Bryant 395CAV furnace: error codes 34 & 14


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Old 11-08-16, 02:28 PM
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Bryant 395CAV furnace: error codes 34 & 14

I have a Bryant 395CAV furnace.

When I first turned it on this season, it wouldn't start. I typically have to clean the flame sensor every year, so I did that. Filter was replaced. It ran fine for a couple weeks.

After a few days in a row of warmer weather where the furnace wasn't needed, I've started having trouble with it again. I get Error Code 34 (ignition proving failure) and then Error Code 14 (ignition lockout).

Sequence of events is -

Turn heat on at thermostat
Inducer motor kicks in
Ignitor starts glowing
Gas kicks on
Flame come on for a few minutes
Flame goes out (Error Code 34 happens here)
Cycles through a few times trying to re-light - I don't believe it's opening the gas at this - I don't hear a hiss or smell anything - ignitor is coming on as it should
After a few attempts at relighting, furnace shuts down with Error Code 14

I tried cleaning the flame sensor again, and then replacing it.

I've removed the hose from the pressure switch and attempted to clean the ports. The hose itself was clean, and the ports looked clean, but I poked around with a paper clip anyway.

I noticed that when the burner and blower covers are off, the furnace will operate normally and the flame will run until the house warms up to temp and then the cycle will end normally with no error.

If I have just the burner cover off, it doesn't help.

Tried once with just the blower cover off. The blower cover covers part of the burner area. It seemed to create a sort of backdraft in that the flame came out through the back of the burners for a second and then the furnace shut off.

Is there something I'm missing, or is it just time to give up and call someone in?
 
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Old 11-08-16, 03:03 PM
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Welcome to the forums.

You may have a flue problem with your furnace if it runs with the covers off. You also need to make sure ALL the burners light. One may be dirty keeping the flame from carrying over properly. A flame sensor problem will cause the burner to shut off in a few seconds after lighting.... not several minutes.

Here's the link to your manual. The last two-three pages there are diagnostics you can follow based on the trouble code 34.

hvac partners/docs/1009/Public/0E/SP04-54.pdf
 

Last edited by PJmax; 11-08-16 at 08:47 PM. Reason: typos
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Old 11-08-16, 05:45 PM
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PJ Max provide good advice. Unfortunately, your situation is a little ambiguous, which makes diagnosis more difficult.

As PJ Max suggests, that the furnace works OK when the cover is off the burner suggests some kind of defect in the ventilation of the burner system/vent.

Usually that kind of defect would cause the pressure switch to open, which would give you a different error code than what you get.

The idea that one burner isn't lighting should be checked out.

You probably need to examine the ignition sequence several, perhaps many times. You first need to get familiar with what happens when the furnace lights normally, and then notice any changes when it doesn't light properly, or shuts off.
 
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Old 11-09-16, 06:24 AM
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Thank you PJMax and Seattle Pioneer.

All burners are lighting. I've watched it many times now.

When I got home last night, I discovered the furnace had worked well enough all day to keep the house at the set temp on thermostat (70 degrees). I waited a bit, watched it cycle on/off a few more times successfully, and decided to not touch the furnace last night. It continued throughout the night and into this morning, cycling on and off and keeping the house at temp.

The furnace vents through the roof, and I'm not a big fan of climbing onto the roof in the dark, so I didn't check it last night. I tried to look for some sort of access to check the vent from the inside without tearing the ductwork apart or messing with the now at least somewhat operational furnace. I didn't find any access, but I did find...

Holes. Several holes of various sizes in the vent duct. It was not good. I ran out and bought some foil tape and patched the holes until I can replace the duct. I feel comfortable the holes are patched and things are operating safely as far as exhaust fumes are concerned, but I plan on stopping for a carbon monoxide detector on the way home today. I regret not thinking of that when I got the foil tape last night.

But anyway.... that long story brings me to this question - could the holes in the ductwork have been interfering with the exhaust and causing my furnace issue? I don't know, but I'm wondering if they could have prevented the updraft and caused an issue similar to the vent being blocked?
 
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Old 11-09-16, 10:44 AM
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You found holes in the ductwork or the exhaust flue line ?

Holes in the ductwork won't effect the burner. That is treated air and not harmful to breath.
Holes in the exhaust flue are disastrous.
 
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Old 11-09-16, 10:53 AM
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In the exhaust flue line.
 
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Old 11-10-16, 09:35 AM
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When I got home from work last night, I had more issues. The furnace stopped working well enough to even keep the house at 65. It's a bit chilly. It was 62 in the house when I left for work. I'm hoping for lots of direct sunlight today.

I checked the flue area of the furnace. There was some dirt build up, but didn't look like enough to block the airflow. I vacuumed it out. I'm still too chicken to climb onto the roof in the dark to check the opening there.

I'm still getting a flame for a few minutes and then the flame goes out and I get an error 34 and after a few attempts to relight the furnace, I get an error 14. I tried several times last night to keep it going with both covers off, but it was still shutting down after a few minutes, so I seem to have lost the use of that trick. I had one instance where it ran for 7 minutes until it shut off for reaching temp. I bumped the thermostat up until it clicked back on. It then shut off again after a few minutes and wouldn't relight.

Something else started happening last night that seemed to be a new wrinkle. Previously, if it shut off and I cycled power, it'd do the light and burn for a few minutes, then shut off cycle. Last night, cycling the power didn't seem to be enough to get it to relight. I had to turn it off at the thermostat, too. So my sequence of events was to turn the power off at the cutoff switch, run upstairs and turn off the thermostat and turn it all the way down, go downstairs and turn the power back on, go back upstairs turn on at the thermostat, and turn the temp setting until the furnace kicked on. Then I'd get my few minutes of flame before the 34/14 errors struck again.
 
