Problems with Furnace

[Welder85]

Hi,
I am having issues with my furnace. I have look all over the internet trying to figure it out with no luck. The area I am in has no mobile RV repair men so I am on my own.

The furnace is a Atwood Hydro Flame 8900-III model 2540. This is in a 2010 HitchHicker.

The issue I am having is the heater will blow warm air out of the 2 living room vents, but it the rest of the vents in the camper it blows slightly warmed air. I do not believe any of the vents are blowing as warm or hard as they should be. Also the furnace fan seems to be louder than what it should be. It has kind of a vibration type noise. The heater seems to be working correctly besides the noise and lack of heat.

I have checked the propane buy turning the stove, furnace, and water heater all on at the same time. I could not tell a difference in the burners on the stove. I read to check that online. I checked the battery voltage while the heater was running, and the voltage held pretty constant at 13.5. I also checked and the squirrel cage fan blades and they are clean.

I appreciate any and all help and advice!

Thanks,
Welder85

[Welder85]

Thanks for the manual. The flow feels great on high, and the motor sounds like it should.

[Old-Biscuit]

HERE is manual that covers your model.
Pg. 13------wiring schematic
Pg. 15------t-stat operation
Pg. 17------Furnace sequence
Pg. 45------exploded view

Noisy fan..low air flow------loose fan, dirty, obstructed supply/return, obstructed intake/exhaust, loose/disconnected ducts

When you have furnace fan on High Speed.....how is air flow thru ducts?

Low Speed may not move enough air to 'fill ducts' as they need to be sized for High Speed Operation.

[Welder85]

Thanks for the fast replies!
Air inlet is clear nothing in it, and all the duct work is connected.

I noticed something weird. When I turn it on to heat and makes noise and hardly blows, but I can switch it over to fan setting and it blows hard and the fan sounds good. No odd noises or nothing and plenty of air coming out all the vents. I guess the fan has a high and low speed, but I don't understand how only the low speed is messing up?

[rrupert]

Have you checked to see if any of the ducting is disconnected, clogged, crushed or damaged? Mice like to build nests in duct-work.

[joegray]

Check the air inlet to the furnace. Bee's and other bugs like to build nests in the inlet vents.