the condensation drain and the top left hose is to the pressure switch.

Is it possible that either the top left nipple is not going to the pressure switch or that this nipple is not "drilled" out into the inducer housing?

Will the pressure switch not being able to sense air pressure from the inducer cause these symptoms?


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## allenzachary (Dec 16, 2006)

Casey-

That was my though as well, so I took the inducer off and disassembled it. Alas, it was "drilled through."

All the research I'm doing is saying the problem is not the pressure switch. They are nearly impossible to cross reference and even harder to find available to buy. If they often went bad, they would be much more prevalent (like our old friends, the inducer blowers-everyone stocks and sells them). 

Although I find sleeping temps in the upper 50's quite to my liking, (along with the lack of a heat bill), my wife and daughters are growing tired of being "cold" while Daddy struggles with the monster in the attic. I may give in and call a pro. I'm at my wit's end. 

I know to my bones the answer is something incredibly simple and it will cause me great pain to hand over $100+ to a guy who says, "Oh, you didn't do this," and watch him flick a switch or connect a wire. The only problem is I don't know what incredibly simple solution may be.

Today is my last chance. My wife said this morning "So, today you'll call the heating guy?"

Frustrated in SC.
Allen

PS: Did you get that blower wheel to BDNPA? I also have a spare for him.


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## #CARRIERMAN (Oct 18, 2006)

Hi allenzachary

We just had this happen on a brand new unit that someone installed. We were able to fix the problem with replacing just the one. But before you do you need to make sure you are not ponding water in the exhaust first. If there is no problem there, you should be good with just replacing the pressure switch. And yes they are mostly unit specific.

Good luck 
Rusty


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## askme233 (Dec 19, 2006)

I'm a newbie here, but Allen Zachary is my son's name so I figured I would post.

I also had similar problems that frustratingly would change somewhat over time. Same difficulty starting (staying started) that if I played with it I could get it to work.

We thought it was various sensors (bad flame sensor?), checked them all. In the end, and after much frustration, it turned out to be the main control unit. A simple LED light on the unit indicated a fault. replacing the unit ($100) cured all of the problems.

ASK


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## zloy (Dec 28, 2006)

allenzachary said:


> Heat stays on for 1 to 5 minutes, then shuts off well before thermostat temperature is attained.


I have a similar problem. The difference is I have not changed anything recently (I just bought a house a couple of months ago), I have Concord. In my case, it shut off when I try to heat above 65-67F. It held last night 63F, but shut off in the morning insted of going to 72F. 

If I switch off - switch on the heater then it works for 5-15 min and shuts off again. A simple LED light on the heater indicates the "system lockout" fault. It started this Tuesday. 

Any suggestion?

Thanks for your help.


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## caseywa (Nov 7, 2006)

Allen...my blower wheel is damaged and was about ready to tilt. Get ahold of Brad about your wheel. I have his direct email and will get a message to him now.

Casey


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## BDPNA (Nov 27, 2006)

*Blower Wheel!*

Hey Allen,

I could still use that blower wheel for sure -- Would save me the hassle of having to use the completely new inducer motor!

If you get a chance, do reply to this thread or send me a Private Message with your email -- I will send you one now as well. Thanks!


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## allenzachary (Dec 16, 2006)

*Had to Call in a Pro...*

Narrowed it down to one of three problems:

1) Pressure switch(es) gone bad.

2) Clogged flue

3) Bad circuit board.

Ran outta time. The weather in good old SC was warm for the previous week and a half and my wife was supportive of my DIY activites. Then suddenly, the temperature dropped and, nearly as quickly, my wife's patience disappeared.

I had a real struggle finding a replacement pressure switch on the net. Finding a inducer blower was easy by comparison, which made me doubt that the problem was the pressure switch. If a parts breaks a lot, it must need to be replaced a lot; if not, there is much less call for it and thus it would be less available, right? Wrong. Turned out the problem was indeed one of the pressure switches. 

