I'm tring to install a dual slide dimmer switch to a ceiling fan with a light. The wall box has a black, yellow and red wire in it. the dimmer control also has a black,yellow and red wire. So I hooked up the wires and the light slide controls both the fan and light and the fan slide does nothing. Does nayone know what the problem is?

Maybe an extra lead that ran up to ceiling box. Sometimes electricians run three wire for extra functions like ceiling fan / light combos.

I doubt it. They are designed for a 3 wire cable going to a ceiling fan with 2 loads. They likely would not design a special 2 in one switch if one side is a 3 way. You will have to have 2 switches and a double box to do the same job.

The white to your fan will connect to the white in the switch box, The switch itself should have a wire labeled com or common. This is where the Hot in your switch box will attach. The other two wires will be your switch legs to theto the fan. (Red and Black)

http://www.broan.com/common/productDigitalAssethandler.ashx?id=e07a9916-6b3e-4456-b00e-2edfad475df2

For starters, look at the wall switch. Are there two switches? If so, connect the black wire from the ceiling box to the black wire from the fan. Connect the red wire from the ceiling box to the blue wire from the fan. Connect white to white. At the fan, usually the black wire goes to the fan and the blue wire goes the the light.

If there is only one wall switch, you may or may not want to install a double switch so the fan and light can be controlled separately. If there is only one wall switch, most people just connect the wire connected to that switch (usually the black) to both the black and blue from the fan, not using the red at all. In that scenario both the light and the fan are switch at the fan as needed after the wall switch is operated.

Installing the extra red wire is not usual practice, someone actually was planning for future use and convenience.

Question needs more details. Let me answer as if you have one light and one switch, and one cable coming into switch box from ceiling.

Usually a switch-dimmer combo operates 2 different Loads (lights).
One light is controlled by switch, other by dimmer.

If power source is in ceiling, then one cable enters switch box.
Cable has black, white and ground wires
Old switch had 2 brass screws where black and white wires connect
Black wire brings Hot down from ceiling, and white wire connects back to Load (fan).
Neutral wires are in ceiling box, and not inside switch box, and are discussed.

With new dimmer: Black Hot wire from ceiling connects to dimmer black wire.
White Load wire connects to one of the red wires.
The other red wire goes to another Load, which is unknown at this point.

Add a comment for more free help. Say what cables and wires enter box, and what Loads you are controlling. Also add exact model number so expert can reference manual. Levition instruction sheets and manuals usually have toll free number.

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I wish we had more information to go on here.

1) You have 2 cables to to the Heat-Vent-Light
One cable is 12-3 and 1 cable is 12-3

2) That's where it's gets fuzzy.
What color wires are on HentVentLight?
Is power at the ceiling box or at the wall box?
What other wires are inside the wall box?
What kind of switch are you installing?

3) With that number of wires, it sounds like power is at ceiling box.
Power would arrive at ceiling box on one cable that has a Hot-black and Neutral-white wire.

4) Start at wall box:
Let's suppose you are installing a wall device that has 3 individual switches, with one switch for each HentVentLight.
The Hot wire from ceiling box would drop down into wall box on a black wire, and this wire connects to brass screw on switch.
Wire going to heater connects to one of the silver screws.
Wire to fan to another silver screw
Wire to light to another silver screw.

5) Work at ceiling box:
Let's suppose your HentVentLight has 4 wires: Black for light, Red for fan, Blue for heater, and White Neutral.
The white neutral connects to Neutral wire as described in #3.
Black, Red and Blue connect to each of the wires that come up from switch.

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As a general rule for timers and dimmers:

The Black dimmer wire connects to black hot wire coming from breaker (122V line)
The red dimmer wire connects to Load (wire going to chandelier)

The wall red wire that is capped could be a couple different things. a) It could go to a second switch that was used to control the chandelier. b) it could be another wire that goes to same ceiling box as chandelier to be used to control a fan, except you don't have a fan. In the second case, if you install a fan with a light, you could control fan and light separately.

The green is a ground wire that connects to bare copper wire in box. The bare copper connect back to main breaker box on the Neutral busbar.
White wires that are twisted together inside your light switch box also connect back to to main breaker box on the Neutral busbar.
The ground wire and neutral are a redundant safety system to protect you from electrical devices and appliances that have 'shorted'
The black hot wire connects back to the circuit breaker.

For example, each circuit breaker controls one area of household lighting. The black white and copper wires leave breaker box in a single romex cable. The romex travels to a junction box in the area where the lights are located. The junction box is usually a switch box or a ceiling box. From the junction box, the romex travels to each other switch, light and receptacle box in the area. So each box has 1 hot and 1 neutral and 1 ground that is connected in a line that leads back to breaker box.

Here's a couple pages that make home wiring easier to understand:
http://waterheatertimer.org/See-inside-main-breaker-box.html
http://waterheatertimer.org/240-v-water-heater-circuit.html
http://waterheatertimer.org/Install-owb.html

You're correct. The dimmer switch was not made for that fan.

The Green is ground > so you're right there too. I assume other plugs nearby are working when dimmer is on. Check that to make sure.

By your description, I assume there is NOT another switch or dimmer that connects to same light. If so, you need a 3-way switch and the following instructions are void.

I suspect when you wired the new fan, that you saw the red and small black wires in the ceiling box. Did you connect the fan and light to those wires? If so, the following information will help you wire the switch.

Your incoming Hot line is probably the larger black wire that connects to Dimmer black >>> this wire will connect to either screw on the new switch

To test Hot wire for sure: Take out dimmer and mark wires for identification. Separate wires. Turn on power and test each wire to bare ground. Tape tester leads to wood sticks so hands are away from power. You'll be fine. Tester lights up on Hot wire.

Next: The smaller black and a red wires are a toss up.

Here's how I would proceed. Connect the black Hot to either screw on switch. Connect red wire to other screw. Put wire nut over small black. Turn on power. Flip switch. Check both lights and fan to see which works with red wire.

Next reverse the toss up wires. Put wire nut over red. Connect small black to switch. Check both lights and fan.

If red and small black control the light & fan, then connect them together on the same screw, and you're done.

If you want to control the fan and light separately, buy double switch, and then Hot connects to dark-colored screw on one side of switch, and red and small black connect to two different screws on opposite side of switch.

The key seems to be that you changed wiring in the ceiling box.

I suggest you make a drawing of the wires before and after. Track the route that the Hot wire takes.

The key question is this: Does Hot wire from breaker box arrive in the ceiling box first? Or does it arrive in wall box first?

I think Hot from breaker arrives in wall box first. And from there Hot wire goes to ceiling box ... and from ceiling box the hot wire goes to other plugs in room. If this is true, you will be one wire short for installing fan control switch.

I always make a drawing of existing wires before starting, so I can put it back the way it was. It sounds like you got a good handle on which wire goes where.

We used to solve the one-wire-short problem by making a simple project bigger. Figure out which direction ceiling joist run. See if you can slide fish line from fan ceiling box over to wall. If that works. Over at the wall, chop small hole in ceiling so you can feed wire up to fish line. Pull wire over to ceiling box. Next, staple other end of wire along ceiling over to location above wall box. Chop another small hole so you can feed wire down to wall box. And then install beautiful crown molding to hide the mess, and paint the room so you need new furniture.

The light track series, just connect them in each side of the special plug in connection for the bulb, for the dual dimmer the red goes to red, the white goes to yellow and the black goes to black