Frozen trailer air lines

Adding "air brake anti-freeze" is what you need and YES it will melt a blockage.

Don't use rubbing alcohol>it eats rubber components in valves.

If you have the supply disconnected and the trailer still moves check the brake chambers to see if they are "caged".

 

Try putting the alcohol in the service then hook it up and go in truck release brakes and pump the foot brake several times

 

Your grey hair (like mine) is showing.

 

i'm willing to bet the brakes have never been adjusted.

you can hear the trailer air up. if the line was frozen. you'd push the valve in and hear no air going into the trailer at all.

 

Wait till spring and then check those brakes!

 

Do like Ralph said and use air brake anti-freeze. Remove the glad hands from the trailer and fill the lines up the best you can and re-hook to the trailer. Then cycle your brake buttons a few times. You might have to repeat a couple times. Rubbing Alcohol will not only eat on seals it is made with mostly water. What happens when the alcohol evaporates? It sounds like the valve on the backside of the back tank that has about 6 lines hooked to it. But trying to decipher which valve it is redundant. Treat and thaw is your cure. Always carry a bottle of that stuff with you. You might even get it from your shop.

The other scenario is someone dropping a trailer with wet shoes that freeze to the drums. Then you get out there and beat with a hammer being careful to hit the drum flat from the back side. The vibration will crack the ice.