In the winter, one constant issue we have to deal with, is frigid temperatures it effects everything from your ability to see, to your ability to drive, and your ability to stop. Moisture in the air system is particularly troublesome, and will cause most of the freezing issues. When doing your pretrip inspection, be sure to drain down the air tanks. This will remove the condensation that compressed air accumulates. Granted, all trucks (and even some trailers) have stand alone air dryers to remove the moisture, but they can and do occasionally fail. Moisture in the air lines can and does cause the levelling valve to malfunction, causing an improper ride height, as well as it is an audible airleak, that will get you placed out of service if found at a scale. To free up a frozen levelling valve, use a hammer to gently tap on the valve. Don’t haul off, and swing like you’re trying to hit a home run. A few gentle taps with a hammer should free it up. Even if the moisture doesn’t full block the airlines,
It can restrict the amount of air going to the brake pots, thereby reducing your braking effectiveness. Depending on the features of your truck, anything that uses the air can be affected by moisture in the air lines. The height of your seat, heater controls, wipers, etc. anything dependant on the air system could be compromised by moisture in the system, so do yourself, and everyone else a favour, and drain those tanks daily.