My 3 year old Amana is giving me some serious issues. I have had 5 servicemen over now who haven't been able to fix it. The problem seems to be that after a successful heating, the inducer blower does not turn off. The unit is then unable to fire again. At this point I get the double blink from the control module that translates to "Low fire pressure switch stuck closed" Any Ideas? Help!
Check the condensate drain, hoses and pump if it has one. Like Drumbanger says, check the pressure switch. Also check the intake and exhaust vent for blockage of water or debris. All water should drain back to the furnace and not collect in the venting. Your furnace has two pressure switches, replace the low pressure switch.
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Most likely one of two issues is occurring. Either the inducer fan is not providing enough draft because it is either spinning too slowly or the impeller is damaged, or the pressure switch that the inducer motor air flow is supposed to activate is not operating properly. If the pressure switch fails to activate, the furnace will not open the gas valve and fire the ignition believing that there is not sufficient draft the vent the combustion gases.
This is a down flow unit. There is no pressure valve on this unit. Here is all the parts on this unit.
1. Manual - reset, when used.
2. Blower and blower motor
3. Relief box also known as a exhaust flue.
4. Gas valve control knob or electric switch, ON/OFF
5. Gas Valve
6. Gas burner
7. Ratting plate
8. Blower door safety switch
9. Blocked vent safeguard tube and switch
10. Gas Manifold
11. Manual limit switch (2)
12.Hot surface ignitor
13. Flame sensor
14. Inducer blower motor
15. Control board with relays and transformer.
That is all the parts. The first thing the heater gets a call from the thermostat to the control board marked W. The board sends 24v to the inducer fan relay which makes and causes the inducer fan to come on now there is a small tube that runs from the inducer fan box to a switch when the switch makes it sends power to the board which proves you have cleared the exhaust flue then the flat surface ignitor starts to glow and then gas valve opens and fires. now if this tube is stopped up the heater will not fire and will lock the unit out. Also if the flue is stopped up with trash it will do the same thing. If you are not familiar with gas heating units you should call a service company out and check out the system there is a lot of things that need to be checked out every heating season as to keep you and your family safe.
Are your air filters relatively new? Is a bird nesting in your units combustion air exhaust pipe? Does your draft inducer motor run before and after the gas has ignited? Check and confirm these 3 things first. Good Luck!
Replacing the board, flame sensor, and pressure switch, and cleaning out the induction motor was definitely a good start. Other things to check would be a blocked or restricted flue pipe, I have ran into a few bird nest before!, and you also want to check or replace the hose that runs from the inducer to the pressure switch if you haven't already. To be honest, most of the time I clear out the nipple on the inducer where the hose goes with a small piece of wire and it works. The last thing I would suggest is making sure the new pressure switch is rated for what you need. Alot of the revisions on furnaces actually call for less than the original pressure just for this problem. Hope this helps and good luck!
It sounds to me like your draft motor is probably shuttimg off on thermal overload. They will get to hot and shut down until the motor cools down then run again.But by that time it's caused other trouble so I think you need to replace the motor first and then see what other problems it has caused.I hope this helps you and thanks.
The unit senses a failure to ignite, so it goes into safety mode keeping the blower running to prevent overheating and fires. And keeping the inducer motor running to prevent the same, as well as raw gas build up inside the unit.
The newer systems are "smarter" and can detect more specific problems and failures. The older ones simply know that the thing didn't light, so they bring on the fans for safety.
I have an Amana High Efficiency furnace that I purchased 5 years ago this past October (2009). My furnace started making a horrible noise last night and then stopped working. The repair person, told me my draft inducer motor needed replaced, and showed me where the plastic fan blade inside of the inducer was "chewed up." Of course my first question is, "How can a 5 year old furnace need such a costly repair already?" The only answer I received is that it will cost me close to $500.00 to have the situation remedied (service call, parts, labor). I started looking around on the internet today, and discovered that high efficiency furnace inducer motors are usually encased in plastic and the motor fan blades are made of plastic rather than metal like the lower efficiency models. Turns out that these plastic blades over time can't withstand the high heat generated and in time (they estimate 3-4 years) break. The damage to the blades causes an imbalance in the way they spin, which in turn, generates the resulting problem of a damaged draft inducer motor. Appears this is a design flaw. Yeah! I'll say. I spent $3100.00 for a brand new furnace and 5 years later I'm paying another $500.00 and apparently can look forward to doing the same in 3-5 more years! Maybe this answers in part your question?
If it is calling for heat the draft inducer it is the first device energized, the pressure switch will want to be proved and then the ignitor will glow and the gas valve will energize and the sensor will prove the flame and the heat is on.
If one of the above is not in the right time and place the rest will not work. About the fan it is either a shorted control wire for the fan or the limit switch (the high temperature limit) is made or bad.
If that is not the case the the thermostat has a switch in the back between the gas fired or electric. That will determine if the fan should be on every call for heat.