Hidden Noise in the Dash

[Gary Winzenburger]

After bringing our 1997 Marquis home from storage, I've had a noise somewhere in the dash that I don't know what it is, or where it's coming from. It sounds like some sort of fan motor, but I don't have anything turned on. The dash heater and defroster fan switches are off, as well as the front, floor heater. The only button that will shut it off is the "coach power switch" located just inside the front door next to the patio and ceiling light switches. Even after taking the nose access panel off, I can't locate it. Any thoughts as to what it might be?
Thanks!
Gary

[David T. Richelderfer]

uhhhhhhhh...  Hydraulic pump for the slides/leveling?  But that's 110v, I think.  How about the CD player for either music or navigation attached to the Kenwood/Silverleaf?  Or the DVD player attached to the Bose/Surround Sound or attached to the front TV for movies?

[Edward Buker]

Sometimes there is a small muffin fan built in to cool the electronics but I am not sure where it would be located in your coach. There is also a heater fan in the baseboard under the center console for the hydronic system.

Later Ed

[Steve Jewell]

Gary
       Do what we do. Go find a small child with good ears and they will point right too it.

Steve J

[Gary Winzenburger]

Still haven't found it, but still looking and thanks for the suggestions! Weird!

[Joel Ashley]

Not sure of the totality of what that "Salesman's switch" covers, but I know it's generally 12v. interior house stuff, and probably controls the feed to that fuse box.  A good deal of what's under the dash is chassis-related, nevertheless that switch affects your noise;  it follows that you might narrow things down by pulling fuses from the house 12v. box until the noise stops.  Failing that, I'd start pulling chassis fuses or disconnecting circuit breakers in the electrical bay one at a time.

You may not necessarily discover precisely where it is, but you should get a good idea of what it is, which should help lead you to it.

Joel

[Gary Nash]

97 Marquis c12
I have the same problem.  I think it is  caused by a motor that controls the air & heat baffles. I put a wire disconnect in a wire close to a micro switch that controls the baffle motor.  The problem was solved for over 6 years until this week. Just got home yesterday with a similar problem. When I turn on the ignition I hear the same sound for about fifteen seconds then it stops. Not sure, but I think it has to do with the ac and heater ballets.
Going gremlin hunting next week.
Gary

[Gerald Farris]

There is an electric vacuum pump that is mounted to the firewall by the evaporator case. It supplies the vacuum that operates the air control doors in the dash HVAC system. It should only run for a short time after the ignition is turned on unless you have a defective pump or a vacuum leak in the system.

Gerald

[Gary Winzenburger]

Gerald,
Does the vacuum pump also control the sliding platform over the entry steps?
Thanks,
Gary

[Edward Buker]

Gary,

Just to help out here....That sliding platform is run by an air driven reversing piston, so it runs off of compressed air from the main air tanks under the front of the coach. The air solenoid valve that operates it is in the main electrical compartment under the drivers seat behind the front outside compartment door.

Later Ed

[Gary Winzenburger]

Ok, thanks Ed, That's not it, so I'll keep looking. I'm taking it in for servicing soon, so I may have them look for it too. My hearing is less than good - too many load concerts in my earlier days!
Gary