Im trying to install a furnace heater in our carrier furnace. The instructions on the new heater says to install the grey, orange, and blue wires in 1-2-3 of the blower tap connection. Our furnace has C-1-2-3-4. Do I put the wires in C-1-2 or skip C and put them in 1-2-3?

No way to help you with out knowing exactly what you are working with,, furnaces have model numbers that are extreamly important,, also need to know more about the part you are installing

The furnace model number is 40AQ030300BB. I might have been mistaken on the connection. They are not the grey, orange, blue. They are the black and red. But still don't know what the "C" is for on the blower tap connection. Also the wires that get connected to the wires coming in from the thermostat wires don't match colors. I have gray, orange and blue.

First off the carrier heater units come with a wiring diagram.

You stated this
The instructions on the new heater says to install the grey, orange, and blue wires in 1-2-3 of the blower tap connection. Our furnace has C-1-2-3-4. Do I put the wires in C-1-2 or skip C and put them in 1-2-3?

Now think about what you said it said to do. It said to install the wires in 1,2,3, of the blower tap. Now think real hard it did not say anything about C or 4 did it.

Did you research this heater and is it the correct one for your unit to start with? Carrier is really good when it comes to its instructions so I am sure they did not make a mistake.

Its supposed to be a compatible unit to the carrier model. I was wrong on my first question I don't think those were the correct wires that go into blower. The gray orange and blue go to the thermostat wires going into the furnace, I think. But the connection is different, it has screws and the heater has a plastic connection.

I apologize I haven't explained this correctly. I bought a furnace heater electric kit that is supposed to be compatible with our carrier's heater electric kit. But the wires coming from the thermastat to the furnace are different colors then the wires from the new heater kit that should connect to those wires.

Wow that sounds like a problem for sure. Without the proper item to be installed I cannot be of much help. If it is not from the furnace company itself then you should not use it. Sorry