Dumb HVAC question

[Elfer]

I have an HVAC in the attic and in the basement. I'm not sure exactly how the system is supposed to work. For instance, with the nice weather and the a/c switched to off, I could hear the 'unit' sort of buzzing. faint but annoying kind of like a refrigerator. I went downstairs and saw a switch like a normal light switch that said 'furnace on/off' I turned it off and the sound went away. I've never messed with the 'furnace' switch before. I'm guessing that the furnace should be 'off' during the summer a/c season and back to on when cold weather rolls around???

thanks...

[BlackTalon]

the fan unit is in the furnace at my house. 'heat' should not be runnung if switched off at thermostat

[Vicegrip]

the light switch turns the 120V off to the system. That also turns off the 120 to 24V transformer. The buzzing might be the transformer or a relay. The transformer is energized 24/7/365 regardless of the system "doing" anything. without 120 and 24 volts you will not have AC or heat. If the thermostat is a memory type it will retain the programing if it has a battery but it will drain the battery.

[Elfer]

thanks for the replys

would the buzzing mean it needs a new relay?

[Trak Ratt]

thanks for the replys

would the buzzing mean it needs a new relay?

Or the other thingy he mentioned.

[Roo]

If the transformer is the buzzing culprit, tapping it MAY change or stop the buzzing. Otherwise, with the power off, you can unmount and remount the transformer. This will sometimes changes the "rigidity" of the assembly and move electrical harmonics out of the range that causes the buzzing.
Likely solution, replace the transformer. The 120/24 transformers are only about $20.00 and available at most hardware stores. To replace, turn off the switch to the furnace, turn off the breaker supplying power to the furnace (just for safety in case something isn't grounded properly), disconnect the transformer wires, remove/replace the transformer, reconnect the wires, turn on the breaker, turn on the furnace switch.

[Elfer]

If the transformer is the buzzing culprit, tapping it MAY change or stop the buzzing. Otherwise, with the power off, you can unmount and remount the transformer. This will sometimes changes the "rigidity" of the assembly and move electrical harmonics out of the range that causes the buzzing.
Likely solution, replace the transformer. The 120/24 transformers are only about $20.00 and available at most hardware stores. To replace, turn off the switch to the furnace, turn off the breaker supplying power to the furnace (just for safety in case something isn't grounded properly), disconnect the transformer wires, remove/replace the transformer, reconnect the wires, turn on the breaker, turn on the furnace switch.

thank you very much. I will give it a whirl...

[Elfer]

i turned the furnace switch back on and now the 'heat' won't turn on. it's a gas powered unit. is there a pilot light somewhere i need to check? i also wonder if it isn't just the 'electronic' key pad. i replaced the battery but now only the a/c blows out of the vents. when i switch to heat, no air coming from vents....

[BlackTalon]

There are two things, the fire and the fan. Is the pilot igniting the compustion chamber, but the fan is not working to circulate the air through the ducts? is the fan working, but the combustion chamber is not igniting? Are neither working?

[Vicegrip]

Too much to type. Pm me if you want to talk this one through.

is the stat set for heat?

[Trak Ratt]

is the stat set for heat?That's the first thing I thought! That or set high enough to actually call for heat.

[Elfer]

There are two things, the fire and the fan. Is the pilot igniting the compustion chamber, but the fan is not working to circulate the air through the ducts? is the fan working, but the combustion chamber is not igniting? Are neither working?

the flux capacitor is getting about 400 gigawatts... not sure about ignition. fan does work if you turn on a/c. turn on heat to 80 plus, no fan blowing hot air out of the ducts... I had used the light switch thingy that says furnace on/off... turned it off because of the humming sound. turned it back on, but getting no heat. not sure if there is a pilot light involved because there is a natural gas pipe running into the unit, so i was thinking furnace off kills a pilot light? but still that doesn't account for the fan not turning on and circulating air with the heat on. if i switch to a/c though, air / fan does run...

[Elfer]

That's the first thing I thought! That or set high enough to actually call for heat.

set for heat... and high.... no joy

[Elfer]

1 million billion thanks to vicegrip... heat working.. nice and toasty, guess I should move it down from 80 now... :D :D :D

owe you big time.