Carrier WeatherMaker 9200 won't light

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  #1  
Old 01-20-08, 06:57 AM
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Carrier WeatherMaker 9200 won't light

Hi -

I have a Carrier Weathermaker 9200 that will not ignite consistently.

It is set up upside down...I think this is called "downflow"? The cold air comes in through the top, the hot air goes out in the floor as my hot air registers are in the floor.

Anyway, the furnace seems to work just fine usually. Every so often, though, like every couple of weeks, the blower will start but the furnace will not ignite. After awhile, the blower will stop.

If I go in and perform the reset procedure (turn off thermostat, turn off power, turn off gas switch, wait 5 minutes, turn on gas switch, turn on power, turn on thermostat) I can usually coax it to ignite and run normally. It will be fine for a couple of weeks, then it will stop igniting and I'll have to do the reset again.

There is no LED code when it doesn't ignite...the only LED I can see is always solid red, which according to the code list on the back of the access panel, everything is OK.

I don't mind calling for service, I am just wondering if a) this is something I might be able to fix myself, b) if anyone can tell me the likely problem so that I have some advance knowledge before a tech comes out and tries to give me a story about what is wrong.

I'm pretty handy, though I am a complete rookie at HVAC. But I have fixed/improved/corrected just about everything else in a house before, including plumbing and minor electrical and fix my own appliances (washer/dryer/stove etc).

Any ideas or suggestions? Thanks in advance.
 
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  #2  
Old 01-20-08, 08:41 AM
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Originally Posted by johnzilla View Post
Hi -

I have a Carrier Weathermaker 9200 that will not ignite consistently.

Every so often, though, like every couple of weeks, the blower will start but the furnace will not ignite. After awhile, the blower will stop.

If I go in and perform the reset procedure (turn off thermostat, turn off power, turn off gas switch, wait 5 minutes, turn on gas switch, turn on power, turn on thermostat) I can usually coax it to ignite and run normally. It will be fine for a couple of weeks, then it will stop igniting and I'll have to do the reset again.

There is no LED code when it doesn't ignite...the only LED I can see is always solid red, which according to the code list on the back of the access panel, everything is OK.
Please note that the board in this furnace only retains the last fault code (the last failure that happened in your furnace), for a period of 48 hours OR until power is interrupted

Yep! your LED is solid red; but likely b/c of the routine reset procedure you mention above, you're unknowingly erasing the code.

Next time the problem happens, do not cut power, go to the furnace, remove ONLY the "main furnace door", not the blower door (that would erase the code too) and thru the sight glass check for the fault-status of the LED

Do you have handy the chart of code-faults for your unit?
 
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Old 01-20-08, 08:49 AM
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Hi -

Thanks for the reply.

The furnace won't light at all now. It ran off and on for a couple of hours this morning and got the house temp up to 66 but now it won't light at all.

The LED is blinking now, too. The code is 31. According to the panel, 31 means:

"pressure draft safeguard auxiliary limit or blocked vent shut off switch did not close or reopened"

I've googled around and found some other threads saying to check the vent pipes as well. All are tight, and they are covered outside on the so I don't think anything dropped in there but I guess they could be blocked by something like a nest.

Thanks again for the replies.
 
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Old 01-20-08, 09:20 AM
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o.k., the burners won't light up...but...did the induction blower at least kicked-ON?

Pls report what does the unit do...i.e.: when t'stat calls for heat the induction blower starts running, the hot surface ignitor starts turning red, I hear a click from the gas valve, etc.

NOW YES, you need to turn power (115V) OFF just so the furnace resets its codes, else, it won't turn ON at all for the next 3 hours.

What do you mean by "The vent pipes are covered outside"?????
After the induction blower kincks-ON you'ge got to run outside and put your hand near the plastic pipes...one should be blowing air, the other sucking...if such is not the case, one (or both) are blocked
 
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Old 01-20-08, 09:37 AM
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Hi -

Thanks for the reply.

My house is small, so I can hear the furnace quite clearly and am very familiar with the sounds it makes when it is running correctly.

Right now, the thermostat calls for heat. The blower motor starts running. The igniter (it is electric/electronic) does NOT come on, and looking into the burner chamber (there's a little round window where you can watch the flames when it is running correctly) I see no flames. After awhile, the blower motor stops, and the LED is blinking the 31.

When it runs normally, I can hear the blower start, and a little while later (maybe 10-20 seconds) I will hear the gas start and the igniter click. About 10-20 seconds after that, it seems to "shift gears" and get a little louder and warm air comes out of the register. That's the normal way.

Right now, I only get the first part...the blower comes on and thats it. I don't hear or see anything else. No flames, nothing, just the blower motor.

I can not check the vents...they are up on the roof. By "covered up" I mean they have covers to stop squirrels/birds/etc from getting in there, or from pine cones or whatever from dropping in. They are not "covered up" as in "blocked" as far as I know. Again, everything was running just fine last night, it is only this morning that I am having an issue. The only way I could verify airflow on the vent pipes would be to cut them (they are PVC) and visually check. I'd rather not do that if I don't have to.

Thanks for the replies.
 
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Old 01-20-08, 09:58 AM
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O.K.
The ignitor appears to be the root of the problem.
The ignitor is by the burners.

There should be a plug with 1 black and 1 white wire feeding the Hot Surface Ignitor. I believe it is bad. How do you test it?

Disconnect the plug connected to the ignitor and see if you can direcly feed the 2 terminals of the ignitor with 120V. You'll need to use a 120V x-cord with a plug on one end and alligator clips on the other, just so you can clip on the two terminals on the ignitor. If it does not glow, it is bad. From what you describe, this should be the problem

Good luck...I have to run.
 
  #7  
Old 01-21-08, 05:14 AM
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Hi -

Thanks for the replies.

Just as a reference for anyone else having the same sorts of problem, my problem turned out to be a flaky pressure switch. I cleaned it up and reseated the connections and it is running fine now...but if it flakes out again I will replace the switch.
 
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Old 01-21-08, 05:22 AM
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Thanks for the feedback...
 
  #9  
Old 12-21-08, 09:48 PM
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Originally Posted by johnzilla View Post
Hi -

Thanks for the replies.

Just as a reference for anyone else having the same sorts of problem, my problem turned out to be a flaky pressure switch. I cleaned it up and reseated the connections and it is running fine now...but if it flakes out again I will replace the switch.
Thanks for the info. I tried what you said and it solved my problem. Thanks again....
 
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