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Re: armstrong air tech 91 furnace problem
Sounds like the flue is plugged, I had same problem and opened up the draft fan and there was a dead bird restricting the flue. Furnace will never light if the pressure switch never closes as you have found out. Also has anyone moved the switch some are position sensitive meaning have to be in same position factory set the switch. I had one like that also switch was little crooked so I straighten it up and walla worked.
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Depends on the system,if it has 2 wire switch it can be bypassed,but only 1 time for each heating cycle if the system is using i pc board to operate the furnace,sometimes you can take the hose off and lightly suck and blow on it if the switch is stuck,but should have a pro check it,could be a blocked flue pipe or other dangerous problem,and could be a bad switch,did heating and cooling for 30 years
Hello, this indicates a open limit switch. A limit l switch will open when the temp in the heat exchanger gets too high and this switch shuts the Furnace down for safety. Usuaully a dirty filter, weak blower motor, dirty blower wheel will cause a limit switch to open.
this indicates fault 33, on inside of access panel will tell you faulty switch. i believe off top of my head is pressure switch open, this a safety switch to verify that inducer fan is working, several things besides a failed part can cuase this, there is a rubber hose going from the inducer fan houseing to the safety pressure switch, remove hose from fan housing and run a small stick ,wire or torch tip cleaner, down the acces port, calcium builds up inside the port and blocks the sampling of pressure, reassemble and try it, if this works add it to yearly maintenance could need new switch or inducer fan motor, these need to be replaced by a tech, also birds can block flue pipe
Read one LED flash that stays on continuously to mean your furnace has no signal coming from the thermostat and will not operate. Turn the power off and check the thermostat for improper settings or connections.
Interpret one LED flash that blinks on and off to mean your furnace has locked out because it could not ignite after three tries, and must be reset. Interrupt power to your furnace for 20 seconds or lower the thermostat so your furnace does not try to heat, then reset the thermostat to the previous setting. After one hour of lockout, your furnace will automatically reset itself and try to operate as usual.
Decipher two LED flashes to mean the draft blower is not working, or your furnace has a short in the pressure switch circuit. Turn off the furnace power and repair a short or replace the pressure switch.
Read three LED flashes to mean your furnace has an open pressure switch circuit or it has an induced draft blower operating. Check the pressure switch hose of your furnace for blocks or an improper connection. Also, look for blockages in the flue, and tighten any loose wiring.
Translate four LED flashes to mean your furnace has a primary limit circuit open, possibly from loose wiring or blocked filters. Check and clean filters, tighten wiring and check the flue for blockages.
Interpret five LED flashes to mean your Goodman furnace senses a flame without a call for heat. This could be from a gas valve closing slowly or a burner flame lingering.
Read seven LED flashes as a warning of a low flame sense microamp signal. This could happen with a coated flame sensor or a lazy flame from poor gas pressure. Turn off the power and adjust the gas pressure according to the information on the rating plate.
See eight LED flashes as meaning an igniter circuit problem due to a bad igniter or an igniter connected improperly. Replace the bad igniter or check the ground wiring, making necessary corrections.
Decipher nine LED flashes to mean the high-stage pressure switch circuit will not close during a high-stage-induced draft blower operation. Your furnace may have a pinched or blocked pressure switch hose, a blocked flue or loose wiring.
Read continuous flashing on the LED to mean your furnace has a reversed polarity of 115 volts. Turn off the power and correct the wiring polarity after reviewing the wiring diagram.
On the limit switch that protects your unit when it gets to hot the number one reason is dirty filter.
The pressure switch is located in the upper side of cabinet has a rubber hose connected to it. They very rarely go out though. So find your vent fan the first fan that comes on and follow the rubber hose to the switch.
Downstream of your fan discharge there is a little plastic assy. most likely that will have a pickup tube and a piece of vinyl or latex tubing attached. First check to make sure that the pick up tube and/or tubing does not have a restriction. If it is clean use an ohm meter to read resistance across the switch to verify it is operating.
These furnaces goes thru 4--steps for complete run time.... step-1, the small draft inducer blower motor blows and prove thru the small air tube that sucks a switch close to tell the circuit board to go to step-2......the glow plug glows for 15 seconds and step 3 the gas valve opens and dump gas in the venturi tubes and lights off the glow plug and proves thru a flame sensor (pin with 1 electrical wire connection) on the last venturi tube which tells the circuit board to go to the last step 4--, to turn on the main blower fan after 90 seconds!. Where ever it stops at then thats where your problem is!
If you know where the high limit switch is you can always cut the two wires and wire them together causing the limit to close. But what you have to watch out for is why the high limit is not closing. That means in your return air either you have a dirty return air duct, dirty filter, or you don't have all your registors open to allow the heat to escape the heat exchanger. Just watch over riding the system. The high limit switch should either be on or behind the blower, in the middle of the system right under the heat exchanger. any other questions about hvac just ask.