Furnace not heating

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  #1  
Old 11-27-02, 05:22 AM
Henry2
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Furnace not heating

Hello! I have an Arcoaire central central air unit with gas furnace model #GNI060A012AIN Manufactured in Jan '92. It is connected to a honeywell programable thermostat. The furnace is located in the attic. It is not heating when the weather gets cold. This model does NOT have a pilot. The burners should be fired directly by a glow type igniter. The igniter appears to glow fine and I have replaced the flame sensor. Sometimes the burners will lite up and heat up. Once the desired temp is reached, and the unit shuts off, it may not fire up again. The inducer comes on fine each time. The code I'm getting from the conrol module is one flash repeating every couple of seconds which appears to mean "lockout due to retry". Sometimes, I can disconnect power and reconnect and it will work fine for a while and then stop heating again. I've jiggled connections but have not been able to get it to heat consistantly.

I've looked at a number of the previous posts and want to test the different components. Should I have the furnace on when I'm connecting the voltmeter to the various conponents? Logic tells me that to measure current, you have to supply current but I don't want to make any wrong moves.

Also, even though the igniter glows each time until lock out occurs, is it possible it isn't getting hot enough? Visually, it looks and glows fine and I can feel the heat from it about 18 inches away. Please help. We're getting our first freeze of the season. Thanks!
 
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  #2  
Old 11-27-02, 02:52 PM
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Hello Henry2 and Welcome to the Heating and Cooling forum.

Always the possibility the module is defective, a poor connection somewhere, the ignitor is weak or the gas valve is defective.

The most likely cause is a weak glow coil. If it's orange in color while glowing, then it is not glowing hot enough to function correctly.

A hot glow coil, working correctly, will glow an intense bright yellow orange in color. Too much orange, any reddish color or a dull orange means the glow coil is weak. Replacing it should solve the problem.

System lockout may indicate flue vent blockage, exhaust fan failure, ignition failure, low voltage failure, safety device or system failures or any other sort of defects, etc.

Electronic ignition furnaces are complex units which may not be serviceable by the do-it-yourself person. Professional help may be required.

Retail parts dealers can also help determine what the possible problem may be. Bring the make, model and serial numbers if you stop in at the store. The info will help to determine the ignition system and possible problem causes.

If you need further assistance, use the REPLY button to add any additional information or questions, etc. Using this method also moves the topic back up to the top of the list automatically.

Regards & Good Luck, Forum Host & Moderator.
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Old 11-27-02, 08:05 PM
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common problem

not always common answer, unfortunately. i have run into MANY calls like this recently, and only able to go from what i see. 1) if the HSI (hot surface ignitor) is glowing, in my experience it is good, do not remember seeing one "not hot enough". not to say this is not so, just i have never seen it. 2) you have ruled out the falme sensor 3) how about the pressure switch? can you determine it it maintains continuity when failure occurs? if so, rule it out. 4) many times the board fails during colder weather, in my opinion, due to expansion/contraction. just my 2 cents
 
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Old 11-27-02, 09:19 PM
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Hello: Henry2

hvac4u makes a good point. I should and do need to clearify my statement regarding a hot surface glow ignitor not glowing hot enough. I hope to do that here.

By this I mean and hope to be able to explain here, the ignitor is glowing and appears to be functioning but simply not glowing hot enough to provide positive source of ignition to the gas.

Ignitors work on a resistance value to electrical current. They absorb {use} the houseline current available an change the resistance value of the current.

In doing so they send a small amount of current to operate {signal} the module. The chain reaction then starts until all systems prove themselves. The control circuit board monitors the system and determines the results of the signal back to it.

When all systems are operational and ready, the gas valve opens and burner gas is allowed to flow. The positive source of ignition is the ignitor and it ignites the gas. The self testing systems will continue throughout the complete furnaces operational time.

Not familar with really cold damp or moist weather or climate zones. Nor exactly familar with how a furnace will operate under those conditions nor in all cases.

Weather and temps will effect almost all electronic systems and componets at some time. Ignitors are no exceptions. Age plays a part in there operation and climate can also be a factor.
 
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Old 11-27-02, 10:34 PM
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Commonalities

Ignitor.....cheap fix, almost anyone starts there. Homeowner can do this, I give it 2 hammers....
 
  #6  
Old 12-01-02, 10:23 AM
brokenfurnace
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Lightbulb Did you try a new control board?

My unit had a similar problem with yours.
I replaced a flame sensor and a ignitor but the problem remained the same. Finally I had to call a pro in. He by-passed the pressure switch and it worked right away.
I am not sure if you replace the control board, your unit will work, but according to your description, I think the control board can cause the problem and in my case, it was. The control board is very expensive, and I do not think you can return the board to the store after buying it, so you should think about it carefully before you buy it or call a pro over.
Here is my final thought: Can you by-pass the pressure swith? Turn your unit on, let it run and try by-pass the pressure swith, if the flame comes on right away. I am very sure the board is bad and it needs to be repalced.
Good luck.
Brokenfurnace.
 
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Old 12-01-02, 06:55 PM
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pressure switch

I would never recommend you jump out the SAFETY pressure switch, especially if it is doing what it was designed to do. You might want to see if there is a birds nest or old bee hive in the flue. This is a common cause...If you want to know if this is the problem, put a meter across the terminals and see if switch is opened or closed. If you don't have the tools to do the required work, call in a service tech.
 
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