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Heath, HVAC Technician
Category: HVAC
Satisfied Customers: 1034
Experience:  11 yrs. comm.resid. service, Type III Cert.
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Bryant Plus 90 gas furnace will not fire up.

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My Bryant Plus 90 gas furnace will not fire up. The blower motor is running but the fire box is not igniting. I remember from last year, a tech cleared the condensation drain and made adjustments to the flame. I'm starting the heater for the first time and the fire box will not ignite.

Hello, it will be my pleasure to assist you. First thing to do is go to the furnace and look in the small peep hole in the lower blower door and see if there is an LED light that is flashing a certain number of blinks. Record that number and look for a diagnostic chart on the inside of the blower door or the upper side panel of the furnace. If there is no flash code present, you can try resetting the power to the furnace and see if it will fire up.

Customer: Okay, if you can give me a few minutes, I will check. If there is no flashing code, what is the best way to reset the furnace? I already tripped the circuit breaker and reset. There were no changes.

Heath: Okay, let me know if you get the flash code from the LED.

Customer: The flash code was 33 according to the chart on the door. Three quick flashes followed by three slow flashes says it was a flame rollout fault.

Heath: Okay, the flame rollout is near the burner section of the furnace usually there is more than one locate the rollout and in the center there is a red reset button that you will have to press in order to reset the rollout switch. Press this red button firmly and the switch will reset.

Customer: Here's what I've done so far. I inspected the igniter, the rod seemed to have a slight carbon buildup on it. I cleaned the rod and replaced it. I leveled off the condensate drain pipes (they had some water in them. I blew through the two lines connected to the condensate box until it was clear. I put in a new air filter. I inspected the fire box as best as I could. The unit under the house and is partially blocked by a floor support. The box seems relatively clear. I don't see a carbon buildup or much rust. I tried to reset the flame rollout sensor, but the reset switch doesn't seem right. It feels loose and does not have a definite click like to reset. After all of this and turning the unit back on, the heavy duty blower came on and a code of 12 flashed on the LED. After about a minute, the heavy duty blower stopped and the inducer motor came on for about 30 seconds and stopped. The flame came on in the fire box and the LED stayed on indicating everything was "Okay". The unit ran for most of the night and quit producing heat. The heavy duty motor stayed on blowing out cold air. I had to shut the power off to the unit. Tried the same procedures today and the unit started up again. There was a little condensation to clear from the line and I cleaned the igniter again, but it looked really clean. I'm thinking that the condensation box does not drain well and caused the unit to shut down or the rollout sensor is bad. The problems started with this blowing only cold air. The service techs let the water drain under the house and adjusted the flames because he said it was rolling out. Do you think I should replace the condensate trap and the rollout sensor?
Heath: Replace the rollout sensor, that's what seems to be tripping the furnace. To verify this - undo the wires and use an unbent paperclip to jump the wires together thus taking the rollout out of the equation. If the unit stays running then the rollout is the problem - if not - then it's the condensate trap.
Customer: I followed the advice of the rollout switch and the condensate trap and the unit still kicks off after a few hours. I was able to get a hold of the original contractor that installed the unit and they explained it was the heat exchange and that it was still under warranty. They came out to fix it yesterday, but still needed to replace a nozzle on the gas injector so they said. Hopefully, all will be alright by tomorrow. Thanks for the help because I learned a few things about the maintenance of the furnace.
Heath: You are very welcome have a wonderful day!
Customer: I appreciate your help. Thanks again!
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