Amana 96% Furnace failure


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Old 01-25-13, 11:30 AM
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Amana 96% Furnace failure

Hello. This is my first post. The topic is somewhat outside of my expertise.

I have an Amana AMV9 96% eff. furnace in my home. It is about 6 years old. Actually we have 2 furnaces (one on each end of the bldg) but the Lennox is working fine, though it can't shut off at the moment because the Amana isn't working.

The Amana problem first presented as no heat, no exhaust fan blowing, and circulating fan on continuous high speed.
I looked into the spy hole through the fan cabinet cover, and the error code is 4 blinks. I looked in the manual and 4 blinks is high limit cut off. Suspected issues might be dirty filters/air restriction, or failed limit thermostats.

Filters are new and clean. Circulation fan has some dust, but not much.
I jumpered out the centrally located thermostat, no heat, same codes. I jumpered out each of the thermostats on the fan shroud (one at each end) one at a time, and symptoms persist.

So, I have jumpered 3 thermostats, and OHM'ed the glow bar. No improvement.

When the furnace is activated, it believes it has a high temp situation, and after 15 seconds, shuts off the induced draft blower, and then speeds up the circulating fan motor to high speed.

I have checked the condensate drains for blockages, and have sucked/blown into all of the pressure switches and have always heard contacts closing.
I see no exhaust, or condensate drain obstructions
I am starting to get confused, and chilled.

Anyone have any further tests or suggestions?

Oh, lastly, we had a brown out maybe 10 days ago while the furnace was running wide open. The voltage dropped for maybe an hour, and then stopped for 8 hours. Since the outage, the Amana ran fine all week. When we hit these low temperatures, I started running the Lennox system to supplement. But it cannot be expected to keep this house warm, nor can it be expected to run wide open for 3 or more months.
 
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Old 01-25-13, 02:59 PM
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Just a heads up.

I looked at the roll out thermostats on the above furnace, and was able to reset one. ie. When I pushed the central pin of the thermostat, it made an audible "click", and upon turning the furnace back on, it lit, and is now supplying heat to my home again. Phewww.
As these thermostats are only about $8.00 ea, I am going to purchase a couple to have on hand.

But let me be clear:
The service manual in no way mentions the open roll out thermostat as a cause or source of the 4 led flashing error code on this furnace.

In hind sight, I should have reset every manual reset thermostat on the furnace while I had the power down, and the case open.

With regard to cause, I believe that the extended running of the unit caused the reset. It had been running non-stop for several months on high fire.
 
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Old 01-25-13, 08:50 PM
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Exclamation

Rollouts don't trip for no reason. Please get your furnace checked - this is a safety issue.

Continuous operation should not cause any safety switch to trip.
 
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Old 01-25-13, 09:29 PM
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Are you sure it was the rollout sensor and not the high heat limit sensor.
Maybe you have an airflow issue there.
 
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Old 01-26-13, 11:35 AM
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Amana service person went over the furnace stem to stern. He could offer no explanation. He said, "Call me back if it does it again." Meaning he was stumped I would say. $60.00 for his expertise, and my wife's peace of mind.

I'm surprised no one mentioned the additional possible reasons for the 4 flash error code.

Certainly on machinery, low voltage (brown out) causes heat issues in thermally protected equipment. I don't know if the Amana (which runs mostly on 110) has a relay that will operate below 110 volts or not. I was expecting control board damage actually. Not a thermostat reset.

I have attached some probe thermometers to the unit to take some additional readings for my edification. I want to see if I have cabinet internal temperature issues for some reason. But as it stands, the unit is clean, dust free, all connections reseated, and running. It is operating both stages. Flames blue, no odors, draining as usual.

How often do furnaces demonstrate anomalous behavior? This unit was installed 7 years ago, and have performed well.
 
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Old 01-26-13, 11:49 AM
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I'm surprised no one mentioned the additional possible reasons for the 4 flash error code.
I believe an airflow issue is an additional possible reason for that error code.
 
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Old 01-26-13, 01:26 PM
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It sounds like your repairman made a real effort to diagnose the problem and charged you a moderate fee for this effort.


Way too many repairman would make a slap dash diagnosis that was wrong and replace some $100 part for $300 which wouldn't solve the problem.


Sounds like you have an honest guy who was trying to do a good job for you. That's worth a lot, in my opinion.
 
 

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