888.Fix.Tire 888.349.8473

Common Roadside Service Calls Part 2: Frozen Trailer Air Lines | Semi Truck Repair

air line antifreeze

Part two of our roadside service call series highlights another common occurrence in the winter months: frozen air lines. While many drivers won’t set trailer brakes at all when parking or employ little tricks to attempt to dry the shoes out before setting them, drivers picking up a dropped trailer or coming back to equipment that’s been sitting for a few days still might find the lines frozen.

Bendix notes that even a one degree change in temperature can cause condensation. (And that’s on top of the 4 to 6 ounces of water a commercial truck produces during the course of a normal day.) Couple that with winter temperatures and your lines can freeze up in under the amount of time it takes for you to have your federally mandated break.

Keep in mind that the air dryer in your brake system can only do so much.  Excessive idling in cold temperatures, discharge lines that are improperly installed, air leaks, or reservoirs that are not regularly drained can all lead to frozen lines.

As we mentioned in the last post on gel ups, preventative maintenance is the best way to save yourself the cost of a roadside service call or forced downtime in your fleets maintenance shop. We recommend changing the desiccant cartridge on your air dryer and checking the purge valve before freezing temperatures even arrive. If you remember a lot of moisture in your system at the end of the previous season, it might even be a good idea to swap out the dryer completely.

Additionally, (and this one is important,) even if you have automatic drain valves, we still recommend your drivers periodically purge the system of all air and drain the tanks manually during the winter months.

What to do if your lines are frozen and you need to get moving? We’ve heard many drivers speak about adding alcohol to their lines to unblock the lines and release the brakes. And while we’ve heard that this solution can be effective, it is not one that we recommend. Many solutions of rubbing alcohol actually contain water. So while the fix may be immediate, you may deal with more freeze up issues later once the alcohol has evaporated and the water from the solution is left behind.

Your best bet, and the one we will use if your driver isn’t prepared or unfamiliar with the system, is to keep a bottle or two of air line antifreeze in your truck. If you find your lines frozen, remove the glad hands and squirt some of the antifreeze into the lines. Replace the glad hands and cycle your brake buttons several times to work the fluid into the lines. You may need to repeat this process more than once to free the lines of ice and release the brakes.

If your brakes still won’t release, your shoes might be frozen the brake drums themselves. Use a hammer to tap lightly and break up the ice to release the brakes.

Back to top