coach heater flapper door?

hello, i am in the process of replacing the coach heater fan in our 2003 winnebago 35 and was wondering if anyone knows the exact location of the "flapper" door so i can check it before putting this mess back together? thanks
dennis

"Flapper Door"?  Never heard of such a thing.  Sail Switch on the house or air doors on a dash yes. but "Flapper Door"?  on the exhaust fan over the stove is where you find one of those.

hello, when i was trying to diagnose the problem of a seized coach heater fan, i read that apparently there is a flapper door somewhere in the ductwork near the coach heater that allows the heat from the heater to blow throughout the floor ducts when the coach heater fan switch on the dash is turned on, then closes when the furnace blower is operating so that the furnace heat can utilize the same ductwork?
i disassembled the coach heater core to replace the blower motor but it was a real nightmare getting it apart and i want to check this flapper to make sure it is working before i put it all back together but i cannot seem to locate it so i was wondering if anyone can narrow down it's location?

Never heard of such a thing for the house propane furnace. The vehicle HVAC system that feeds the dash area outlets usually has a flapper door that gates air flow to dash vents vs defroster vs the under dash floor-level heater, but that has nothing to do with the hosue furnace and house ducting.

Maybe someone with more Winnebago experience can help if there is such a thing.

Thanks Gary if you have never heard of it, and I have never heard of it.. Well. 

Normally dash heat systems are 100% independent of house systems.

My guess is that mrd341 misinterpreted what he saw/read somewhere.  The "floor" duct/vent in the vehicle HVAC system is simply the floor-level outlet(s) somewhere under the dash.  My last coach had three of those, a large central one and a smaller one angled to either side to keep driver and passenger feet warmer.  I doubt if there is any connection to the house heat ducting.

hello, while researching  this new to me 2003 winnebago adventurer 35u, i found that a common problem with these units is that the "REAR coach heater fan" sometimes starts making a loud squealing noise when the fan is turned on with the clearly marked "rear coach heater" high/off/low switch on the dash. the switch controls an entirely separate heating system for the rear of the coach that runs off the engine cooling/heating system to warm the rear of the coach while driving,(similar to the one in the hot water tank). this rear coach heater system has it's own heater core and blower, that is situated in the water pump compartment right behind the hot water tank and is nearly impossible to work on without removing the hot water tank. Although it is separate from the dash heat and the furnace heat, it utilizes the furnace ductwork to distribute the heat from the floor vents by the use of a "flapper" type door somewhere within the ductwork that only allows the air to flow from the coach heater when the furnace blower is not running, kind of like a one way valve, if i am understanding it correctly. when this "coach heater" blower with a squirrel cage type fan starts to seize up, it makes a squealing noise and pops the backup camera fuse,which is apparently a common problem in these workhorse units. after much yelling and cursing, i got the blower motor out without removing the hwt and am ready to re-install a new blower motor into the heater core but i wanted to check this "flapper door" that i read about before i do and am trying to find out how to get to it before i put this all back together, so i was wondering if anyone has gone through this before? ( i guess a lot of people just disconnect the switch and do not use the rear heater instead of going through all of this to get at the thing, but i decided to try and repair it) thanks

after much searching, i found the approximately 12"x 7" flapper door within the ductwork in between the floor vent that is between the two front seats (directly behind the doghouse) and the rear coach heater blower directly under the folding table behind the front passenger seat! i was able to get my hand in the duct and flip it open and closed so it is working properly, now i can try installing this nightmare of a blower motor blower! thanks

I got me an edujumacation ;D

i've been a backyard mechanic for most of my life and this has been "without a doubt" the most difficult task that i've encountered to date! although i've heard that these blowers have a history of failing, they were definitely not installed with the intention of being removed, ever!!!!

mrd341 said:

i've been a backyard mechanic for most of my life and this has been "without a doubt" the most difficult task that i've encountered to date! although i've heard that these blowers have a history of failing, they were definitely not installed with the intention of being removed, ever!!!!

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Unfortunately, My 2001 35U is blowing the fuse when I turn the switch on. Looks like I'll be cussing a bit trying to fix this blower! I know this is an old post but if you are still on here, I would take any suggestions for an easier fix on my end! Thanks

Dickthemooner said:

Unfortunately, My 2001 35U is blowing the fuse when I turn the switch on. Looks like I'll be cussing a bit trying to fix this blower! I know this is an old post but if you are still on here, I would take any suggestions for an easier fix on my end! Thanks

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As it's the case for a lot of threads, the OP hasn't been around since 03/2019.

If the unit keeps blowing the fuse, it may have a physical obstruction (e.g. A wasp nest, dust or other debris) blocking the fan and causing the overload.

Other issues like wiring continuity (e.g., exposed wires touching metal) can cause this as well.

mrd341 said:

hello, i am in the process of replacing the coach heater fan in our 2003 winnebago 35 and was wondering if anyone knows the exact location of the "flapper" door so i can check it before putting this mess back together? thanks
dennis

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The only "Flapper Door" I know of in the House part of an RV is the vent flapper on the range hood. Usually a pair of dogs (Twist thingies outside under the vent hood secure it closed. Some have a device inside under the hood. (Often on the right side as you face it,.
The only other "Flapper doors" are in the dash HEVAC system directing air flow. not in the "House" part.

uchu said:

As it's the case for a lot of threads, the OP hasn't been around since 03/2019.

If the unit keeps blowing the fuse, it may have a physical obstruction (e.g. A wasp nest, dust or other debris) blocking the fan and causing the overload.

Other issues like wiring continuity (e.g., exposed wires touching metal) can cause this as well.

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Thanks for the reply, I figured I wouldn't get an answer but it never hurts to try. I am assuming the blower fan is the one he mentioned behind the water heater. Lucky for me I'm an old mechanic and can work on most anything. I'll need to crawl in that area best I can and look for obstructions. Sucks you really can't see it, as he mentioned. Thanks again for replying to my post!

This ought to help:

Water Heater Removal and Coach Heater Repair

And to the original 4 year old question about the flapper door, which the OP said he found in post #8.

There's actually a flapper door at both ends of the heater ducting in the floors of Winnebago Class As that have the propane heater at the rear and auxiliary heater up front. They are check valves that allow the two heat sources once way access to the common duct in the floor.

ennored said:

This ought to help:

Water Heater Removal and Coach Heater Repair

And to the original 4 year old question about the flapper door, which the OP said he found in post #8.

There's actually a flapper door at both ends of the heater ducting in the floors of Winnebago Class As that have the propane heater at the rear and auxiliary heater up front. They are check valves that allow the two heat sources once way access to the common duct in the floor.

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Thanks for this! When I get time in one place, I'll attempt the repair. Its not really that I need it right now, I just don't like it when crap don't work. lol