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mjcfromct 10-17-2011 10:24 PM

Fixed pilot light, now furnace or AC won't turn on
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A bit of history,

This is a 20-something year old York central air system and gas furnace. Central air worked all summer.

The pilot light on the furnace went out some time in the last few months (last time I saw it on was July).

The pilot light wouldn't re-light, so I replaced the thermocouple. Now the pilot light stays lit.

However, now the furnace will not turn on. I set the thermostat to "heat", hear the thermsotat click on, but nothing happens on the furnace unit itself. What is also interesting is if I set the thermostat to "cool" and turn it down below room temp, the AC will not kick on (outdoor unit AND blower).

The furnace has what appears to be a test button, seen at the far bottom of my attached picture. When I press that while the thermostat is set to "heat", the burner lights up. As soon as I let go, the gas shuts off. When the thermostat is set to "cool" and I press that button, the blower motor turns on (outdoor unit does not).

I think I'm missing something simple here. When I changed the pilot light TC, the only things I touched were the thermocouple wire, the pilot light gas tube, and shut off the electricity to the furnace via the switch on the far right of the attached picture.

Any thoughts as to where to start troubleshooting? Thanks in advance!

hvactech126 10-17-2011 10:30 PM

there is a blower door switch.... the blower door must be on........ depending on your thermostat when you remove power and then return power to the stat it has a 5 min delay before turning on the outdoor unit.

mjcfromct 10-17-2011 10:46 PM


You confirmed something for me - I was missing something simple!

What I incorrectly called a "test button" in my original post was the door switch. I had the blower door off the whole time!

Thanks for pointing out the obvious. Sometimes folks need that. :)

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