$185 got the part and labor done, which wasn't bad, considering the average cost of the pressure switches I actually found was around $130. 

Thanks to all for the help. 

Allen

PS. I sent the blower wheel to Brad


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## caseywa (Nov 7, 2006)

Sweet!


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## sloooo (Dec 19, 2006)

I saw this post to late. You could have gotten your pressure switch for your unit for about $30 to $40 bucks at a local parts house. Next time you need any parts, look up United Refrigeration on your computer and search for a store. They are in every major city and so far the most anyone has had to drive was 55 miles to get a part.


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## allenzachary (Dec 16, 2006)

"I saw this post to late"

I guess that's why you are called "sloooo." :no:

No worries, and no regrets. Once it got to a choice of several possible secondary problems, especially with the weather turning cold, I felt calling a pro was the right thing to do.

I saved at least $150 on the inducer blower, which was the obvious primary issue. When that didn't solve it, I suspected the presssure switch, but was unable to confirm completely on my own. I didn't want to keep buying parts and stabbing in the dark (and cold).

The United Refrigeration is a good tip. I'll keep it mind the for the next time. thanks.


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## notorious.dds (Jan 10, 2007)

allenzachary said:


> The (new) inducer blower is blowing constantly whether the whole system is runing or not.


I was having a similar problem with my furnace. It would work fine for a while and then at random times when it tried to ignite, it would go into error mode. The error on the ignition module read "pressure switch stuck closed". So, I replaced the pressure switch (PS), but it made no difference. 

It wasn't until then that I noticed the inducer running constantly when the furnace was in error mode. Once it went into error, the inducer would run even when I lowered the temp at the thermostat below the standing temp and even if I switched the heat to "off" at the thermostat. At that point, I opened the blower panel, held the blower panel safty switch down and tapped on the ignition module (IM). After a few taps, the inducer shut off. Voila, it was my IM. I replaced that and have been problem free since. 

If someone reads this and isn't sure if they have bad PS or bad IM, you can test your PS pretty easily. Among other ways, there is one listed toward the bottom on the page http://arnoldservice.com/Troubleshooting_He[URL="http://arnoldservice.com/Troubleshooting_Heating_Problems.htm"]ating_Problems.htm[/URL]

I hope this helps someone who's wife won't get off his back because he's bound and determined to get the damn thing fixed himself even if ice is beginning to form on the old lady's nose.:furious:


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## smallcrpt (Jan 15, 2007)

*hmm*

i was going to post this exact same title in a new post.. glad i browsed and searched... first off, i'm a newbie to homeowning. so gimme some leeway. 

our oil burner/furnace that heats the house through baseboard heat isn't igniting as it should. when the temp drops in the house, in either of the two zones, the heater starts up. then the ignitor starts, but quickly goes off. this happens a few times until it finally goes on and works correctly

we had our furnace serviced late last year and i poked around and couldn't find a filter to see if was trying to ignite but getting choked out... any ideas?


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## SnoBird (Nov 27, 2006)

IGNITER PROBLEMS
At our previous house, we had an Ammana furnace with a glowplug type igniter that would only last a few months. A furnace man advised my wife to not use Tide soap for the laundry. Changed to another brand. Sounds crazy, but the igniter lasted much longer after the change!


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## jbac (Jan 18, 2007)

try disconnecting hose from pressure switch and whatever else hose is connected to and ream out the ferrules that the hose is connected to. use a piece of uninsulated thermostst wire.


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## caseywa (Nov 7, 2006)

SnoBird...curious about the Tide laundry soap, but made me think. Did the furnace man give you any further explaination about this? What I wondered about if it was possible that one of the chemicals used in the laundry soap was released into the air in minute particles when being used and found its way into the air system to the glow plug. If the light dusting that continued to occur on the glow plug created a further chemical reaction when the plug heated resulting in a slow failure of the plug over time. Hmmm.....makes for an interesting discussion. Any latent chemists out there?


