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-   -   Furnace fan don't stop blowing. (http://www.diychatroom.com/f17/furnace-fan-dont-stop-blowing-15806/)

wind image 01-18-2008 08:48 PM

Furnace blower does not stop working.
 
Hey all.

My furnace is working well, but just one problem. whatever I switch Fan switch on thermostat to ON or Auto, the Blower is always working, never stop. (when the switch is at Auto position, when burner is not working, the blower is not working too, right?). I checked the furnace, the statuse light on control borad, was flashing rapidly. Do I have to buy a new PCB?

Any info will be very appreciated and thank in advance.

Goodman Furnace
M#: GMPN100-4
S#: 9609827252

wind image 01-19-2008 04:57 PM

Even I turn the system off on the thermostat, the blower is still working. is it strange?

chris75 01-19-2008 05:00 PM

Quote:

Originally Posted by wind image (Post 90013)
Even I turn the system off on the thermostat, the blower is still working. is it strange?


Sounds like a short between R and G... check the fan relay and see why it has power applied to the coil...

wind image 01-19-2008 05:05 PM

Quote:

Originally Posted by chris75 (Post 90014)
Sounds like a short between R and G... check the fan relay and see why it has power applied to the coil...

I could not find which one is fan relay. What should I do? Pls give me some instruction!!!! pls!!!!

UBoiler 01-19-2008 05:17 PM

There are an abudance of recent postings with excellent advice and trouble shooting your problem.: blower fan keeps running. Please read them. I am confident you will find your solution there. Please let us know how everything plays out and don't be hesitant posting if you don't find those similar recent threads with your solution. Or if you have more questions. Good luck. Cliff

UBoiler 01-19-2008 05:36 PM

I am not an electrician.

Fan relay: Do you have a circuit tester or electrical meter (multi-meter) and know how to safely use it? Does your furnace have a electric schematic chart that you can read? The reason I ask this is because the blower and its relationship to the furnace is diagrammed on the electrical schematic and that chart will show you what switch or relay controls it and it will show where in the electrical stream its place is. The schematic will also tell you the voltages of different parts of your circuit so you will know what setting to have your tester at. A blower will probably be at 110 v.

Without touching anything you should be able to follow the 2 wires from your blower to the source of the electricity that powers your blower. That's the switch or relay.

chris75 01-19-2008 05:56 PM

knowing how they operate to begin with is a big + also...

could be a stuck relay, something miswired, a post purge, etc...

wind image 01-19-2008 06:07 PM

Thanks Uboiler & Chris75 so much! I have a electrical meter, and I know how to use it correctly. THere is a Chart, but not show what they are one by one. And all them on the board, hard to follow the wires to reach it. I have try to replug leads to prevent not contacted properly.
Maybe I really have to replace the control board?!

UBoiler 01-19-2008 11:09 PM

Howdy Wind Image. There are a lot of threads about thermostat settings and explanations. Also about blowers that stay on. Please look for them. They'll help and they're from pros who have forgotten more about hvac then most of us ever hope to learn.

You said you have a blinking light? My control has two LED lights that flash codes and I have code guide that explains what they indicate. Maybe that helps.

About replacing your control? Maybe your control is getting a signal to turn blower on and replacing control just gives you a new control and problem continues? Look up this sites archives.

Good luck. Cliff

bigMikeB 01-20-2008 10:57 AM

The fan relay on that unit is part of the control board, no you can't physically check it. You need to call someone out and have it repaired correctly. Never change out a part that hasn't been properly diagnoised as the problem.

wind image 01-20-2008 03:16 PM

Thank you guys so much!

biggles 01-20-2008 05:29 PM

FIRST.......pull the stat of the subbase>>>>>>>>>NO FAN.... its the stat calling the fan all the time,FAN still runs next step(leave stat off subbase) SECOND with the fan running heat or no heat...down at the furnace...remove the stat wire from G or if it is GREEN from that terminal if fan shuts off you have a short on R-G from the unit to the stat....if it still runs the relay board relay for the fan is arced shut need a new board.

wind image 01-20-2008 06:23 PM

Quote:

Originally Posted by biggles (Post 90377)
FIRST.......pull the stat of the subbase>>>>>>>>>NO FAN.... its the stat calling the fan all the time,FAN still runs next step(leave stat off subbase) SECOND with the fan running heat or no heat...down at the furnace...remove the stat wire from G or if it is GREEN from that terminal if fan shuts off you have a short on R-G from the unit to the stat....if it still runs the relay board relay for the fan is arced shut need a new board.

yea, I removed the green wire (from stat) from G teminal, the fan still running. It means the fan relay is stuck, right? ha, finally. Thanks very much.

wind image 01-20-2008 06:39 PM

I removed all 3 stat wires(red, green, white) from the board's terminals, and the fan was still running. It must be the fan relay is stuck, right?! I believe so. Thanks for all your guys's help, thanks so much. At least, I found out the problem.


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