york diamond 80 p4hub16l08001a not turning on


Old 01-08-16, 01:36 PM
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york diamond 80 p4hub16l08001a not turning on

I am purchasing a house with a York Diamond 80 furnace. On propane. It is a foreclosure and so I am going to be responsible to fix it.

On my first trip out, it acted as if it had no power. I verified that the outlet it is plugged into did infact have power via multimeter. It does not turn on at all and the diagnostic LED light does not flash. While taking the front covers off, jostling around and before I managed to remove the cover, the blower kicked on for about 3 seconds and then turned off by itself. The fuse is not blown (atleast the only one I saw, 3amp automotive type).

I had replaced the thermostat before diagnosing it as it was also not working, and am about 95% sure I installed the new one correctly - I quadruple checked it against the instructions and am only not 100% positive because it obviously never ran as installed and I am not an HVAC expert. Though the blower kicking on for a few seconds also leads me to believe it is installed correctly.

My thought process is either A) the door switch, B) computer board or C) I do in fact have the thermostat installed incorrectly.

I plan to try to jump the lead on the door switch to see if it kicks it on and will check the thermostat again. Any other advice is appreciated - otherwise I'll just have to get an HVAC technician to take a peek.
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Old 01-08-16, 03:18 PM
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Take the blower panel off and manually press the door switch. See if you get an LED code.
Old 01-08-16, 04:43 PM
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Tried that already, nothing.
Old 01-08-16, 10:25 PM
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Welcome to the forums.

Shouldn't be too hard to figure out. Check the door switch. Then check for 120vac at the white and black connections on the board. If they are good.... check the transformer for 24vac.

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Old 01-09-16, 02:42 PM
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What happens if you pull the bottom door and hold the switch in? My switch after a few years was very finicky. I ended up putting a piece of rubber on the panel to push the switch in more as it was just barely disengaging. You may also want to wiggle every connection on every terminal as you may have some corrosion. The proper sequence for the furnace is that the inducer will start, then after about 5 seconds the igniter will glow and then the gas valve will open. Once the gas ignites, if the flame sensor detects proper heat temp the main blower will then turn on. Theres an inline fuse wire going into the control panel thats mounted to the blower housing.

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