Air Conditioning - a/c booster fan

I installed a booster fan in my a/c - heat duct, I was wanting to know how to wire it where it would come on when the unit does? its a 115v fan, thanks

Run wire back to the blower. Might have to use a relay there if the blower motor is 220V. Be sure and check it out. Or run 24V to relay from blower control by fan and pick up 110V thereat that fan.

My blower is 220 but the relay is built in it, the only wires going to it are a yellow common and a black where you choose the fan speed, and they are only 16ga wires

You have 24V going to a relay from the tstat that turns the blower on. Now if you pick that up and run it to a relay by that fan . The relay can turn on a 110V to that fan for you when the blower comes on. look at the wire schematic should be on the blower door . Find the blower relay.;)

Sounds like a good plan I will give it a shot, thanks

Ok tell me where I messed up, I picked up at the fan relay at 24v one on hot and one on common ran it to a 24v/115 relay by the booster fan and when I turned the tstat on (fan only) it burned up the relay by the booster fan, thanks

Is it possible that perhaps you feed hot & neutral to the coil terminals? Feeding 120V t a 24V load (the coil in this case) will smoke it for sure.

You should have come to the coil of the relay with a wire from the yellow terminal and a second one from the "C" terminal...of your unit (the terminal board).

On the power side, A hot and a neutral from the same terminals that would turn your house blower ON.

I didnt have the 115v hooked up at all only the 24v, and the setup Im using doesnt have a coil, just a relay,thanks

You have two wires at the blower relay . When hot and the blower is on you have 24V there. Now you run the two wires from there on over to this other relay by the other fan. So when the blower comes on the 24V wire will turn on the other relay also. That will feed the 110V to the new fan.
A relay has a coil in it . That is what will close the relay when power is put to it

That is how I had it hooked up, I checked it with a meter an it has 24v but when I turned it on it started buzzing and then smoking, is it possible to hook them up backwards there was only 24v there I didnt have the 115 hooked up, also this is the second winter that my service disconnect box has melted at the disconnect blade it is the same amps as the breaker feeding it should I go higher, thanks

Ok big mistake on my part, I must have had the meter on DC and it read 24.6v which was really 246vAC, which tstat wires should I hook to, its a four wire, cause I can only find 240vac at the blower, and on the disconnect its on the heat side and its a 4ton package unit, thanks

You really need a wiring diagram because describing wiring scenarios in text is very difficult. It sounds like you had the hot side of the transformer secondary fed to your relay twice.
You could take one of those wires and put it on your relay coil (most relays have a little wiring diagram on them that tells you the the coil, usually terminals 1 and 3) and take another wire from the other coil terminal to metal somwhere and the relay will probably work then just break the line voltage to your fan on a normally open switch.

You can find wiring diagrams on
http://www.howtorepairairconditioners.com/