I recently purchased a Hampton Bay Quick Installation 52" indoor fan with light kit. I am replacing an existing fan with light kit in my master bedroom. The old fan had a switch for light control and a 5-position rheostat for fan control (Off-Low-Med-High-Off).

With my new fan, there are slots for four (4) wires to be inserted but the directions say to use only three (3). I have a Red (I presume Switched Hot), a Black (I presume Unswitched Hot), a White (Neutral?), and a Bare Ground.

After plugging only the Red, White, and Ground in there is no control from the Rheostat but full functionality from the pull strings at the fan. (The lights work and I am able to select variable speeds.) I switched the Red with Black (Black, White, Ground) and had no control from the switch and partial functionality at the fan (worked on High speed only - both fan and light).

There is nothing in the instructions about what to do with the fourth wire - there isn't even a mention of having a fourth wire. How can I get full functionality with all available wiring?

1. Is your new fan a remote fan?

2. What color wires come from the ceiling?

Ceiling Fan Wiring - Ceiling Fans N More

1. It is not a remote fan.

2. Red, Black, White, Bare

The red comes from the switch for the light. The black comes from the rheostat control for the fan.
If you want to use the rheostat, put fan on high with the pull chain and use rheostat to control speed.

There are places for three wires to connect to the fan. If I connect the black for the rheo, I have no functionality from the switch. If I connect the red from the switch, I have no functionality from the rheo. In both configurations, I am keeping the White and the Ground. Can I tie in the two hot leads?

You said you have 4 places to connect to the fan/light. You did not tell us what each does. Most often a fan/light will have a white neutral, a black to the fan motor, a blue or black/blue to the light. Your connection should in effect be the same. Right now I have no idea what the 4th connection is unless it is ground. It could be connection to both the fan motor and the light. Is this connector a place where you put the wires under screws or you stick wires into a spring type clamp. What color are the wires coming from the fan/light to the connector? Installation instructions should tell you what each connection point does or the connection points should be marked.

It's supposed to be

Fan black-black
Fan white-white
Fan blue-red
Ground-ground.

What make was the old fan? The wall control might not be compatible.

All right, I have no idea what type the old fan was. It came with the house and, I assume, was as old as the house making it about 10 years or so. The new fan (Hampton Bay) has what I believe are spring-type inserts capable of housing four wires. I don't know the color of the wires coming from the fan and light unit as they are all within the housing. The installation instructions talk of how to install using a typical three-wire installation from the house. There is no mention of a fourth wire.

To the best of my knowledge, I have laid out what I have. At the wall, I have a red and black coming from a switch. I have two blacks coming from the rheo. At the fan mounting box at the ceiling, I have four wires (Red, Black, White, and Bare). Aside from checking continuity between the ceiling and wall, I believe the Red is Switched Hot, the Black is Unswitched Hot (which would work with a rheo, correct?), the White is Neutral and the Bare is ground.

Again, I have no idea what is inside the fan in order to do a one-to-one attachment.

I do appreciate all the help I am getting, though. It is making it much more approachable rather than insurmountable.

Why are you talking about the wires inside the fan? Normally when installing a fan you only need to deal with the wires extending from the top of the fan.

You have confused me, pictures might help.