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## smallcrpt (Jan 15, 2007)

*not exactly sure...*

i've got a teledyne laars - mini-therm jf oil furnace with a reillo 40-f3 oil injector pump.

i dont know if either of those help anyone, but its happening worse now, i'm just glad its not broken, i'm going to have to resort to asking my neighbor for his furnace mans name unless someone can give me a walkthrough in cleaning/repairing it. 

we conveniently just switched from a home heating oil company to a local BP gas station that delivers at a much lower cost.. so i was also thinking that this home fuel oil #2 is different or "dirtier" where its messing up something...

thanks
smallz

ps, also our heat is loud, like expansion creaking and cracking all the time.. is that normal? as i said before i'm new to home owning, if it didn't happen in my old house i wouldn't know..


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## Motorace (Jan 6, 2009)

*Blower Wheel supplier!*



BDPNA said:


> I could still use that blower wheel for sure -- Would save me the hassle of having to use the completely new inducer motor!


I've got the exact same model number Inter-City/ArcoAire (~20 year old) horizontal furnace that allenzachary started this thread with. That's how I found this thread - by Googling on the furnace model number. It was working great until two days ago when the inducer blower started making a noise so loud I initially thought the neighbors were running a chain saw.

When I got the inducer blower apart, I found that a small concrete chip had been sucked into it and damaged the blower fan. I tried repairing the blower wheel but a slight imbalance just made it worse. They're somewhat fragile and extremely sensitive to imbalance at the high speed they operate at. I clearly needed a new blower wheel. 

I asked my HVAC guy for help locating another one. He had no sources for the blower wheels but said he could get the entire inducer assy. He went to get one from his supplier but it wasn't even a close match - which turned out to be a blessing in disguise because they wanted over $600!

So I looked on the web. I shoulda gone there first, but I'd hoped to find one locally to get the heat back on sooner. Googling on the Fasco/"Swirlwind" inducer blower part number (#7062-3136 seen on the label on the motor) I found that CSH Inc (www.cshincorporated.com) sold an exact-looking plastic replacement FASCO blower wheel (p/n 8710-4358) for $23.34. The dimensions all lined up correctly so I ordered one today (see photo from their website). 

Don't lose your wire-coil that clamps the blower wheel to the motor shaft because the new wheel doesn't come with one!

CSH also offers a replacement Inducer Blower assy from Rotom (# FB-RFB540) for $155.31, or an original Fasco Assy (# A168) for $225.70 (see photo below from their website). Hopefully I will not need one of these for a few more years yet.

I contacted a number of other suppliers to check their Inducer Blower assy prices too and most were over $400!

If I do not post again then you'll know the $23 blower fan wheel worked fine, but if it doesn't work - I'll post again to tell future readers what I did to solve it.


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## BDPNA (Nov 27, 2006)

Hey nice find - Let us know what happens. I still have the same furnace so it's good to know if it happens again.


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## Motorace (Jan 6, 2009)

The new blower wheel worked great and saved me a ton of money!


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## jdb (Oct 21, 2009)

*Blower Wheel Part*

Motorace, I am about to swap out a damaged blower wheel that is identical to the one you replaced. Thanks for the help locating the part.

When I took apart the inducer assembly, I noticed the blower wheel had fallen off the motor shaft, which caused the fan to bind and stop. Luckily this did not burn the motor out. However, I did not see the wire coil you mentioned. It seems like the shaft is "keyed" and the wheel is kept on by friction on mine. 

Can you describe what the wire coil piece does and what it looks like? I am concerned that if the replacement wheel doesn't come with this part I might be stuck .


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## Motorace (Jan 6, 2009)

*What does that little coiled wire thingie do?*

My Blower wheel did NOT come with a replacement coiled wire clamp - and I think I recall the seller saying something about "Don't lose the coiled wire clamp!" The fact that you say your wheel slid off the motor shaft indicates to me that friction wasn't doing the trick of holding it on.

