according to the 393-02 series (not sure but the 392 may be the same) but the brake system uses a brake valve operated by 2 switches. One of those may have been stuck or it could just be out of adjustment just enough to cause an intermittant problem.
I thought it may have been frozen up but 40deg isn't enough to freeze it up.
Plus Linde is fairly adement on having heaters located near switches to keep that from happening. (not all trucks have heaters but quite a few do).
I would double check those switches adjustments, make sure they are not dirty.
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