Carrier 58CTA/CTX problems


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Old 09-07-09, 03:18 PM
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Smile Carrier 58CTA/CTX problems

I have a Carrier 58cta furnace and it won't put out any heat. It shuts down after about a minute. The burners light for about 30 seconds and then stop. the heater is about 2 years old and was working fine until this happened. It has a code 31 on the blinking led. Any ideas would be appreciated. Thanks
 
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Old 09-08-09, 09:07 AM
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Often when a furnace runs but goes out at some time frame after say about 4 seconds, it probably is not the flame sensor, and more likely to be pressure switch related. That is the (vacuum diaphram switch that proves that combustion air can move fresh air through the furnace and get rid of spent gases.

Related to that would be actual causes like, you could have a venting blockage, slow fan, or even condensate water that is hanging up in the furnace.

If you have a voltmeter and are willing to test stuff, we can tell you how.
 
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Old 09-08-09, 10:10 PM
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voltmeter

Thanks for the reply,

I have a voltmeter and can test. It would be nice if i can test the pressure switch because it is pretty expensive.

Thanks
 
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Old 09-10-09, 04:47 PM
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Thanks for the reply,

I have a voltmeter and can test. It would be nice if i can test the pressure switch because it is pretty expensive.

Thanks
 
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Old 09-11-09, 06:22 PM
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When the furnace starts up, you have 24 volts ac incoming to the pressure switch. The pressure switch is supposed to close, and stay closed during the heating cycle, if everything is fine in the furnace venting and drafting dept.. And then that means if you test the outgoing pressure switch wire to ground, it to should also be and remain at 24 volts. If it goes away on you, and then the flame immediately thereafter shuts off, you have one of those problems I listed in my prior post. It could be any one of those problems, or the pressure switch itself could be the cause if all the other things check out fine. You need to check out each thing.

If you do this, I can yet assist further in trying to hone in on the problem.

If the outgoing pressure switch's 24vac outgoing current goes away, while the incoming 24cvac remains,[But if both go out, it is some other cause instead, related to the electrical system!] then this means that your pressure switch points are good, most likely, otherwise the fire would have never even tried to come on. But the problem could still be with the drafting or venting or condensation backup, or the pressure switch itself in regard to not the switch but with the spring tension and diaphram if maybe there is a pinhole leak in it.

More in regard to this involves sucking on the vacuum tube and pincing it off to see if the diaphram may have a leak. And the best test is with a manometer tool that indicates water water column(W.C.) in inches - which basically is another form of a psi test - whose height will be relative to the applied vaccum.

If the drafting, venting and condensate problems have been ruled out, and the 24vac only disappears on the outgoing side of the switch, only then could you reasonably guess it is the pressure switch itself. But it is still hard to conclusively know just what the draw through the furnace is capable of, and that there is no internal plugging of the furnace.

Furnace men are at a real advantage here because they will carry these in their truck as even spares, and can quickly throw one in and try it and see.
 

Last edited by ecman51; 09-11-09 at 07:08 PM.
 

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