Check the air compressor for proper operation.

Refer to Air Compressor Diagnosis .

Check the line or hose for restrictions.

Repair ir replace the line.

Check the air brake valve.

Refer to Front Air Brake Limit Valve Operational Check .

Check for ice in the air system.

Refer to Air Dryer/Moisture Ejector System Check .

Check if the brakes are out of adjustment.

Refer to Air Drum Brake Adjustment .