[mtdugge]

I have a York furnace model P2MPD12N06401B that intermittently will not light, and blows cold air in the house. The sequence of events is:
1. On call for heat, exhaust blower comes on.
2. About 15 sec later, ignitor (at far right burner) glows bright orange.
3. A click can be heard, but burners do not ignite. Very faint gas smell.
4. Ingitor cools down again.
5. Steps 2-4 repeat two more times.
6. Blower motor comes on, exhaust motor goes off, and control board LED flashes 7 times. Cool air blows into house.

I had this problem in March 2012, and replaced control board based on discussion with online parts supplier. It worked fine for the rest of last winter's heating season. Note that unit runs on propane, I have gas, and two other furnaces (not same model) in the same location, fed by same gas line, work fine.

 

[yuri]

Could be several problems. More than likely the gas valve is sticking and not opening properly and giving enough pressure. Would need to have a Pro with a manometer check the manifold pressure when this happens. Sometimes we have to cycle the unit 2 dozen times B4 it acts up and sticks but 95% of the time it will. Most techs are not patient enough to do that but an experienced one knows better.

Burners may be dirty and gas is not hitting the igniter properly or the igniter is dying and not the exact color of orange it takes to light the gas. The resistance or it and color ( gives U an ignition temp and is important ). I would get the Pro to check the ohms resistance and compare it to a new one.

Igniter may be slightly off center and not exactly in the gas stream but that is VERY rare and only if a inexperienced tech installed it.

 

[mtdugge]

Thanks Yuri. I would have replied earlier but did not see your reply until I searched for my message in the postings. I'll get a local pro to check the pressure with a manometer and the ignitor resistance as you suggest.