"FAN ON" switch causes AC to be on all the time

Yes, that's what I thought also. Since my AC and Heat are working fine and the fan is working properly for both, just how could a wire be switched? I would think that one part of the system wouldn't work at all if that were the case.

Yes, I have a humidifier connected to the furnace, but it works fine. When I turn off the humidistat, the humidifier never goes on. I believe the furnace only provides a power transformer for the humidifier. The actual switch is in my dining room next to the thermostat.

Perhaps I should unwrap the electrical tape for the wires that are above the furnace and see if some bare wires are inadvertently touching.

I like my neighbor, but I sure hope he doesn't make my problem worse!

Keep the suggestions coming....if anyone has anything else to add or ask. I really appreciate your help!

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Originally Posted by HVACTechNC

Whatch'a talkin' 'bout Willis?

If that were the case then why wouldn't the voltage "back feed" through the stat even if it were wired properly and still bring on the condenser? The thermostat doesn't know or care which color wire is connected to which terminal and to what piece of equipment it goes to. I'm not following your logic on this one, please explain further.

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How does the thermostat turn on the fan on a call for cooling? If you think about this, you will get to the point I am making. Think about the relationship of the Heat-off-Cool switch and the fan. You will get there. Willis?

Maybe wires shorted together, or just bad tstat.

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Originally Posted by trouble time

How does the thermostat turn on the fan on a call for cooling? If you think about this, you will get to the point I am making. Think about the relationship of the Heat-off-Cool switch and the fan. You will get there. Willis?

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What'cha talkin' 'bout Willis? Is a line from an old TV show - Different Strokes.

Still not completely sure I follow your logic. I will PM you...

Some furnaces have a "Y" terminal that activates the cooling speed regardless of if the "G" is energized. My Carrier works this way, YMMV. If the "Y" and "G" were reversed at the stat it would work normally until you turn the fan to "On", then it would run the A/C.

That makes sense. I work on more heat pumps than furnaces, so I wasn't thinking about the furnace control board and its impact on this situation...

Eureka

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Originally Posted by tac0967

Yes, that's what I thought also. Since my AC and Heat are working fine and the fan is working properly for both, just how could a wire be switched? I would think that one part of the system wouldn't work at all if that were the case.

Yes, I have a humidifier connected to the furnace, but it works fine. When I turn off the humidistat, the humidifier never goes on. I believe the furnace only provides a power transformer for the humidifier. The actual switch is in my dining room next to the thermostat.

Perhaps I should unwrap the electrical tape for the wires that are above the furnace and see if some bare wires are inadvertently touching.

I like my neighbor, but I sure hope he doesn't make my problem worse!

Keep the suggestions coming....if anyone has anything else to add or ask. I really appreciate your help!

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Is the humidifier a recent addition? I have seen plenty of miswired humidifiers do exactly what you are experiencing.

Unbelieveable!!!!!!!!!!!!!!!!!!

OP, let you neighbor do his thing and don't loose any sleep over it.

Please tell us what kind of thermostat you have. Is it an old style of with a mercury bulb or an electronic one?

Is there a thread in the pro section yet? We need to talk.

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Originally Posted by Milk man

Unbelieveable!!!!!!!!!!!!!!!!!!

OP, let you neighbor do his thing and don't loose any sleep over it.

Please tell us what kind of thermostat you have. Is it an old style of with a mercury bulb or an electronic one?

Is there a thread in the pro section yet? We need to talk.

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LOL! Sounds like you have an idea you'd like to share with us :cheers:

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Originally Posted by RoBoTeq

LOL! Sounds like you have an idea you'd like to share with us :cheers:

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Yes, I started a thread in the pro residential section
http://hvac-talk.com/vbb/showthread.php?t=921832

I think that anyone clicking that link can see that thread. Better to just post the name of the thread.

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Originally Posted by RoBoTeq

I think that anyone clicking that link can see that thread. Better to just post the name of the thread.

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I loged out and tried to follow the link. Would not let me, so I think we are good. It is in a private area.

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Originally Posted by HVACTechNC

If the wires were just switched when he puts the thermostat to "on" for the fan the condenser would come on, but not the blower fan. he said they both do.

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many new furnace boards automatically bring on the blower when they receive 24 volts on the Y terminal. So it could easily be that the wires are switched.