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I have a Bryant plus 90 gas furnace. The furnace is just turning out cool air, and the fan stats on constantly. Led code 33 blinks for 3 minutes then switches to code 13 which is the flame rollout lockout code. Removed air filter, removed condensation drain hose, made sure no vents were blocked, and the exhaust vent is cleared. Any ideas on how to get this thing running correctly again? Can't really find a manual reset switch and if I did, it didn't effect anything.. . help
I am not an HVAC guy, but I have worked on a number of high efficiency furnaces. If you turn the power off to the furnace and then turn it back on it should restart its cycle.
The cycle goes something like this: The small ejector fan will immediately start if the system is calling for heat. This small fan makes sure that the exhaust system is working correctly and it runs for a time- about a minute depending on furnace. There is a differential switch(has small hoses attached to it) that senses that the ejector air fan is working. The control board starts its time from this time it sees this is okay, which it probably is from you have said. Then the ignition cycle starts. This is the place where I think you are having issues and they could be several. If you stand by the furnace when it is powered on again you will hear the small fan start- a little later you will probably hear a click. This is the control module turning on the igniter. Often this igniter gets burned out much like a light bulb does. I don't know on the Bryant how visible the igniter is, but it is located near the front of the heating tube(exchanger) and generally visible from the front. If it glows hot you can generally see it- I am assuming you won't see this due to a common problem will all high efficiency furnaces and that is this igniter has burned out. If the igniter does work, there is a flame sensor with a wire attached to it that goes back to the control board.
The control board tells the igniter to turn on. It should get hot. After it is hot you should hear the gas valve click on and the igniter should light the gas. If the flame sensor does not see a flame in a certain amount of time, the controller will shut of the gas valve as a safety feature. In some controls this gives you a lock out failure.
Unless there is something a little different about this machine, this is the normal reason for no heat. You can shut the furnace off electrically and remove the ignitor- generally held by some kind of clip or clip with screw. Be careful not to touch the heating portion of the igniter. The oils from your skin will cause it to burn out prematurely. Inspect it once you get out. You will generally find a very small crack
In the igniter material. This can be checked also with an ohmmeter if you get on the leads going to the igniter. Continuity generally means it's good unless really high resistance. If the igniter works and gets hot then some times the flame sensor goes bad or is not close enough to the flame to sense the flame. The pilot flame which the initial gas valve position for the ignition cycle lets enough gas to light the furnace and for the flame sensor to see. If the sensor has been bumped out of the flame it probably won't work. Most sensors in home heating systems need to be in the flame.
I worked with huge gas furnaces in industry and they actually have an IR detector for sensing the flame, but I think the cost of the technology has kept it out of the heating furnaces like yours. I could expound a little more, but let's get past this part first. I think you will find a bad igniter or some associated device or wire. Gas valves do go bad, flame sensors do go bad, wiring sometimes gets melted to the frame on the flame sensor and sometimes a Control board goes bad. I would look at all alternatives before going to the control board. A new igniter sells for around $40 I think- depending on the igniter and where you buy it. Some HVAC have igniters that they prefer and sometimes substitute them for ones in furnaces that are compatible because they found better life cycle. I keep a spare one in my garage for my furnace- just replaced it in February. Good luck, hope I kept it simple enough for you.
Replaced the limit switch, replaced the ignitor... still no different from before. Before the fan even comes on the led is flashing code 33, fan comes on... and that's it, no click, nothing else.. . After 3 minutes the code switches to a code 13 just like before
The codes shoud be explained on the back side of the blower compartment door, look there. ERROR CODE 33 - Bryant Furnace constantly restarts - YouTube
Zingle,Quote:
Originally Posted by zingle
If nothing happens I need to know. Does the small blower start on a power up cycle? I looked at the video response and I could be wrong, but I think you are looking at a little different issue. The little fan and its corresponding pressure switch are fail safe devices intended to make sure that there is plenty of exhaust air in the furnace. The little fan blows air out the exhaust which creates a small differential pressure in the fire box. The pressure switch has a tube that compares that pressure to the atmospheric pressure to determine that the exhaust fan is working. If the tube is plugged then the switch won't work. Sometimes the pressure switch goes bad too. Before I go any further though can you enlighten me on what part of the sequence works? Does the small exhaust fan turn on first? If the small fan doesn't turn on the rest of the cycle will not proceed. I am glad to help at no cost. Doing this as just a service, so I will work with you if you can help me understand a few things. Get back to me?
I will try to watch for your reply.
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