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Old 11-10-16, 10:05 AM
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You need to have the flue line checked out. There should NOT be any holes in it. If the flue is rusted out the rust may have fallen into the furnace.
 
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Old 11-10-16, 10:59 AM
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If there are holes in the flue then your going to have bigger problems then being cold, like being dead from carbon monoxide poisoning. If the flue is rotten then tape isn't the fix. The flue must be replaced.
Can you please post pictures of the furnace as well as the holes you mentioned.
 
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Old 11-10-16, 08:38 PM
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Had a guy come look at the furnace. He said there's a crack in the heat exchanger.

Does that make sense with the symptoms? Or just something likely to be wrong but unrelated?

I hate to be the skeptical sort, but he did seem to go pretty quickly to trying to sell me a new furnace.
 
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Old 11-10-16, 08:58 PM
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Did he observe the flames after the blower started ?
If the flames move when the blower starts.... the exchanger is cracked.
 
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Old 11-10-16, 09:32 PM
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There are smoke bombs that you put into your furnace and if the heat exchanger has a crack the smoke will come up through the registers. That means your combustion chamber which is where your fire takes place is leaking into your house and it's obviously suppose to be separate. This is very dangerous. I would think you would have noticed something was wrong, either a little smell or possibly a little soot although you do have gas. How did he arrive at his decision about the crack.
 
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Old 11-10-16, 09:44 PM
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When I worked as a repairman for a gas utility, I recall being called out to a customer's home where the repairman had just diagnosed a cracked eat exchanger.

I looked at the heat exchanger and saw nothing wrong, so I asked the guy here this crack was. He looked again and said "Oh, I guess that was a spot of dirt."

Dang! No commission for HIM!


The problems you have could easily be due to a cracked heat exchanger. Or to something else.

Unfortunately, it's all too easy for people to see a crack where there isn't one.

When I diagnosed cracked heat exchangers, I SHOWED people the crack when I could. That wasn't always possible.



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Old 11-11-16, 07:27 AM
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I think he kind of guessed from the symptoms he saw, but he did tear it apart and look inside with a camera. He didn't show me the crack, but if I stop being paranoid for a few seconds it does seem like he made a legitimate effort coming to the conclusion.
 
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Old 11-12-16, 12:31 PM
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Good. There are certainly plenty of cracked heat exchangers out there, and honest and competent repairman too. Just not enough of THEM!


After you have the furnace replaced, you can examine the heat exchangers easily for holes and cracks. If you don;t see any, the repair company that made the observation that they were cracked ought to be willing to come back to show you the cracks they saw.

If they aren't there, you have a small claims court case that could be made for a poor diagnosis or perhaps for fraud.
 
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Old 11-12-16, 03:05 PM
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So the story continues...

I don't own the house, so I'm not the one buying a new furnace. I was just hoping to fix it myself if it was something relatively cheap and simple, and the landlord can be kind of hard to get a hold of, like he is now.

I did manage to get through to the landlord and told him what the furnace guy told me. He sent out his maintenance guy yesterday. The maintenance guy didn't agree that the heat exchanger was the problem. He made comments similar to what PJMax said.... the flame wasn't moving and was nice and blue. He decided to replace the flue vent and a couple of switches. He said he'd have to go get the parts and come back today.

I've been sitting here all day in the cold waiting for this guy to come back. He told me 45 minutes ago he'd be here in 15 minutes.
 
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Old 11-12-16, 03:32 PM
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Post some pictures of the furnace and associated vent
 
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Old 11-13-16, 11:05 AM
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Maintenance guy came in. Replaced the flue pipe. Replaced a couple of switches - a small roundish one near the vent at the top and a rectangular one along the back of the burner area.

Furnace fired up. Ran a few minutes. Maintenance guy took off like a guy on unpaid overtime. I waited about 20 more minutes. Furnace was working well. I took off to do some things.

Came back a few hours later. The thermostat was set at 75. The temperature in the house was 68. The furnace was in ignition lockout. I thought maybe it had overheated due to starting out at 55 in the house. I reset the furnace and went to bed.

I woke up a couple hours later and the furnace had shut off again and the temperature was dropping. Kept doing this throughout the night. I called the maintenance guy this morning and am waiting for him to show up.

I tried to make a video of it going through its cycle, but now it won't even light. The ignitor glows, I hear a click, can't tell whether I'm hearing gas or not. I think I might be. Then the ignitor shuts off. It does this 4 times before going to ignition lockout.
 
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Old 11-13-16, 11:26 AM
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Please post some pictures of the furnace and vent
 
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Old 11-13-16, 05:50 PM
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The maintenance guy lacks the equipment or training to decide whether the heat exchanger is cracked.

A REPAIRMAN might use a match on a stick to light the main burner gas when /if it turns on. Of course, if you don't due that properly, you can singe your eyebrows when the gas lights off!

The heat exchanger isn't the problem with this symptom. Either the gas isn't turning on because the circuit board is bad, because the electric gas valve is bad or the hot surface ignitor isn't getting hot enough to light the gas.

When I was a repairman, when I found an unsafe condition such as a cracked heat exchanger, I disconnected the furnace so that it couldn't be used until repaired or replaced.
Someone needs to accurately diagnose the reason why there is no ignition.

Speaking as a landlord myself, it's really a mistake for a tenant to get involved in this kind of problem in my opinion. Build a fire under the landlord to have that repairman come back and find out why you have no gas ignition.

I'd get a copy of the cracked heat exchanger warning ---- them owner is VERY unwise not to take that seriously.
 
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Old 11-15-16, 07:25 PM
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I have heat.

Gas valve was replaced. Furnace has been working fine since.
 
 

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