Atwood MPD 31470

[dgwilson40]

I have a 2007 3500RL (just purchased) It has an atwood MPD 31470 that is hard to start. Once on, it will run until it reaches set tempature shuts down and then does not restart until it sits for a long time. Has anyone run into this with there furnance? Many Thanks, Greg

[lcarter]

We have the same problem. Several visits from the repair guys and a new thermostat still have the same problem. Please keep us informed.
LCarter

[stiles watson]

I have an Atwood furnace also. I don't know what you mean by "hard to start" and "set a long time". When it reaches temperature, it should shut off and not come back on until the temp drops a few degrees. If it shuts off and you raise the thermostat setting, it will not immediately come back on. There is a built in delay of a minute or so before it kicks in again. if it is offf and you turn it on there is a delay built in before it comes on. As a matter of fact, that is also true for my A/C unit.

The only problem I have had with mine is that the igniter wire developed a break in the insulation and shorted out so that the spark never got to the burn chamber (like a spark plug wire with a break and the spark shorts to the block). I replaced the igniter wire and it worked fine.

On the circuit board under the outside door, there is a LED light that has a code, slow blink, fast blink, three blinks, etc. with an interpretation printed. If you don't understand the error code. Call the service tech at Atwood. They can walk you through many issues. If there is no error code, perhaps it is operating properly or as designed.

[dgwilson40]

When I turn the thermostat to on I heat a click, the blower starts and then the burner fires for about 5 secs then shuts down, then the blower shuts down click and this repeats 3 times then all goes quite. I turn the thermostat off, wait about 10 secs then I turn it back on and the cycle repeats. About the third time it finally starts and stays on until the camper is heated up and then it shut downs. It doesn't come back on. So I power cycle the thermostat off, wait a few seconds turn it back on and then nothing. I wait about an hour go back out turn the thermostat on it does it's cycle and finally lites. Last night it actually was working great. I could raise and lower the thermostat up and down to get it to come on and off. To day it just does the 3 cycles and shuts off. Note: To get it to come on in the past I have had to turn on both propane bottles. WHen it was working last night I only had the one on. I even lite all 3 burners on the stove to see if there was a drop in flow. There did not appear to any.
Thank you for responding

[8.1al]

It sounds like the furnace is not sensing the flame so it shuts the gas off and after 3 tries it will stops. Turning the thermostat off resets this. Your thermocouple may not be properly positioned or may be defective

[stiles watson]

Go out and open it up. Have your wife operate it while you watch. Check to see what the LED light on the circuit board is doing. My guess is that you either have a bad circuit board or a bad igniter wire. Do call Atwood service tech. they are patient and very helpful. At least they were to me.

Are you sure the furnace is lighting and you really have fire in the chamber, i.e., heat coming out the register? From what you describe, it sounds like the firebox is not lighting and the furnace shuts down for safety. If you are watching this cycling from outside, also listen for snapping or popping and look for arching. The igniter wire is the red one.

[dgwilson40]

Thanks for your suggestions. The furnace I don't think has been used in quit a while. I got it to light up this afternoon and has been running for several hours just fine. It seems to take several tries to get it going. One of the problems I have is I would have to pull it to get to the electronics. The only exposed piece is the exhaust. The rest is under the stairwell to the left. I may pull it and check it connections and thermocoupler.
Greg

[dgwilson40]

Update on my furnace issue. After letting it run for a few hours a couple of days in a row. It is working properly. Hopefully this has burned the cob webs out of it and will work well in the future. Thanks for your suggestions.

Happy Trails
Greg

[stiles watson]

Great! Bottom line is you got heat where you need it.