York Furnace blower on but no ignition

[RFair369]

I have a 21 year old furnace in great condition, per technician a day ago. The model number is P3CCD20N10601A. The tech came out because I had no ignition in my furnace no matter what I did. I am mechanically and electrically competent. I have worked in this field for 20 plus years and I just need a direction to go and a better understanding of what the furnace is trying to do so I can fix it. Anyways, the tech came out and found a bad ignitor. I have the part and it is open when measured with a meter so I somewhat trust him. Now the furnace lights off and heats the house BUT when the heater turns off after meeting setpoint and tries to run again later when the temp drops below setpoint all I get is a blower. I get no glow on the ignitor and I cannot smell gas. The blower will run and wait for something to happen. What is that something? I think somewhere in that comment I may be missing something because I am not sure what to look/listen for. All I can say is when the temp drops below the setpoint I hear the fan kick on, not the one that sends air to the vents. I wait and wait and wait to hear the flame fire up but it never does. To get it to work I just go above setpoint on my thermostat and the unit turns off and then I go below setpoint and now I get the infamous blower sound and then ignition about 1 minute later. I have suspicions such as a blower switch or a pressure switch but I don't have the know how to figure it out because I don't know what component comes first. Any help would be appreciated. I did look through the site but nothing stood out. I may have missed something though. I am going to continue to search the site. Thank you.

I have replaced the batteries in my thermostat.
I clean my filters every 3 months. (Anal retentive trait of mine)
The inside of the furnace is clean (see in parathese above...LOL)

[Freon]

You need to watch the furnace try and ignite while someone calls for heat. The sequence should be the small inducer blower will start and once it established the correct draft pressure then the ignitor will glow and shortly after the gas valve should open. If there is no flame, the flame sensor will stop the whole process and it will try again. After a certain number of failed ignition attempts the furnace control board should lock the furnace from further attempts to light.

You need to verify -

The ignitor glows white hot. I am assuming you have a Hot Surface Ignitor. If you do not see the ignitor glow then the pressure switch associated with the inducer blower is preventing it. If you look at the inducer assembly you should find 2 wires coming from a sensor located in the flue piping or close to it. Those wires should go to the control board.

If the ignitor glows then you should hear the gas valve open and gas flow into the combustion chamber. The gas should immediately ignite. If it doesn't, the flame sensor will not stop the process.

You need to verify the replacement HSI is the correct part. Verify it is installed correctly and in the correct location. Verify it always glows white hot when there's a call for heat. Make sure the burners are clean and gas is able to get close to the HSI for ignition. A 21 year old furnace may be a challenge to finding original replacement parts for.

[RFair369]

Freon, Thanks. I am busy at work but when I have time I am going to look into what you suggested. If I can get it to act up and test the things you suggested I will post the reults here.

[RFair369]

- Last night I watched as the furnace tried to start. The small blower came on, then the ignitor began to glow and then the gas turned on. Just as the gas was coming on the ignitor stopped glowing.

I took the hose off to the pressure switch and put a vacuum on the switch. I had to pump over and over on my manual vacuum because the hose would not hold the vacuum. The ignitor lit and the gas began to come on then the ignitor went out and the gas turned off.

I did find something of interest that I am testing right now. When I went to remove the hose from the blower and the pressure switch the hose broke off. I gather the heat and the age of the hose made it brittle. I did try the only hose I had around which was teflon and I found something else interesting. The hose end on the blower became saft and maluable and bent over and off the connection. There is a hot spot blowing on that blower fitting where the hose is installed. I put the old hose back on, minus the bad ends for now. I couldn't find the correct hose at Lowes so I purchase fuel hose for the time being IF I need it. I ordered the correct hose from Amazon today. I should see it in a few days.

I am now paying attention to whether or not my furnace lights up everytime it is called for. I will report back soon.

[RFair369]

Came home and the setting on thermostat was 70 and the actual temp was 65. The blower was running and no ignition. I watched for awhile and the same thing keeps happening. Blower on igniter glows red, gas comes on and then the igniter goes cold and the gas turns off. Over and over this happens. Any other ideas I can try? Jump out the press switch? If so which pins?

[Freon]

Normally, if the gas does not ignite immediately the flame sensor will shut down the whole furnace and then try to relight again. This seems to be what is happening to your furnace. From your description it seems the ignitor is not always able to ignite the gas because it is out of position or it is the wrong ignitor and the flame sensor, seeing no flame, shuts things off. I say the above because, again normally, if the draft inducer did not achieve the required draft as measured by the pressure sensor you have found at the end of the hose, then the ignitor would not glow nor would the gas valve open. Since the ignitor glows and the gas flows I am going to assume the inducer assembly is working correctly.

One test is to TEMPORARILY jumper the 2 wires coming from the draft inducer pressure switch. Jumping them will make the furnace think there's good pressure. Now if you still have ignition problems like before you know it's not the pressure switch.

One other possibility is combustion air flow. Make sure the flue is free of debris and the combustion chamber is clean. I still feel it's a matter of adjusting the burners relative to the ignitor assuming you have the correct ignitor. I hope the tech did not handle the ignitor with bare hands.

[RFair369]

Sorry so late on replying BUT.....I had enough of trying to troubleshoot my issue any further and called the same company back out who replaced the ignitor in the first place. He found that the ignitor was misaligned and one of the screws used to secure the ignitor was loose. Personally I did not see the misalignment when I inspected it from where I could see it. I also did not see a loose screw. If I were to make a suggestion to others with the same problem I would say really get in there and look closely. I think you (Freon) were close to helping me get it by mentioning the gas flow across the ignitor.

Freon I appreciate you replying to my post and trying to help me get this thing fixed. It amazes me how people like you give up free time to help others in need. Thanks again.