York Heater burners will not light

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  #1  
Old 12-27-17, 01:06 PM
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York Heater burners will not light

We have a York HVAC unit, model P3DHC16N07501C, approx 15 years old. On 12/24/2017, the heater stopped working. When the thermostat is turned to heat, the blower motor comes on but turns off a minute or so later. Had an HVAC tech come out to diagnose the problem yesterday and after observing the 3-light diagnostic code, stated it was either a bad air pressure switch, a defective blower motor, or a bad control board. His troubleshooting included removing the main control board to visually check for any obvious damage or burns to the components, and sucking on the pressure switch hoses. Even though his sucking on the PS hoses confirmed the switches were working, he insisted it was the condensation pan switch but they would replace both, for $488!. Seeing as he had not used a manometer or a DVM to confirm the bad switch, I wasn't convinced he found the problem or just one of the symptoms. Searching on-line, I found instructions on how to test the pressure switches. I measured 27VAC on the one side of the combustion blower pressure switch, nothing on the other side of switch. I measured 0 VAC on either side of the condensation pressure switch, and the 3-light diagnostic signal on the board. After removing the cover to the flame roll-out, exposing the burners, the 3-light indicator went away, I measured 27VAC on both sides of both pressure switches, and the burners ignited, resulting in the heater working fine. As soon as I place the cover back onto the flame roll-out chamber, the flames go out (as if the flames were robbed of air) and the 3-light diagnostic code returns. Any ideas what the underlying problem is or what to check next?
 
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  #2  
Old 12-27-17, 02:01 PM
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Check to see if the intake vent pipe is not blocked.
 
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Old 12-27-17, 04:27 PM
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https://www.repairclinic.com

Your roll out switch has a 200 deg. rating. Over that it will shut the burner down.

For some reason you are building up heat at the burners and the switch is doing its job unless it has become weak.

You could have an obstruction in the furnace or flue pipe but for some reason the heat is not venting up the chimney.

It could be just a poor draft situation and there may be nothing wrong with your furnace at all. Weather conditions create draft situations or down drafts.

I posted a link at the beginning for replacement parts for your unit if you're interested. Just hit search and your parts will come up.

Hope this helps a little.
 
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Old 12-27-17, 04:55 PM
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Reply with photos

I went atop the roof and confirmed no blockage of vent pipe, at least for the first 10 feet (used short fish tape). No obvious blockage of vent pipe from inside the burner box.
I found an unknown object lying against the bottom of the right burner, inside the burner box. I attached three photos of the object, in hopes that it can be identified.
 
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Old 12-27-17, 04:56 PM
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He didn't mention resetting the rollout switch so I don't think it's an overheat issue. He mentioned removing the burner cover which allowed the system to fire.

When you see a tech blowing in or sucking on a pressure switch.... run. Those switches are easily damaged by doing that. This is where a manometer is needed.One thing that does get overlooked is that there is a tiny hole in the draft inducer hose connection and they do have a tendency to get plugged. You need a fine piece of wire, a small paper clip or even a small drill bit to clean the hole.

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In your pictures are pieces of the hot surface igniter.
 
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Old 12-27-17, 05:03 PM
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That’s the igniter you found by the burner in pieces. Not going to work very well like that.
 
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Old 12-27-17, 05:24 PM
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...Had an HVAC tech come out to diagnose the problem yesterday and after observing the 3-light diagnostic code, stated it was either a bad air pressure switch, a defective blower motor, or a bad control board. His troubleshooting included removing the main control board to visually check for any obvious damage or burns to the components, and sucking on the pressure switch hoses. Even though his sucking on the PS hoses confirmed the switches were working, he insisted it was the condensation pan switch but they would replace both, for $488!
.

He was there and didn't give you the actual diagnosis? But still wanted to replace working safety switches?

But yeah, those are definitely broken pieces from an HSI (hot surface igniter). Is yours broken? Was it broken before all this poking around? They are quite fragile.

Are you sure we are talking about the "blower motor" in this context? Usually these pressure switches are related to the draft-inducer motor that pulls air through the combustion chambers. It would be rare to have an actual code flashed on the control board and the control board itself to be the issue.

He should have been able to instantly witness whether the draft-inducer motor came on or not and that should have been the next step before or after checking the pressure-switch circuit.
 
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Old 12-27-17, 08:28 PM
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Thanks Pete. I didn't see any clogs in the draft inducer connections but I cleaned everything out anyway.
The hot surface igniter was broken but laying against the right burner - apparently enough to actually ignite the burners. Unfortunately, when I pulled the broken pieces out from there, I removed what little bit was there and working. So, I will have to order a new HSI and install that before I can further troubleshoot the overall problem.
 
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Old 12-27-17, 08:35 PM
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It was working partially because parts of it were touching ground.
Be careful.... those igniters are extremely fragile. I've broken brand new ones installing therm.

I supply a diagram of the hose connection because people check the large port where the hose actually connects not realizing that there is a tiny hole all the way at the bottom.
 
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Old 12-27-17, 08:35 PM
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...The hot surface igniter was broken but laying against the right burner - apparently enough to actually ignite the burners....
This is likely the problem from the start of your current issues. Did you get to see the trouble code flashed by the control board?
 
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Old 12-28-17, 06:47 PM
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It's an older unit, so the code that flashed on the control board was a simple three red LED flashes. According to the tech, this indicates a faulty pressure switch. My problem with that was his lack of testing with appropriate test equipment and procedures to confirm this was the actual issue and not just one of the symptoms.
 
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Old 03-09-18, 08:37 AM
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PNWRich, I am having the same issue. Blinking red light 3X - Pressure Switch Stuck Open. Switch and vent pipes checked out fine per HVAC tech's tests. Suggestion was possible Inducer Motor. Furnace runs fine for a day and then shuts down. Resetting the system gets me another short, intermittent reprieve. Just curious what your solution was.
 
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Old 03-09-18, 11:33 AM
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If he is not sure it's the inducer motor find a new tech. Apparently he doesn't know what a monometer is or he doesn't have one.
 
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Old 03-09-18, 12:41 PM
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Originally Posted by gbeaner7 View Post
PNWRich, I am having the same issue. Blinking red light 3X - Pressure Switch Stuck Open. Switch and vent pipes checked out fine per HVAC tech's tests. Suggestion was possible Inducer Motor. Furnace runs fine for a day and then shuts down. Resetting the system gets me another short, intermittent reprieve. Just curious what your solution was.
I'm having the same problem as you. I have not been able to figure it out. I don't get a day out of it, but about 8 hours or so.
 
  #15  
Old 03-13-18, 06:40 AM
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patmann, I have gone two days with no issue now. The Tech did confirm PS was getting 24V and the manometer showed pressure (WC) was within spec. When he was here, the unit did not fail, so of course they were good. Taking the advice of others, I cleaned out the nipple going into the inducer from the PS after seeing a lot of water in the tube. I have also gone to manually operating my programmable thermostat. It was previously set at 61 while sleeping and programmed at 69 at 7am. I also made a slight adjustment in my exhaust valve to insure 1/4" rise per foot. I am thinking the clogged nipple was the issue. I will wait a few more days before going back to "program" mode on thermostat. Good luck!
 
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