For those of you who have a coiled wire clamp on your blower shaft - it initially appeared to be very difficult to remove - but the trick is that it 'threads' on and off - you cannot just pull it straight off the hub. There will be one direction that tightens it and the other direction loosens it.

Fortunately I took some photos of my fan assembly and related parts before putting it all back together...

The first picture is looking down into the blower wheel at the little hub sticking up in the center.

The second picture is a close up of the old blower wheel hub - showing how it has a split in the end of it - allowing the split parts to flex enough for the coiled wire thingie to 'clamp' the end of the hub more tightly to the motor shaft.

The third picture shows the motor shaft and the coiled wire thingie next to it - sitting in the housing that the blower wheel will later fit into.

You're right that the motor shaft has a flattened side and the blower wheel has a matching shape - such that the blower wheel is 'keyed' to the shaft (although there is no separate 'key' like on a lawnmower flywheel).

My guess is that the coiled wire clamp is useful to prevent the blower wheel from moving axially along the shaft - otherwise it might start rubbing against either side and making a heck of a rackety noise (like my neighbor's chainsaw - which was what I thought I was listening to before I figured out it was my broken furnace blower wheel)

I'd take the blower wheel with you to your best local hardware store - the one with the best selection of little nuts & bolts and springs (i.e. REAL "hardware" as opposed to paper plates and the latest halloween decorations)... 

Ask the owner if he stocks any special coils designed to do this task. If not, look for a short coil spring that will twist onto the split hub in one direction but not the other. Springs are cheap enough that if you have to buy several to try when you get home - do it. 

If you don't find anything that looks like it will work, you could always try some Loc-tite between the blower wheel and the shaft or try wrapping a short length of stiff wire tightly around the hub after it's on the shaft, but be careful to not throw off the balance - These blower wheels spin at very high speed and balance is a lot more critical than you might expect at first.

If you end up not using the coil wire and it works just fine without it - I'd be curious to know about that. Good Luck!


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## diyorpay (Sep 21, 2010)

*repair your fasco indiced draft fan blower yourself*

This thread has been very useful to me and has saved me money. I have an Amana furnace whose induced draft fan has failed twice before and it's never at a good time. I've had to replace the entire unit each time even though the motor and capacitor were fine. In my case, tracing back data not so available on the internet at the time, I determined the induced fan unit was an A158 for my Amana furnace.

The Swirlwind / fasco branded id fan unit is kind of junky and the plastic blades of the blower fan eventually get brittle and break off. Your thermostat will call for heat but because the id fan is jammed from broken blades, safety components in your furnace will prevent ignition and heat.

The www.cshincorporated.com website has excellent info on Fasco blowers and parts. The links are to www.fasco.com/pdf/pxx.pdf. Punch in a number where xx is to get a real catalog page by brand. Mine was p22.pdf and p48.pdf for my A158. You will have to hunt for your brand.

Motorace on 1/8/09 let forum users know that the wheel itself is now available as a replacement part for about $23. On 10/21/09 he then provides important pictures on how to disassemble a Swirlwind/fasco fan unit. Worked great for me. Much thanks to Motorace.

Even though his furnace was a different brand from mine, my wheel had the part # 8710-4358 stamped on the back. So same wheel will work for me. Saves a bundle on replacing whole unit and keeps landfill from useless waste.

After further research and logic on the cshincorporated.com website, I am convinced that this same wheel will work on a number of similar furnaces with PSC motor type and clockwise (CW) rotation. Motorace had an A168, an Excel/Ducane/York furnace or an InterCity/PMI/Valcun A145 or similar.

I am pretty sure the following units all will take the same wheel Motorace pointed out:

Amana A158 (mine for sure)
York A137, A165, A168
Rheem A136
PMI/Valcun Hart A145

Check out those catalog cuts on Fasco site. 

Thanks again Motorace.


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## Motorace (Jan 6, 2009)

diyorpay said:


> Much thanks to Motorace.
> 
> Thanks again Motorace.


You're welcome - and thank you for the kind acknowledgements! - Dan


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