york diamond 80 model - P4HUB16N08001A furnace not working


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Old 10-25-13, 03:28 PM
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york diamond 80 model - P4HUB16N08001A furnace not working

Hello,
This is too fun not to share. I have been troubleshooting a furnace not working. Also I have noticeed that during this the fan blower is stuck on and will not shut off. I normally keep in set to "ON" but when set to "AUTO" it will not turn off.

The trouble shooting for the furnace not working leads me to believe that it is a either a control board problem or a draft inducer problem. The control board part # is S1-33103010000 should I need to replace it.

The NG 80% furnace model york diamond 80 model number is P4HUB16N08001A.

Trouoble shooting thus far:
replaced thermostat control unit with known good. Set unit to system heat and fan to auto.

went to furnace and tested for call for heat with multimeter for 24vac on C and W. Tested good.

Main problem symptoms are that control board led blinks continuous red - no code just rapid flashing. This diag indicator on control panel guide says "low flame sense signal". I have cleaned flame sensor with steel wool and reinserted.

When main power switch restores power the blower fan starts running and will not shut off. I suspect a relay, but have not looked at that at this time. The red light rapidly flashes and the inducer does not start. I wanted to start with the inducer. I was trying to measure voltage for the inducer and I think that I should have seen around 115V from what I have read, but when I removed the two leads and measured I didn't get voltage. I wanted to make sure that I was doing this correctly. When I measured the presuree switch it measured 27vac

I was thinking that with both the constant fan and no inducer with the "low flame sense signal" that the problem was a control board, but wanted to get input from others more knowledgeable than me. I want to concentrate on fixing heat first and blower fan should be secondary, and if it is control should take care of itself, maybe.

Thanks
 
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Old 10-25-13, 04:09 PM
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Describe in detail and in order the sequence of events which occurs when the thermostat calls for heat.

A furnace doesn't just "turn on." It goes through a sequence of events that eventually results min heat if the sequence is completed. Determining how far the furnace gets in this sequence is usually the key to determining what defects might be present.
 
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Old 10-25-13, 04:21 PM
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What I mean by turn on is that I switch on the master power (breaker). The sequence that I understand is that the call for heat is made by thermostat. That is being bone by 24v on C and W wires. Then the inducer should start- it does not. That is where I am starting to look. I epect that the two leads on the inducer when taken off should measure 115vac. It is not from my testing.
 
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Old 10-25-13, 04:45 PM
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york diamond 80 startup error - YouTube

I have posted a video of the startup sequence showing the led flashing and blower fan starting right away. I have disconnected the G from the control and the blower fan still turns on and stays on- will not turn off.
 
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Old 10-25-13, 04:53 PM
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Old 10-26-13, 01:21 PM
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blower fan is still non top running. I have just tested the limit switch and it measured 0 ohm. Limit switch is good. From what I understand the control board tests if this switch is closed and since I have verifed that it is closed I looked at voltage. I noticed that there is no detectable voltage from control board on the 2 wires. I expected ~24vac. So it looks like a bad control board. I have posted a video earlier that shows the startup sequence with led constant flashing which is supposed to mean low flame sense signal. I suppose I could replace the flame sensor and contol board just to be safe. Anyone else have any positive input?
 
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Old 11-04-13, 08:32 AM
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solved

I ordered the control panel and and replaced it this weekend. Problem solved
 
 

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