[KHeere]

Hello,


New to the site. I saw a post from Marty S. from 2010 where he suspects a cracked heat exchanger might be the cause of a blower motor not stopping. Does anyone know what about a cracked heat exchanger might prevent a blower motor from not turning off?


Thanks!

 

[user_12345a]

A cracked heat exchanger won't cause continuous blower operation unless it's a newer furnace and bad enough to trip the rollout.

Continuous blower operation with the stat set to auto on the G11 is caused by a failing fan/limit switch if it's the heating speed, otherwise a sticking fan relay, thermostat issue or short in thermostat wiring between G and R wire.

Are you trying to solve a problem?

G11E is 30+ years old and 65 to 70% efficient seasonal (if it wasn't for spark ignition, closer to 60%)- if you live in a cold climate i recommend getting rid of it.

 

[KHeere]

Hi,


Thanks for the reply. Yes, I have a few problems I am trying to solve to get this furnace to limp along until I can replace it in the spring. I just replaced the blower motor and it is running like a champ except that the fan keeps running. It was doing this with the old blower motor as well. I will dig into the limit switch and thermostat now. I was just concerned when I saw that post about the cracked heat exchanger.

 

[user_12345a]

If it's a g11, it's probably cracked. If you're lucky, the cracks are hairline and don't pose a major hazard right now.

Your fan/limit may have a peg you can push in/pull out to run fan continuously - check yours.

Check the pointers on it -> there's a dial with three pointers -> off, on and high limit. if the off is set too low, it may run continuously.

You can disconnect the wire going from the limit to the fan (or going to the normally closed part of the relay - there are different ways these units are wired) to see if it's the limit doing it or a fan relay. Turn off power before disconnecting.

You may not have a fan relay if there's no a/c. Unsure of G11 but a lot of older furnaces didn't come with them and contractors added when putting in a/c.

 

[KHeere]

Yea, mine is weird - no push/pull button. And I only have one pointer and it is pointing to 93. And the "dial" goes from 120 down to 90 and then fan off.

 

[KHeere]

I do have A/C. Is there a way to post pics here?

 

[user_12345a]

after u have enough posts, you can attach.

u can also upload to a third party site and post a link.

 

[Missouri Bound]

A quick question.
When you say blower motor....are you talking about the blower that circulates air when the furnace is running or the draft inducer motor? It's pretty easy to check if it is the thermostat or stuck relay. A bit of troubleshooting may save you a few bucks.
But a furnace of that age? Time to replace even it is running perfectly.

 

[user_12345a]

The G11 does not have a draft inducer.

Natural draft.

 

[homerehabguy]

Sounds like a high limit switch. I just replaced one on my furnace. You can buy them and replace them yourself. Two screws and two wire pins. Turn off the electricity first. Then get the model no. Derial no. of the furnace and then remove the old part and take it to a retailer of limit switches or you can search online.



Five minute installation. Videos on You Tube.

 

[coolair111]

homerehubguy---- the installation varies from model to model .

Kheere- if you want to do it diy through watching youtube tutorial then only follow the one that has exactly the same model and looks exactly like yours. many a times the description says the contrary to the actual product on youtube diy channels.so be on the safer side.