Marquis Rear Hatch Fans

[Edward Buker]

I am currently in NM, and it has been well over 100 degrees here lately. I have never heard the rear fans on my engine compartment hatch fire up, and the engine maintains good cooling, even at high temps so they may never be active, if that is the thermostat source to activate them.  I would like to be able to fire up those fans for a couple of hours once stopped in a campground at the end of the day in this kind of heat.  Anyone know what fires up these fans?  Where does the wiring that feeds them comes from?  Has anyone added manual swiching from inside the coach?

Later Ed

[Gerald Farris]

 Ed,
I do not know how your fans are wired, however it sounds like you want your engine compartment fans to operate like the ones in some of the Marquis coaches with a 3208. In those coaches the fans come on with the ignition at start-up and run until 30 minutes after shutdown. There is a timer in the circuit that keeps the fan relay engaged for the extra 30 minutes after shutdown to cool-down the engine compartment.

Gerald

[LEAH DRAPER]

Wouldn't it be just adequate enough to just open the engine compartment?  Is it necessary to run fans alone.
What am I missing here guys?

Leah

[Gerald Farris]

Leah,
The reasoning for fans in the engine compartment is to purge the hot air to reduce the amount of engine heat that is transferred to the bedroom area. This was much more important before bedroom slides when the bed was on a platform that formed a box above the engine. In this design you had to lift the bed for engine access and the large opening between the engine and bed had no natural circulation to dispel the engine heat without a fan. Even on later model coaches, a fan will cool the engine compartment quicker if you are having a problem with bedroom heat after a day of driving.

Gerald  

[Tom and Pam Brown]

I agree with Ed.  I have never heard the large fan on the rear of the coach operate.  I am not sure if it works only if the engine reaches a certain temperature, or is it not working?

I would also love to have it come on when arriving. to evacuate the hot air from under the bed area, to assist in cooling the rear of the coach.

Anyone know how the fan is supposed to operate or when?

[David Fischer]

I have a 97 Marquis with a Gillig chassis and a C12 engine with an exhaust fan which is right on the louvers of the engine access door.  Over the years I have had to replace the fan twice as it gets a lot of use.  You should have a breaker in the electrical bay.  I just replaced mine. and it is available at any auto supply store. and not real expensive.  

[Edward Buker]

Seems like we have a bit of a mystery here as to how these fans are supposed to operate, and what the activating circuitry looks like.

 As far as having the fans operate like in an older 3208 coach, being on with the ignition and timed at shut down, I would prefer to only have them operate once I have pulled in and shut down, and really see no need to operate them while driving. No need for the extra alternator demand. The engine compartment sheds heat well while traveling.

As far as opening the engine hatch, I do that from time to time, but I do not like to leave it open when I am not around, nor risk forgetting to latch it back up, if it was a short stop somewhere. As Gerald noted forced exhausting of the engine compartment air would cool things more quickly and effectively. Every bit of heat shedding would help when in full sun and over 100 degrees outside, like it has been in the Carlsbad, NM area, for the last week. Air conditioning inside the coach cools to some extent, but it is no ice box in here...

If anyone has a schematic that has the fan system on it, I would be happy to see how it is supposed to work, and suggest a change to either manually power them up as needed, or automate a circuit that runs for some period of time after shut down as needed. I have the AC schematic from Gerald for a 2000 Marquis but have not come across a DC schematic yet.

later Ed

[Jeremy Parrett]

Our 2000 Marquis Amethyst does not seem to have these fans installed. After a long run we open the engine access door and all the bedroom cupboards. The coach cools down in a couple of hours.

[LarryNCarolynShirk]

My fans were added by Beaver Coach Sales when I bought it in 2003.  They wired the fans to come on anytime the ignition is on.  I suppose I could just add manual switch in the line somewhere.
Larry