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Author Topic: Gaas Furnace does not run.  (Read 938 times)

Offline elchucko

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Gaas Furnace does not run.
« on: January 08, 2017, 03:42:00 PM »
I have a RUUD 90 plus gas furnace that has been working OK. Last night I turned down the thermostat to 70 degrees. This AM turned up to 78. Furnace did not turn on. Turning on the fan only the fan does not run. 2 green lights on, one flashes 2x.

Offline Admin

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Re: Gaas Furnace does not run.
« Reply #1 on: January 08, 2017, 05:08:57 PM »
If you reset the furnace power does the system start at all?  I think a 2 flash might be caused by the pressure switch stuck open.  The exhaust motor should run on a call for heat.

Have you made sure there is no snow covering the vent pipes that connect to the furnace and go outside?


Offline elchucko

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Re: Gaas Furnace does not run.
« Reply #2 on: January 08, 2017, 05:42:53 PM »
I removed the front covers and while holding in the interlock switch both green lights come on. After a couple of seconds one green light flashes and I hear a relay pick The small blower motor hums. It does not turn.

Offline elchucko

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Re: Gaas Furnace does not run.
« Reply #3 on: January 08, 2017, 05:47:02 PM »
Before my first post the blower motor was making a sound like it was trying to turn as if a phase of the power was missing (?) The motor casing got very warm. Now it only hums.

Offline elchucko

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Re: Gaas Furnace does not run.
« Reply #4 on: January 08, 2017, 06:09:13 PM »
By tapping on the motor casing I was able to get it turning again but it makes a noise like motor shaft is binding with something wthin the whole blower assembly.

Offline Admin

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Re: Gaas Furnace does not run.
« Reply #5 on: January 08, 2017, 06:29:17 PM »
So are both the ventor motor and main furnace motor humming?

It sounds like the exhaust motor (the smaller motor above the main blower), is seized.  That would cause a 2 flash lockout, as the ventor motor is not running and closing the pressure switch.

You may need to replace the ventor motor assembly.

Offline elchucko

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Re: Gaas Furnace does not run.
« Reply #6 on: January 08, 2017, 07:35:23 PM »
It sounds like the smaller blower motor is my problem. Any idea the cost for a blower motor is and how long will it take to replace?

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Re: Gaas Furnace does not run.
« Reply #7 on: January 09, 2017, 06:58:54 AM »
I think your furnace model is UGJD and the ventor motor is part #70-24157-03.  You're probably looking at $100 - $200 for the part and 1 hour labor to replace it.

Offline elchucko

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Re: Gaas Furnace does not run.
« Reply #8 on: January 09, 2017, 09:43:00 AM »
I have what looks to be  a UGRB model 70625942. The furnace/heat pump is 8 yrs old. The last couple of years we've been running in bypass mode. What is a good thermostat?

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Re: Gaas Furnace does not run.
« Reply #9 on: January 09, 2017, 10:16:12 AM »
You'll need a Fasco motor part #7062-5942.

Nest makes a decent dual fuel thermostat that will control the furnace and heat pump.

Offline elchucko

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Re: Gaas Furnace does not run.
« Reply #10 on: January 09, 2017, 11:01:38 AM »
Thank you!