Galant door wont open for my heat - 2003 Mitsubishi Galant

I'm assuming you mean the door under the dash that controls your heat. I had the exact same problem, yes it was the heater control valve, the repair was 285.00 approx 3 years ago. The tech that replaced it told me it is a common problem for the Galant. He said that if you keep your temp selector on either all hot or all cold that it keeps constant pressure on the plastic gear teeth in the valve. As they break off one by one you begin to hear that clicking noise as the dont catch. When you finally break off the last one it stops working.

According to him if you always leave the dial at least one notch from fully hot or fully cold you will not experience a failure of the switch. I have followed his advise and have had no further problems.

As for is it easily fixed.....no, the heater control valve needs to be replaced. I looked into doing it myself but thought better of it. Its buried deep in the dash and most of the passenger side must be removed and I still couldn't figure out how to get it out.