Atwood Furnace, Hydro Flame, Land Yacht Clipper

[masseyfarm]

Have been having a problem with my furnaces on the Clipper. They would both fire for about 7 sec. and the go into ignition lock out. (three flashes of the indicator lamp)
This happened after no use during the heat of summer season that changed suddenly to cool fall nights in the north of the 49th.
After blowing the units out with compressed air, and checking the grounds, inspecting the print board for solder cracks, etc., I determined that the main board connections were not getting good contact.
I cleaned the print board connection with emery paper, and also the wire harness plug metal contacts. I then pried up the metal barbs slightly in the plug to increase the contact friction.
The both furnaces worked great on reassembly and no hard earned cash was spent!!!!!
The process is one of elimination. Check the easy things first and progress on to the expensive parts. If you are at that point of almost buying a new print board because thats the last thing that can be wrong, then how much damage can you do? In my case the patience and observation paid off with NO BILL.
Good Luck
Dave

[Robfike]

Love it!

[masseyfarm]

Originally Posted by masseyfarm

Have been having a problem with my furnaces on the Clipper. They would both fire for about 7 sec. and the go into ignition lock out. (three flashes of the indicator lamp)
This happened after no use during the heat of summer season that changed suddenly to cool fall nights in the north of the 49th.
After blowing the units out with compressed air, and checking the grounds, inspecting the print board for solder cracks, etc., I determined that the main board connections were not getting good contact.
I cleaned the print board connection with emery paper, and also the wire harness plug metal contacts. I then pried up the metal barbs slightly in the plug to increase the contact friction.
The both furnaces worked great on reassembly and no hard earned cash was spent!!!!!
The process is one of elimination. Check the easy things first and progress on to the expensive parts. If you are at that point of almost buying a new print board because thats the last thing that can be wrong, then how much damage can you do? In my case the patience and observation paid off with NO BILL.
Good Luck
Dave

Update:
PROPANE IS HIGHLY FLAMMABLE. IF YOU ARE NOT QUALIFIED TO MAKE THESE REPAIRS, THEN IT MAY BE SAFER AND CHEAPER IN THE LONG RUN TO HIRE A QUALIFIED TRADES PERSON!

TURN OFF THE PROPANE and run the stove to clear the lines of pressure.

The Atwood furnaces installed in the Clipper are 8531 III DCLP and are rated at 31000 BTU. Servicing of these units should be done annually.
Open the access door and loosen the wing nut holding the exhaust pipe. Wiggle the exhaust pipe and pull straight out. Remove 3 metal screws from the rear of the compartment with a long extension on a small ¼“ socket nut drive set and another similar metal screw, located on the center front of the lower fan shroud. Remove the propane connection and cover the pipe end fitting to avoid getting dirt in the line. Pull and gently wiggle out the burner unit and check the electrodes. 1/8” should be the distance between the hot and the ground/sensor units. Clean all electrical fittings. Blow out all areas to ensue no blockages in the heat exchanger area. (be sure to cover the propane pipe so no dirt will get into it) Reinstall the burner unit with all wiring attached and secure with the 3 metal screws at the base and also the one in upper front in the fan shroud. Reconnect the propane fitting. Clean the base of the exhaust pipe with a wire brush and apply a small amount of anti-seize. Start the wing nut ( easier to start the wingnut now as space is limited after you get the exhaust pipe in) and install the exhaust pipe and then tighten the wing nut. Turn on the propane and test the fitting connection with soap and water to insure that there are no leaks. Turn on the thermostat to test the furnace operation.

See the Atwood manual for trouble shooting, if further information is required.

Pay close attention to the connections for the flame sensor, as this seems to be a consistant problem on these units. As mentioned above, the main plug must have good contact with the board.
As can be seen in picture # 4 the burner was in poor condition and was replaced. Part #32811.

Motor Replacement.

The motor in this unit has no service points on it other than ensuring the connections are clean and tight. Only abnormal noise indicating bushing life has expired will nictitate the motor replacement.These motors use brass bushings not bearings, and that is where any problem will show up as noise. Usually an auwfull noise as time goes by.
The motor can be replaced without pulling the furnace and is readily available online, if not locally.
From outside access door, on the left or top, will be the pc board, a wing nut holds it in, remove board and unhook wires. Next on the right is the exhaust, loosen wing nut and pull exhaust tube out. The black cover over the main blower assembly, four screws, swing the cover out and up. A long allen wrenchis required to loosen the set screw and remove blower wheel. On the right you have the small combustion wheel, loosen the set screw on it. A strap holds the motor secure, remove set screw and remove motor. Always take care to clean any area with the airgun, and try to wirebrush any wire terminal connections while you have the area open.

