Even during mild Las Cruces winters, you don’t need your AC. But, did you know that your AC can still be useful in the winter…as a defroster? Your AC is effective for windshield defrosting with or without your heated defroster on.
Frost and Your Windshield
You don’t need to defrost your windshield every morning it’s cold—only on mornings when there has been enough moisture in the air to collect and freeze on your windshield.
It’s the presence of moisture that causes frost…which is why you may have noticed sometimes when you’re trying to defrost your windshield using your heater, you see the frost getting worse instead of better. That’s because the air in your heating system is from the outside, so it has the same moisture content. When that moisture hits your cold glass, it makes causes new frost crystals to form (or at the very least, condenses into fog).
Why Your AC Works Defrosting Magic
Even if you have your AC set to pull in air from outside, the air is cooled by the coils filled with refrigerant. The cooling process significantly dehumidifies the air. When you blast your AC through the defrost vents, the air warming the glass is virtually free of moisture, and that keeps new frost from forming.
The bottom line: on mornings when you do not want to get out and scrape your windshield, turn your AC on with your defroster. Your windshield will clear faster than with your heater on alone.
P.S. Using your AC as a defroster will also ensure that your air conditioning system gets some use during the winter months. This keeps fluids moving through the system so that the moving parts get lubricated, and that may spare you some maintenance when warmer temperatures roll around and you do need your AC to cool your cabin.