Need HVAC help - troubleshooting

[drewtam]

I have a gas furnace, lived here since 2006, I don't recall the age of the furnace. Furnace wont turn on now. The main house blower will turn on, but it won't output heat. A/C seems to work fine. According to the info panel this furnace is electrically ignited (no pilot).
Gas water heater and gas dryer are working fine.

I am thinking that the flue blower is broken. Its doesn't seem to turn on to start the heat cycle, and the motor is hot to the touch. I am not familiar enough with the controls to be sure I did this right.

What I tried:
Thermostat set to 90F
Access panels removed.
Pushed access panel button (the safety button).
The electronic control panel starts with LED on constant (this mean working normal)
The vent blower never turns on.
The electronic control panel light begins to blink 3 times. Info panel: "Pressure switch failure to close." Recommends checking the vent and switch.
No heat, electronics panel continuously repeats the 3 blinks.

I've also reset it by cutting the circuit breaker power. No change.


Any HVAC guys to give me advice?
Did I diagnose this correctly?

[never_retreat]

If the induction blower is not running (blowing) the unit most likely will not fire.
There is usually a pressure/vacuum switch that if not detecting the proper flow will not fire the burner. If the flue/vent is obstructed.
Take the fan apart and see if you can make it spin free.
I found a dead mouse stuck in a blower before causing insufficient air flow and noise (from the dead mouse rolling around).
Pulled it out and back in business.

[CNYCacher]

The pressure switch error is likely about the furnace not feeling the air flow it expects from the exhaust blower.    Sounds like the fan motor has something wrong with it, especially when you say it's not running but is getting hot to the touch.

[280plus]

Bingo and bingo! In the sequence a call for heat should start the induction blower which in turn closes someform of proving switch, usually a pressure switch, when that switch makes it energizes the ignition module which then stages in spark and gas. If the quick fix doesn't work get a tech out there. Do not tell him (or her) what we think is wrong with it. let him (or her) discover the answer for themselves because if we are WRONG you just might send him (or her) off on the wrong trail which will cost you more in the long run. If they haven't got it figured out in 15 minutes you want another tech. 

[drewtam]

I pulled it off, it spins freely.

[Jim147]

Do you have a screen on your flue? Sometimes a bird or something will get in the and block it.

Can you hook the little blower motor up while out of the hole? Make sure it is running.

Pull the hose off the blower housing that goes to the switch and suck on it to see if it closes. Blow through it first to make sure it doesn't have a spider nest or something in it.

Get brand, model and serial off the unit.

jim

[drewtam]

Do you have a screen on your flue? Sometimes a bird or something will get in the and block it.

Can you hook the little blower motor up while out of the hole? Make sure it is running.

Pull the hose off the blower housing that goes to the switch and suck on it to see if it closes. Blow through it first to make sure it doesn't have a spider nest or something in it.

Get brand, model and serial off the unit.

jim

I'm gonna try that tomorrow. Gotta run to Menards and get some cord.

Fasco  Industries
pn B2833001

[Ron]

He wants manufacturer/mod/ser number off the furnace.

[280plus]

If it is in fact the motor you MAY be able to match those numbers up at your local electric motor repair shop. A lot of times they'll want you to bring it in. A lot of other times the motor specific to that brand is proprietary and can only be purchased through the manufacturer of the furnace.

[drewtam]

FIXED!


When I first removed the blower and turned it by hand, it was very resistive. It must have been stuck and I broke it free. Must have had debris in it.

I powered it directly with a cord from the wall, it ran fine. I put it back together and the furnace is running fine.

[geronimotwo]

good to hear.  you may think about ordering one of those for a spare. no telling when a sticky bearing will burn out.

[280plus]

first time you tried the furnace this year?

[Jamie B]

FIXED!


When I first removed the blower and turned it by hand, it was very resistive. It must have been stuck and I broke it free. Must have had debris in it.

I powered it directly with a cord from the wall, it ran fine. I put it back together and the furnace is running fine.

Awesome! Glad that you are in business again!!

[drewtam]

first time you tried the furnace this year?

yes

[280plus]

yup, I've seen it before. Sits all summer then won't start first time you try it. You should be ok now. Till next year. if the basment is damp in the summer it can cause this. A little corrosion building up somewhere in there.

[never_retreat]

Dam, I was right and the first one to post the solution.

[280plus]

I surrender my HVAC guru crown to you sir.  Wear it well.