Furnace error codes

[theoldwizard1]

So my daughter is a recent single mother, working a full time job from home and taking care of 4 kids (2 teenagers, 2 pre-teen). Obviously she has a lot on her plate.

Last week the furnace would not start (igniter comes on, no gas). Code 34, "IGNITION PROVING FAILURE". I cleaned the flame sensor (silly, because there never was a flame) and replaced the igniter. No joy. 5 days later (weekend in the middle) the furnace guy shows up. Cleans the sensor, check the igniter and of course get the same error code.

After discussing it with his boss on the phone, they decide it must be the control board. Made dash to obtain one before warehouses close, swap in, SAME ERROR CODE ! Boss shows up. Lot's of head scratching. They finally decide it is the gas valve. New valve the next day and success ! For 2 days !

Now she is getting an intermittent Code 43 "PRESSURE SWITCH CALIBRATION FAULT". Could one of the guys bumped/moved something (intake air manifold/shield?). My gut says it is NOT the pressure switches !

This is a high efficiency furnace where outside air is brought in for combustion. There is a gap between the shield/manifold and the burner where I can see the flame. Should this be sealed ?

 

[steves_001]

I don't recall the exact codes I ran across on this one but what happened was mud wasps created a nest in the intake and stopped the combustion fan from running. Usually it has a spinner on it to see but check that and also verify the intake is clear. With no pressure, the valve will not send gas.

 

[fitter30]

Normally 95% furnaces burner compartment is sealed. Have a brand and model #?

 

[Bert_]

I wouldn't put much faith in their diagnostic skills. A bad gas valve is pretty easy to troubleshoot, no gas, check if the valve is getting power...

I've not heard of a pressure switch "calibration" code. Best to check with the manufacturer what would set that code.

Normally they just say pressure switch stuck open or closed

 

[PBCampbell]

Yes, need some information about the furnace and your HVAC people stink at troubleshooting, throwing parts in hoping something solves it isn't very prudent. You make no mention if the "induction" fan and its sensor was checked for proper operation.

 

[theoldwizard1]

You make no mention if the "induction" fan and its sensor was checked for proper operation.

The igniter will NOT come on if those are not working !

Not certain if these is the "root cause" but, the HVAC company called my daughter today and said there was a safety recall on the heat exchanger. No charge for parts or labor. Obviously, it will take some time for the part to arrive. Flipping the main power switch gets at least one heat cycle.

 

[4x4Pete]

Probably condensate drain blockage

 

[Fav Onefour]

The igniter will NOT come on if those are not working !

Not certain if these is the "root cause" but, the HVAC company called my daughter today and said there was a safety recall on the heat exchanger. No charge for parts or labor. Obviously, it will take some time for the part to arrive. Flipping the main power switch gets at least one heat cycle.

When you say one heat cycle, do you mean it is satisfying the stat?
I have seen pressure switches that like to stick. I have one version that I just buy two at a time.
Those switches will eventually open again, or the units can be reset and run a cycle.

It sounds like that unit is giving you multiple issues. That seems problematic. I wonder if there is some other underlying cause for the multiple errors?

BTW, did I miss something with the codes? I didn't see anything about a brand or model line. Some of these goofy issues are inherent to particular models.
I'd be surprised if the heat exchanger is creating multiple error codes. Speaking to the recall and action, I'd guess it's one of four companies that used the same basic exchangers that had plastic components. I'd check to see if the whole repair stream should be covered under that recall. The units should have received an extended warranty.

 

[dchawk81]

Not trying to troll but do furnaces have OBD ports like a car these days? The idea of error codes on a furnace blows mind.

 

[Wrench97]

Not trying to troll but do furnaces have OBD ports like a car these days? The idea of error codes on a furnace blows mind.

No a LED light that blinks.

 

[dchawk81]

No a LED light that blinks.

OBD1 then?

 

[Wrench97]

OBD1 then?

Close they automatically blink when there is a fault.

 

[theoldwizard1]

When you say one heat cycle, do you mean it is satisfying the stat?

Yes, it satisfied the thermostat. Next request is a **** shoot.

I have seen pressure switches that like to stick. I have one version that I just buy two at a time.
Those switches will eventually open again, or the units can be reset and run a cycle.

One of the error codes said something about pressure sensors out of calibration (?)

It sounds like that unit is giving you multiple issues. That seems problematic. I wonder if there is some other underlying cause for the multiple errors?

I feel the same way ! Especially after the first technician BROKE THE IGNITER (why do you have to remove an igniter to test it?) after I told him/showed him that it had been replaced and it was clearly operating (getting white hot) ! Definitely this guy was from the "B team" !

BTW, did I miss something with the codes? I didn't see anything about a brand or model line

Bryant/Carrier, although my (very limited experience) says that codes are (mostly) universal.

 

[cannuck]

Yes, need some information about the furnace and your HVAC people stink at troubleshooting, throwing parts in hoping something solves it isn't very prudent. You make no mention if the "induction" fan and its sensor was checked for proper operation.

