Head Relief Function

Prior to every activation of the compressor motor, the height sensor closes switch A and C, energizing the exhaust solenoid for approximately 1 second to relieve the pressure in the compressor head. This prevents the compressor from trying to start against a high head pressure, drawing a high current, and potentially stalling and blowing the ELC/TRAILER and/or PWR QTR VENT fuse. This cycle is controlled by the height sensor and will not occur if the sensor is already in the exhaust mode (sensor arm below the in-trim zone).