Like Robert Mathis I to have a little concern regarding the 12V compressor in my 2007 Contessa.
When I raise the tag axle the compressor always comes on. It just started doing this this spring.
The main tanks are up to full pressure but it still comes on.
Any suggestions on what may be causing this would be appreciated.

It could be that the sudden purge of air to raise the tag is enough to signal the air compressor to start...mine does the same occasionally.

BTW, I'm the second owner of a 2008 Contessa.  I believe the air compressor sensor switch was plumbed incorrectly from the factory.  It cycled on and off far too often.  As it turned out, the pressure sensor switch was connected to the air compressor through a T.  The line going to the compressor from the storage tank has a check valve at the tank to prevent air escaping from the tank through the compressor pump.  The check valve is required and installed where it should have been.  All air compressors will eventually leak down.  I moved the sensor to another fitting on the storage tank and the compressor seldom ever comes on.  I'll be out for over a week this coming week, so I can tell just how often it runs during extended use.  Right now, it hasn't cycled once in over 24 hours that I heard.

Gil

My 2008 Contessa works the same way, everytime I lift the tag axle the compressor comes on.  I thought it was normal but, maybe not.  When the coach is parked and on auto air level in the sleep mode I may only hear the compressor turn on once in 24 hours.  Is that normal?

Marty Christensen
08 Contessa, Rome 42, 400 cat

Marty, I think yours is normal or the air compressor doesn't have enough wear to have any leak down.  Take a look at where the air pressure switch is mounted to be sure.

Gil