In the middle of panic to get shop ready for winter and wife tells me at 16:00 on Friday that the house furnace has failed. Looked at the error lights and decoded as ocwe temp that would result from blower motor failure, but wiring diagram gave NO info outside of where wires were connected. Being closing time, called around and found new motor (as it had failed once before) and dragged it home. Being a 5 speed motor, no info on how to test old one, so foolishly (but remembering the last one is as old as the previous failure one) put the new one in and once more found same failure code. No problem staying warm over weekend (barely freezing at night and good solar gain in day) and called in repair tech - who told me when he arrived he had a board in his bag and when we removed the old one what we would see. When he tested voltage at one particular point (that should have been 120 but was only 20) he confirmed that was liekly the failure point and when he removed it, there was the burn in exactly where he described. Learned that was a very common failure for my furnace and there was a thrid generation upgrade board and installation kit for that reason.

Bottom line: If you don't know your way around some piece of equipment, it is often very cost effective to hire someone who does.

 

[Fav Onefour]

I have to admit that I had no clue that error codes were (mostly) universal. I have quite a few different brands and I'm always digging to find the code list.
I'm not a fan of trying to diagnose this kind of stuff on open forums, but some of the problem sounds familiar.

My earlier example with pressure switch issues was related to that style sticking closed. They would allow the furnace to run and satisfy the stat. I can't remember the code shown, but the furnace would not fire on the next cycle.
The previous owner had techs try to find the issue, but the valve must have been back open by they time they showed up. The issue had been ongoing for some time when I bought the place. I tried monitoring heat cycles to narrow down the problem. The resident had made a practice of cranking the stat to the temperature of the sun because of the intermittent heating. I'm sure the previous tech never wanted to hang around long enough for the stat to satisfy and then go into the next cycle. I was able to narrow down the issue pretty fast by short cycling (five, maybe ten minutes), with the power switch.
I know the simple pressure switch is a long shot, but what the heck, it might be worth trying. The issue is hard to test because they do close. It also seems like handling them allowed them to pop open.

 

[Crazyjake8493]

Did you check the draft with a manometer? Or has anyone? Something could be reducing draft preventing the pressure switch from closing. Could be a partial blockage on the intake or exhaust. Could be condensate in the lines from the inducer housing to the pressure switch. Could be a cracked or broken condensate trap. Could be water in the inducer housing. Pressure switches could be malfunctioning or sticking. Inducer draft motor could be weak and not pulling enough draft.

It could be a bad heat exchanger but that should be visually verified or via a pressure test, not just a guess on their part. If it's too hard to get a visual on the heat exchanger, it can be pressure tested by removing intake & exhaust, taping off both, putting the tube from a manometer in the heat exchanger, and turning on the blower. If the heat exchanger starts to pressurize, that's a good indication it's been compromised somewhere.

Hard to tell without proper diagnosis. The "furnace guys" sound like parts changers with no diagnostic skills.

You could even check the board. I've had a few where there was enough dust accumulated on the back of the board to cause erratic behavior - called "carbon tracking." Could be a bad solder joint somewhere on the board. Also check your grounds for the flame sensor and inducer motor.

I had a problem with ours a few years ago that was a very intermittent pressure switch issue. Safety circuit would open for a fraction of a second and re-close - so fast that a meter wouldn't pick it up. Would cause the furnace to restart it's whole cycle multiple times. I verified proper draft with a manometer, and when I put the pressure switch on a draft simulator the light would flicker when it was right around it's rated pressure - bad/failing contacts. Cost me $12 and a lot of my sanity.

It could be multiple things here but until someone does the proper tests, you're just guessing and throwing parts at it. Someone needs to check draft with a manometer and ideally a combustion analyzer which any real HVAC tech would have.

 

[Steve_P]

I had a bad heat exchanger on my furnace ~15 years ago. The leak would blow out the flame, or similar, when it started (I can't remember the exact details). After a young guy totally blew the diagnosis and just reset the flame sensor, the next day the old guy correctly diagnosed it the high tech way by using a lighter and watching the flame flicker when it was on- due to air leakage from the HE. And when I removed it, it had multiple cracks.

 

[theoldwizard1]

Without going through the entire saga ... The root cause was a failed gas valve.

The first tech insisted on removing the igniter, even after I showed him the old one.

• Replaced control board, no success. Old one was reinstalled.
• Next day, a different tech, replaced gas valve. Worked intermittently.
• Two days later, a third tech ran a bunch of test. Ultimately decided there was a recall on the heat exchanger.
• 5 days later (weekend in between), the "field supervisor" replaced the heat exchanger.

No the way out the door, the supervisor said the heat exchanger likely had already been replaced, but he replaced it again. On careful inspection through the view port, he noticed that the flame was "rolling" (not steady). There was an air gap where the igniter was re-installed.

 

[Kuma601]

Wow...
Just curious how much they yanked the wallet for this scenario?

 

[Crazyjake8493]

Wow...
Just curious how much they yanked the wallet for this scenario?

Whatever it was, it was too much to charge considering they sound like "parts changers" and not actual technicians.