[masseyfarm]

Since previous furnace service I have experienced continued problems on the rear furnace of the CLIPPER with the fire shutting down early, then not able to maintain burn, and finally would not fire.
I changed the print board with no results. Pulled the burner assembly and checker the gas valves for operation, the igniter wire for continuity, and cleaned and reconnected all leads and grounds.
Finally I checked the sail switch, and found it dead. Took it apart to see what was in there and discovered lots of stuff colored a nice emerald green.
I hope to source a new combustion sail switch tomorrow and expect the problem to be solved. I will confirm when up and running.

COMBUSTION SAIL SWITCH is accessed without removing the furnace. Just open the access panel and remove the 4 sheet metal 1/4 cap screws that hold the plastic (ABS) cover on the motor housing. The sail switch is attached to this cover with 2 screws.
Lots of good info on this link.
Troubleshooting the RV Furnace
Dave

Sail switch

The sail switch is an on/off device. (normally in the off position) It gets it's name from the "sail" or paddle that is attached to the switch mechanism. As the blower comes up to speed, it blows air onto the sail with enough force to push the switch closed, thus allowing electrical current to flow to the next component in line.
It's job is to determine if there is adequate air flow for proper combustion to take place. If the battery voltage is low or the fan does not come up to 75 per cent of it's design speed, the sail switch will not close.
Possible causes of this malfunction are: low battery, restricted return air inflow, restricted or inadequate outlet vents, restricted combustion air inlet or exhaust, faulty sail switch.

[masseyfarm]

Repair done for less than $25.00
Installed the new Combustion Sail Switch today Atwood #35030, available locally, cheaper than on line with the shipping. Good stock at Big Boys Toys in Parksville. Big Boy
Took 20 min. to install and test.
Ready for the road.
Dave

[masseyfarm]

We are on the road and again had a problem with the rear Atwood 8531- III furnace not firing. We had travelled through the Rockies and had some salt exposure on the high mountain Rogers Pass. When I inspected the furnace and tested the sail switch for continuity, I found that the terminals were corroded and not making contact. The female terminals are located upright so as to trap moisture inside. I was able to clean with a small file and everything works as it should.
If the furnace runs, but does not fire, and you can not hear it trying to ignite, then the sail switch is your first area to check with a digital resistance tester.
Dave

[masseyfarm]

Applies to the Clipper but may be relevant to many other models.

The Clipper is equipped with two roof mounted low profile 15000 BTU Duo-Therm Penquin Air Conditioners c/w heat stripes for cold weather operation and a fan only option to keep the air moving during those poker games.

These units, along with the two basement mounted Dometic 35000 BTU furnaces are electronically controlled by a 4 button DuoTherm thermostat that is wall mounted to the rear of the dinning area.
This 4 button thermostat tends to act up over time and is no longer available to purchase from any OEM.

DuoTherm 4 button controls can be rebuilt provided the LCD and the computer chip are not damaged and these services are offered by Dinosaur Electronics and others as found on Ebay and other sites.

One of the problems that show up with this thermostat unit is - the on/off switch solder contacts become loose from the print board with rough handling.

Only if you are having problems with intermittent power, and you have checked the security of the phone style cable that connects this unit with the operating system, and you have power at the thermostat, should you proceed to this next step.

Remove the thermostat and carefully inspect with a magnifier, the solder joints that hold the switch to the board. If there is movement at the joints, they will have to be carefully re soldered.

Another problem may appear as the unit ages and is exposed to damp cooking air or a smoky environment.

The contacts under the buttons are unresponsive when the button is depressed.

This problem may be a little more involved as there are many small spring mounted parts under the buttons that tend to fly away never to be seen again when released.

For this attempted repair, with the unit exposed, try first to use a contact spray cleaner and work the button numerous times to clear the contact surface.

If this does not solve the problem you might want to contact one of the re builders now before you damage, of loose parts, that will disqualify your core unit from exchange.

However, if you decide to proceed to taking the button out, use extreme caution, as it is spring loaded, and those 3 little parts under each button disappear very quickly.

Many times, with a little effort and time, the life of these devices may be extended.

Always handle with care and try not to use spray wax or harsh cleaners, candles etc in the area of the thermostat.

Dave