I have a 94 Accord EX (135k) and the termperature control slider knob will only go from all the way on the cold side (blue), to about 2/3 of the way toward the hot side (red). I have had to replace the knobs before, so I took the knob off and the know is fine. It's the post--that it attaches to--that won't turn. The A/C still works fine, but the heater is not coming on...I think it's because the knob won't let us get to "hot."

Searches of other threads say to check the "blend door" or the "blend door actuator". Could that be the problem? Maybe the door is stuck?

Any idea on where to find the door, and how to fix it? If it's not DIY, should I take it to the dealer, or would Pep Boys know how to fix it?

Thanks!!

The temperature control knob is connected to a cable that runs out through the firewall and opens or closes the heater control valve. Open your hood, look from the passenger side of the car, down by the bottom of the firewall, you'll see the hose running into the firewall, with a little knob/switch on it. That's the heater control valve. The switch has the end of a cable wrapped around it, the other end is attached to the temperature control knob.

You can reach your arm down behind the air intake tube and open or close that valve manually. On my car, the temperature control knob would go all the way from hot to cold, but it will only close the valve 80% of the way when set to cold. If I want to completely close the valve, I have to pop the hood and do it manually.

If you can open and close the valve with your hand, then you may need to get a new control cable. Its about $5 from the dealer, plus the labor for whoever you get to install it.

If you heater control valve itself is broken, that's gonna be a bit more involved.