Vehicle Winterization: How to Avoid Frozen Air Lines in Winter
Every winter, fleet drivers face weather-related hazards that can impact safety and bring operations to a halt. Think of hazards such as icy roads, freezing temperatures, poor visibility, and high winds.
Proactively winterizing your vehicles helps mitigate the impact of weather-related conditions and keeps your fleet safe and reliable. Though preparing your fleet vehicles for winter isn’t complicated, it’s absolutely critical.
Winterization requires performing preventive maintenance checks across key components to ensure your fleet is ready for the harshest winter conditions, including:
- Air system
- Engine and fuel systems
- Battery voltage
- Brake system
- Heating and defrosting system
- Lights and electrical system
- Exhaust system
- Tires
- Fuel levels
While all are equally important for vehicle winterizing purposes, in this blog, we’ll take a closer look at one particular component. It’s one that’s often overlooked, but one that winter conditions can be particularly tough on: the air system.
Air System: Not to Be Taken Lightly
In semi-trucks, tractor-trailers, dump trucks, and other large commercial vehicles, the air system (or compressed air system) powers braking and several non-braking functions. These functions include suspension, horns, automated manual transmission, and cab or seat adjustments.
Clean, dry air is essential for proper system operation. If not properly maintained, moisture can enter the air lines, affecting their operation and increasing the risk of brake and valve malfunctions. While moisture can be a problem year-round, winter is particularly problematic since the moisture is more likely to freeze.
Here’s how that happens.
When the compressor draws in air, it also pulls in moisture, which passes to the air dryer. The air dryer’s job is to stop that moisture from moving further. If it fails, moisture can condense in the air tanks and spread through the braking system, potentially freezing and causing blockages that impair braking.
An impaired braking system is a disaster waiting to happen. The good news? You can greatly reduce the risk of freezing and blockages by following these six simple steps that help keep moisture out and clean, dry air in.
6 Steps to Winterize Vehicle Air Lines
1. Check the Discharge Lines and Air Lines
Ensure discharge lines slope downward from the compressor discharge port with no water traps, kinks, or restrictions. Lines should not droop, as it can create water traps that can freeze.
Insulate the last three feet of the discharge line — including the fitting at the end — with ½-inch-thick closed-cell polyethylene pipe insulation to retain heat and reduce the risk of freezing.
For air lines, cold temperatures make rubber less flexible. Inspect for cracks, leaks, or brittle hoses and replace them immediately. Make sure gladhand seals are clean, dry, and tight, and use gladhand covers when parked. Avoid kinks or sagging lines that can trap moisture.
2. Stay on Top of Air Dryer Maintenance
A faulty air dryer is one of the top causes of frozen air systems. Regular inspection and maintenance are crucial to preventing moisture from entering. Check that it’s working correctly by:
- Inspecting for air leaks and dryer cartridge damage
- Ensuring the purge valve, governor, and air dryer heater are working
- Checking delivery lines for blockages
- Examining the desiccant cartridge for saturation
- Making sure valves function correctly and the air compressor builds adequate pressure
- Replacing the air dryer/desiccant cartridge once a year — ideally in the fall
3. Drain the Air Tanks
For clean, dry air, the air tanks need to be drained regularly. Moisture collects in air tanks, and if left there, it can freeze and block airflow.
One draining method is for drivers to drain each tank at the end of their shift and after shutting off the engine. Another is for drivers to open the drain cocks on all tanks and leave them open overnight to allow air and contaminants to escape.
Automatic drain valves are another option, and remove the driver from the draining process. Just make sure to check they are working properly before cold weather sets in.
4. Use Antifreeze
Air brake antifreeze lowers the freezing point of moisture, helping prevent ice formation in the air lines. Add it through the supply/emergency gladhand, not directly into the tanks. And don’t overuse. Excessive amounts can damage rubber seals.
Always consult the vehicle manufacturer or a mechanic for the correct antifreeze type.
5. Warm Up the System and Cycle the Brakes
Warming up the system keeps air moving, which helps push out condensation before it freezes and confirms system readiness before leaving the yard. Before moving, let the air pressure build to full operating range. Then press and release the brakes to:
- Free up sluggish valves
- Ensure proper brake balance
- Prevent sticking brakes
- Evaporate surface moisture and reduce freezing risk
6. Park Strategically
Where and how drivers park in winter can make a big difference. When parking for extended periods, drivers should look for a location with minimal exposure to the elements. Parking in snow, slush, or puddles raises the possibility of moisture splashing up that can collect on:
- Air lines
- Valves
- Gladhands
- Brake chambers
When temperatures drop, moisture can freeze and block airflow, locking the brakes. The best place to park is on dry, hard surfaces (asphalt, concrete, or gravel) where water can drain away. If it’s also a sunny spot and sheltered, well, that’s even better.
Winter will be here before you know it. Is your fleet ready? Don’t wait for the first freeze to find out. For more tips, explore our blog on vehicle winterization prep activities to get ready for the next cold front.