No electric to some components

[Lawrence Tarnoff]

Our coach has been in heated winter storage for about six weeks.  I visited today to run the generator, which started quickly.  I planned to run the roof heat pumps to give the generator a load, but got no response when I turned on the thermostat.  By no response I mean no readouts lit.  I also had no 12-volt lights.  The welcome light/message on the microwave illuminated, but the refrigerator would not start.  Thoughts?

Thanks,

Larry

[Mike Groves]

My immediate thought is "salesman switch" inadvertently hit on the way into the coach if applicable to yours.  Second is the coach battery disconnect.

Mike

[Lawrence Tarnoff]

Thanks.  I turned on both disconnect switches when I arrived at the coach.  And I toggled the salesman switch a couple of time to no avail.

[Steve Huber Co-Admin]

Larry,
Sounds like you've lost 12v power. Reefer needs 12V as well as 120v AC. I'd check house battery voltage first. Then check voltage on each side of "salesman switch" relay. Should be located in/near battery compartment. You should always have 12+v on one of the large studs. When throwing the salesman switch you should see 12v on both studs. Check twice, once as is and once after pushing the salesman switch once. If no voltage on one of the studs, relay is probably bad. Only other check would be to verify you have 12 volts on one of the smaller wire terminals of the relay when the salesman switch is in one of its positions. This signal activates the relay. If no voltage here, probably a bad salesman switch.
Steve

[Joel Ashley]

People overuse the salesman's switch and it wears out.  It should be left on all the time.  We are often just too lazy to go back, lift the big battery bay door, and do the correct thing by turning off the house Main.  Either the switch at the entry or its solenoid/relay in the battery/big fuse area gets worn out and fails, leaving the symptoms you describe.

Check your coach battery connections for integrity of course.  As Steve mentions, the refrigerator needs 12v to run even though we think of it as just alternating current and gas powered.  The reason is that the fridge's display, if any, and the board that controls everything on it is 12 volt.  It won't start or run on gas or 110v without that 12v control.

-Joel

God Speed, John Glenn

[Lawrence Tarnoff]

Thanks.  One follow up: does the thermostat run off 12 volt?

[Joel Ashley]

Yes, since you can run the hydronic heat on gas even when not plugged in to 110 power.

Joel