Atwood heater failure - need advise!

Comments still coming in. Awesome, and thanks for the additionals. As the weather was crappy, I didn't get to it this weekend. And then it went into storage for a couple of weeks. I will be working this issue upon my return to hopefully-sunny SoCal. As always, I'll post when I find the issue. Peace.

I have found bad connections at the slip on wire connector to the board. A loose connector to the board can sure cause some intermittent operations.

John&Joey wrote:

dougrainer wrote:

Weldon wrote:
When my furnace failed to operate the problem was lint on the orfice.
Between the info here on RV.Net and what I could find in the manual,I knew to look for lint. It was so small I did not think that was the problem, but it was.

But it would still attempt to light,(ignitor and gas valve clicking on). The OP does not have that happening. Doug

I can't speak for the OP, but my hearing is such that I may not be able to hear things that others can, which would lead me into assuming things.

The OP stated he heard NOTHING coming from the furnace other than the fan running. As to hearing, THAT IS a requirement for accurately diagnosing something. Doug

dougrainer wrote:

Weldon wrote:
When my furnace failed to operate the problem was lint on the orfice.
Between the info here on RV.Net and what I could find in the manual,I knew to look for lint. It was so small I did not think that was the problem, but it was.

But it would still attempt to light,(ignitor and gas valve clicking on). The OP does not have that happening. Doug

I can't speak for the OP, but my hearing is such that I may not be able to hear things that others can, which would lead me into assuming things.

Weldon wrote:
When my furnace failed to operate the problem was lint on the orfice.
Between the info here on RV.Net and what I could find in the manual,I knew to look for lint. It was so small I did not think that was the problem, but it was.

But it would still attempt to light,(ignitor and gas valve clicking on). The OP does not have that happening. Doug

When my furnace failed to operate the problem was lint on the orfice.
Between the info here on RV.Net and what I could find in the manual,I knew to look for lint. It was so small I did not think that was the problem, but it was.

Most good honest RV shops will test your board for free and tell you if it's good or bad.

A couple of years ago while on the road using my meter and the Atwood manual I determine that the board in my water heater was bad. $80 Dinosaur board from A.S.A.P CLICKY (great to work with, FedEx overnight to a drop site even) and it fired right up with never a problem afterwards.

ON EDIT:

Just verify that the tank valve isn't tripped by lighting the stove.

wa8yxm wrote:
You may find this helpful... Note to others.. I typed this from memory the first time (Finally saved it to HD) if you find any errors or omissions, please call them to my attention so I can fix it. Thank you.

When the T-Stat calls for heat the control board starts the blower (1)
The blower blows closing the sail switch (2)
The control board then opens the gas valve (3) and begins sparking (4.1)
Gas Flows (5) And ignights (4.2)
The flame heats the flame sensor (5)
The flame sensor sends .480 volts to the control board (6)
which then detects the .480 and continues operation (*)
When the T-stat says "Enough already" (RV is now warm)
The control board shuts off the gas flow (*)
and then turns off the blower after a cool down (*)

*: At nearly every step the control board is invovled. IF IT IS BAD, things will not work.. I recommend replacement boards from Dinosaur boards.. When Mine went out the Dino board was less than half the price and when opened the box the quality of construction and workmanship, and then design was very clear to my trained eyes.

1: No 12 volt to furnace, blower motor shot
2: Low 12 volt, air ducts clogged, blower "obstructed" bad sail switch
3: Bad solenoid
4: .1: Bad ignition curcuit (high voltage) on control board. .2: Points too wide (Very common it seems)
5: These do not often fail but they can
5: Bad connection, NOTE:
5 and * Bad wire.

* applies to all steps nby the way So does bad wire/connection.

You MISSED the most important part. AFTER the 12 volts flows from the sail switch it goes THRU the Hi Limit switch. IF the Hi limit is bad(open) NOTHING happens. Main Control boards rarely fail anymore. Regardless of what some think. I cannot remember the last time I replaced a control board on a Furnace/Water-Heater-Refer. I HAVE replaced various control parts on these appliances, but rarely a control board. Doug

You may find this helpful... Note to others.. I typed this from memory the first time (Finally saved it to HD) if you find any errors or omissions, please call them to my attention so I can fix it. Thank you.

When the T-Stat calls for heat the control board starts the blower (1)
The blower blows closing the sail switch (2)
The control board then opens the gas valve (3) and begins sparking (4.1)
Gas Flows (5) And ignights (4.2)
The flame heats the flame sensor (5)
The flame sensor sends .480 volts to the control board (6)
which then detects the .480 and continues operation (*)
When the T-stat says "Enough already" (RV is now warm)
The control board shuts off the gas flow (*)
and then turns off the blower after a cool down (*)

*: At nearly every step the control board is invovled. IF IT IS BAD, things will not work.. I recommend replacement boards from Dinosaur boards.. When Mine went out the Dino board was less than half the price and when opened the box the quality of construction and workmanship, and then design was very clear to my trained eyes.

1: No 12 volt to furnace, blower motor shot
2: Low 12 volt, air ducts clogged, blower "obstructed" bad sail switch
3: Bad solenoid
4: .1: Bad ignition curcuit (high voltage) on control board. .2: Points too wide (Very common it seems)
5: These do not often fail but they can
5: Bad connection, NOTE:
5 and * Bad wire.

* applies to all steps nby the way So does bad wire/connection.

Awesome information All!!! Thanks. I will be doing some troubleshooting in the morning, armed with this good stuff. Will keep you posted. BTW, space heater still has me comfy while typing this. hehehe Peace!