On a 2001 Honda Civic. Having the temp dial to HOT. When I turn the air flow dial from FRONT to Defrost (windshield), it turns on the A/C button and the A/C motor kicks in also. It just started doing this. So now I can't defrost my windshield. Air flow does come out the windshield. No check engine light. Please help.
This is normal behavior. The A/C system is turned on to dehumidify the air, which causes the windshield to defog. Without it, your breath would freeze on the inside of the windshield and cause further issues.
DIY: Turn Off Automatic A/C Turn-On What you will need: Two Fingers
Time Needed: 10 seconds.
Annoyed with how you can't turn off the A/C when you turn to defog? Here's the override (realize that A/C expediates the defog process).
You will now have control of your A/C regardless of what setting you are in, to revert back, simply repeat the procedue.