Odd brake problem.

ICE in Air Lines??

 

You’ve got a possible trailer brake valve issue or if it’s frozen due to cold temps.

Or an airline that’s kinked or collapsed internally not allowing the pressure to release so the valve can release the brakes.

 

S-cams binding from bad bushings ?

 

Wasnt there an air can recall on a ton of chambers a few years ago?

 

Sounds like a reoccurring problem so maybe not ice? When they are dragging set the tractor park valve and leave the trailer released. Remove a service side air line from a brake chamber, that is the one closest to the slack adjuster. Was there air on it? Did the brakes relax? If so it is a valve, restriction or ice problem as mentioned.
It that was not it remove clevis pins from a slack adjuster that has pressure on it. That is easier said than done. Clevis pins could be the problem themselves.
With vise grips on the s cam can it turned back and forth?

 

Yes there is a return spring in the chambers. If that other stuff is good they may be week.

 

Brake pedal sticking down ??

 

How much grease do you put in the s-cam tubes?
Years ago I was first told, only a couple of pumps, you don’t want excess grease getting into the drums.
Wrong. You pump in the grease until it comes out the slack end of the tube. The seal on the other end keeps the grease from getting into the drum.
Not enough grease can cause two issues: worn s-cam bushings that then let excess grease bypass the seal so the grease gets into the drums; and stiff, sticking s-cams that operate as you described.

Just a possibility, could be an air valve problem too.