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American Standard Gas Furnace


TomBurns's Avatar
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11-13-17, 04:06 PM   #1 (permalink)  
American Standard Gas Furnace

Hi I purchased a used propane furnace. I hooked it up to test it and the chimney fan came on but not heat. While checking things I shorted the limit sw. to ground now the chimney fan wonít start. I donít see a fuse anywhere. The red light is blinking steady on the control panel. Did I possibly blow the low volt transformer?

 
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11-13-17, 04:19 PM   #2 (permalink)  
First, since you purchased used equipment, is the heat exchanger ok and safe to us in this unit? Is it converted to LP?

 
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11-13-17, 04:42 PM   #3 (permalink)  
The red light is blinking steady on the control panel.
Blinking steady ? Blinking what steady ?

That light serves as a fault indicator. The flash codes are listed on the back of the blower door.
If the red LED is flashing.... the transformer is ok as the board runs on 24vac.

An AS furnace should be using a control board with a fuse. It is a plastic type automotive fuse somewhere between 3-5A.


~ Pete ~


Last edited by PJmax; 11-13-17 at 08:37 PM. Reason: typo
 
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11-13-17, 04:58 PM   #4 (permalink)  
Gas Furnace

Yes the red light blinks on off on off and not blinking codes. The board in my furnace does not have any fuse I can see. The furnace was used with LP prior and the heat exchanger is OK. The unit was running prior to being removed.

 
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11-13-17, 08:40 PM   #5 (permalink)  
In order for me to help you further..... I need a model number for that furnace. It's inside on the side wall near the burner. You could post the model number off the control board too.

I would have expected a fuse to blow... if there was one. A quick short usually won't hurt the transformer. You could check the sensor you shorted. There should be 24vac on both sides of it measured to ground. Normally if the limit circuit was open..... you'd get a dedicated fault for that. A bit of a mystery here.


~ Pete ~

 
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11-14-17, 10:46 AM   #6 (permalink)  
American Standard Furnace

Furnace Model AUD140C960A1
Control Model 50A50-405

if I jump out the t-stat the chimney fan works
and I now am getting a three blink code
(Pressure Sw.)
I am getting a 27vac at both sides of the limit
sw.
Most likely when I shorted the limit sw. I burnt up the t-star?
There is three wires on the pressure sw two yellow have 27vac and no voltage at the orange wire with the fan running. Hope this helps. Thanks

 
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11-14-17, 11:24 AM   #7 (permalink)  
The pressure switch won't close without the proper vacuum on it. That requires the proper flue connected to the furnace. On a call for heat..... just as the draft inducer starts..... you can short the pressure switch and see if the furnace continues with the ignition cycle.


~ Pete ~

 
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11-14-17, 11:39 AM   #8 (permalink)  
American Standard Furnace

Add info.
I checked the pressure sw with an ohm meter and itís working ok but I have no vacuum at the hose at all.
I put a wire through the hose into the fan plentym but still no vacuum?

 
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11-14-17, 11:44 AM   #9 (permalink)  
Yes it will continue and the ign. glow l comes on but propane valve is not opening. I currently have it hooked up to a propane tank with a gas grill regular to test unit prior paying to have it installed?

 
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11-14-17, 12:06 PM   #10 (permalink)  
American Standard

the valve did open and gas valves lit off but week orange flame for a few seconds and they go off, Iím sure the regulator is not enough.

 
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11-14-17, 01:42 PM   #11 (permalink)  
American Standard furnace

I did put a T exhaust pipe on the exhaust with a barometric vent, would it need more to create the needed pressure to create the proper vacuum for the pressure sw?

 
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11-14-17, 04:15 PM   #12 (permalink)  
The fan was missing half of the blades.

 
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11-14-17, 04:46 PM   #13 (permalink)  
This sounds like a purchase to pass on.


~ Pete ~

 
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11-14-17, 07:40 PM   #14 (permalink)  
The inducer fan is missing blades?
I’d pass on this furnace.

 
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11-15-17, 05:05 PM   #15 (permalink)  
American Standard Furnace

So if anyone has a bad fan on their inducer motor should get a new furnace?

 
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11-15-17, 07:44 PM   #16 (permalink)  
No, but if this unit is already busted up and you haven’t even installed it yet, it may be best to keep looking.

 
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11-15-17, 07:56 PM   #17 (permalink)  
You won't have any vacuum on the pressure switch if the inducer is missing blades. The vacuum level cannot be felt with your finger. You need to use a manometer.


~ Pete ~

 
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11-18-17, 02:22 PM   #18 (permalink)  
American Standard Furnace

PJ you led me in the right direction thanks you for the info. After changing the fan wheel for 30 bucks the furnace runs great.

 
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11-18-17, 02:26 PM   #19 (permalink)  
That's great news. Good job.


~ Pete ~

 
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