Dew point reading shows 80°F and never drops:

 

The upper range of the sensor is +80°F.  If that value is displayed, it likely indicates the presence of moisture in the sample tubing or on the dew point sensor tip.  If this moisture is not removed, it will cause the sensor tip to corrode and will eventually require the sensor to be replaced.

 

First, check the dew point sensor tip for obvious signs of moisture, corrosion, and/or damage causing high readings.  Loosen the plastic compression fitting that holds the dew point sensor.  Pull out the sensor and visually inspect the region of the probe normally inserted into the sample block.  An example of sensor damage due to prolonged exposure to excessive moisture is shown below.

 

  

Figure 4

 

DO NOT ATTEMPT TO REMOVE THE MOISTURE FROM THE SENSOR WITH A CLOTH OR COMPRESSED AIR AS THIS CAN PERMANENTLY DAMAGE THE SENSOR.  There are a few ways listed here to remove the moisture from the sampling lines and Simple Dew analyzer.  The method used will depend on how much time the user can afford to be without measurements from the Simple Dew analyzer.