Inducer fan does not come on

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Old 01-03-09, 12:58 PM
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Inducer fan does not come on

I have a Nordyne GR4GA gas package unit. When it starts up the inducer fan does not start up and the status light blinks twice. I've checked voltage at the plug and get nothing, voltage at the control board is about 55 vac. The connection cable continuity checks out at 0 ohms. I don't know if maybe I have missed something. Any help would be much appreciated.
 
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Old 01-03-09, 01:12 PM
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I'd be tracing and testing the voltage all the way from the 120 volt supply voltage to the transformer, through the limit switches, the input to the cicuit board as well as to the inducer motor.

I'd be testing that to ground (G) on the circuit board, and also checking using the neutral wire of 120 volt circuits, such as the neutral side of the inducer motor plug.

It's easy to leap to conclusions, but sound diagnostic procedures involve double checking things and explaining things that don't seem right, such as the discrepancy between voltage reading at the inducer motor and the same circuit at the circuit board.

I'd probably also supply some 120 volt power to the inducer motor to verify that it will work when it gets proper power, and jumper out the pressure switch to verify that the rest of the ignition cycle would start if the unducer fan were coming up to speed and making the pressure switch. If those two things test out, then you can concentrate on an explanation for why the inducer motor wont start.

Doing those tests would take me ----oh, ten minutes.
 
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Old 01-04-09, 06:37 PM
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Originally Posted by superay56 View Post
I have a Nordyne GR4GA gas package unit. When it starts up the inducer fan does not start up and the status light blinks twice.
Haven't had much experience with gas packs and none with Nordyne but two flashes usually means stuck-closed pressure switch. The control module first checks for a open switch before turning on the inducer. If the switch is already closed (activated) the control will not start the inducer and therefore not initiate ignition. Take a look at you switch. Suck and blow on the hose going to is and see if you hear a faint click. Check it with an ohm meter (with power off) while you do this to see if it opens and closes. If not replace the switch.
 
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Old 01-06-09, 11:05 AM
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I rechecked voltage and got 120 to ground at each wire going in to the motor, then I ran the motor on 120 external power supply and it ran fine. Today i pulled the control board and there was a smoky area on the wall behind it. It looks like the smaller relay on the board popped and burned part of the solder trace next to it. I'm concered though because i want to make sure that the relay isn't just an effect of another fault in the unit. Is there any way i can check for that. Also does anyone know how to get a replacement gasket for the inducer motor. When i took the fan off, the gasket fell apart. I've googled everything that i know how to and cannot find a way to get a gasket without buying a whole motor.
 
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Old 01-06-09, 11:09 AM
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Also, I can't get my head around finding voltage at the motor and it not turning. I couldn't find a drawing to explain what the relay that burned out does.
 
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Old 01-06-09, 11:25 AM
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A circuit board failure of the kind you describe is almost certainly a defect on the board, rather than being caused by something external to the board that will recur again.

I've replaced many such boards and never had that kind of repeat issue. No guarantees on that, of course.


Hard to say about the voltage readings you report. I'm supposing you disconnected the inducer motor using the wiring clip connector, and mesured the voltage on the pins going back to the circuit board.

With the thermostat off and the furnace sitting idle, I'd normally expect no significant voltage on either pin. It might be a defect caused by the bad relay or burned circuit board, but that's just a guess.

One diagnostic approach is to consider circuit boards and such to be "black boxes." If the black box doesn't do what it's supposed to do, you don't try to analyze why, you replace the black box.

I think you have a black box there!
 
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Old 01-06-09, 06:05 PM
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Thank you so much I'm going to get the board tomorrow and replace it. do you know anything about the inducer fan gasket. If I knew what it was made from I could cut a gasket my self. still searching for it
 
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