It sounds like the keyed socket on the inside of the plastic round
control has broken. Have you pulled the black round plastic control
nob off to see?

Mine broke a couple of years ago and I did a crude repair job on it
with a little plastic cement. The controls for the fan and temperature
settings are the same and I switched them as the temperature setting
control places less torque on the keyed socket. I haven't have a
problem with either since making the repair and switch.

Elbert wrote:
> Any Honda mechanics hang out here?
>
> Anyway.... I have a 1999 Honda Accord EX... with
> the manual heater / AC controls. My switch to control
> the fan speed only works on one speed and I can feel
> that the switch has "slack" in it so its my assumption
> that the heater control unit needs to be replaced?
>
> I believe Honda calls this item the heater control unit...
> while other manufactures may call it the A/C control head.
>
> Is it basically a direct swap out to change one of these, it
> anyone knows.
>
> I'm talking about the control unit in the dash that operates
> the heater / ac fan speed and the temp.
>
> Thanks, Elbert
> -----------
> Elbert
> ask@me.com