Atwood Hydro Flame furnace shoots cold air then shuts off

[StarcraftNick]

i am very new to the RV world. I have a 2015 starcraft ar-one that I just bought used. I got the RV winterized last friday and on saturday went up to the in-laws for a big party they throw every year. i was only planning on using the furnace to stay warm through the night. we used a converter to hook the 30v up to a normal outlet (15v). The heat worked great for most of the night and then shut off. When attempting to turn thermostat off and back on again. the fan starts to run, but shoots out cold air for about 30 seconds to a minute then shuts off. propane tank is full. i tested the burners on the stove and they seem to be working fine. the flames are blue with an occaional yellow flair. i also tried at home where i have a 30v plug. It looks as if the former owner replaced the propane regulator once or maybe moved it. Any ideas on how to fix it. could it be something with the winterizing? since it is a hydro flame...

[bobndot]

Could be the circuit board. I had to replace a few of them, same symptoms as the OP.

[TKW]

A 3 y.o. sail switch could fail. Mine did.

We bought a new-to-me TT last spring and its furnace had similar symptom as yours except only intermittently. After some brain-storming with a knowledgeable forum member, we pointed our finger on the sail switch. Since I inherited an extended warranty from the previous owner, I took it to a RV shop. The 1st thing the RV Tech did was to test the propane pressure. The reading was 8" W.C. instead of the normal 11" W.C. A new propane regulator was installed and it worked for a few days but only when the furnace felt like it. On the 2nd pit stop, the RV Tech replaced the sail switch which had a short internally.
So you can see there are the two prime suspects that could cause your problem.

Another possibility is a failed main control board. My last TT has a Atwood Furnace. Its circuit board failed just barely out of warranty. The symptom was similar. The fan would start when the thermostat calls for heat. But the spark module wouldn't produce a spark, after 3 tries, the furnace would shut down.
You can rule this out by listening for some clicking sound during the starting cycle. If there's clicking sound, chances are the spark module is working.

[westend]

Do you have a hand held meter?

To check propane line pressure, you can make a DIY manometer with a piece of clear tubing. DIY manometer

[StarcraftNick]

So I hooked up the battery and it is still doing the same thing. I also ran the stove top for a bit to see if i could clean any air out of the lines. When the stove was burning there were flashes of yellow flame. is that a sign of bad regulator? the model number is 7920-. taking a look at the manual now online. thanks.

[winniman]

I would not suspect a sail switch in a three year old unit, although it is possible. If you have electricity available, having a 120 volt heater on hand can be useful if you run out of propane. Are you sure you have lots of propane. It will only run a handful of nights on full tanks. As stated, I would make sure you have a battery in the unit if you are using it. What if the power went off for a few hours. As stated your electric brakes require the battery for emergency stopping. My thermostat screwed up on my one mh, and would start the fan but not light the furnace. There again,not likely on such a new unit, but another possibility. Good luck. Let us know what you find.

[falconbrother]

StarcraftNick wrote:
I have already fired up the burners and let them run for about a minute. How long do you suggest I let them run for? thanks.

In our old motorhome we found that if there was air in the line it would do this, even in the middle of the night. It just can't maintain a good flame but, the fan would run and blow cold air, which sucks. Once all the air was out of the lines it worked perfectly. I would run the water heater and stove for a couple of minutes to get the air out of the lines.

[falconbrother]

This reminds me.. We always camp for two weeks through Christmas/New Years.. This is a new TT that we have never stayed in in the winter. I need to test the heat this weekend. Thanks!!

[Steve_83406]

westend wrote:
A service manual and troubleshooting chart is available from Bryant RV.

Bryant RV service manuals

This is excellent advice. Download the 58 page 2004 Atwood Furnace Service Manual and read it. It will show you how your furnace works, and has diagnostic sections that are very useful. Like others, I would check the sail switch. It isn't easy to get to, it is behind the large blower wheel on your furnace. If it needs replacement, it must be replaced with one specific to the model furnace you have. I'm not sure that the lack of a battery is the problem; if your converter puts out a solid 12V, the furnace should operate (and since the blower does turn on, it's probably okay).

Steve

[Atlee]

2 things. I'm not sure I understand correctly. Do you or do you not have a good 12V battery on the trailer? If you do not, how did you get the trailer to your in-laws? It's illegal to tow a trailer without a battery. The battery supplies power to the emergency brakes on the trailer.

Lack of battery could be the problem, however, most likely the problem is the sail switch. The furnace fan comes on first. It pushes cold air across the heater flues. It then goes across a switch reacts to the air. If there is air, the switch allows the furnace to cut on and supply heated air. If the sail switch doesn't detect air, it will shut down the furnace.

StarcraftNick wrote:
i am very new to the RV world. I have a 2015 starcraft ar-one that I just bought used. I got the RV winterized last friday and on saturday went up to the in-laws for a big party they throw every year. i was only planning on using the furnace to stay warm through the night. we used a converter to hook the 30v up to a normal outlet (15v). The heat worked great for most of the night and then shut off. When attempting to turn thermostat off and back on again. the fan starts to run, but shoots out cold air for about 30 seconds to a minute then shuts off. propane tank is full. i tested the burners on the stove and they seem to be working fine. the flames are blue with an occaional yellow flair. i also tried at home where i have a 30v plug. It looks as if the former owner replaced the propane regulator once or maybe moved it. Any ideas on how to fix it. could it be something with the winterizing? since it is a hydro flame...

[FLY_4_FUN]

I also thought that an onboard 12v batt was required for proper operation of 12v systems. Perhaps put a battery on (I assume you have one somewhere) and see if it fixes your problem. Just because some things work on 12v with the converter only....does not mean that the converter can supply enough power to run several things (fridge/furnace/lights etc).

[ksg5000]

As Artum Snowbird has indicated a stuck sail switch maybe the culprit. The manuals for most furnaces are on-line and if your handy with Google you should be able to find. Another alternative is to call a mobile RV tech - s/b easy fix for them.

[ScottG]

midnightsadie wrote:
you do need a good 12volt battery even when plugged into shore power.

Not on a 2015 RV. The converter is clean enough that it doesn't need the filtering of a battery.

[westend]

StarcraftNick wrote:
i currently don't have an auxiliary battery for the camper. Are you saying this is needed? could you explain why, so i am better in the know. Because it was working without one for a bit. thank you!!

The battery serves as a separate power source and also acts as a capacitor for the onboard 12V converter. It's mandatory to have a charged battery in your trailer if it's moving because that is the power for the Emergency Braking system.

You will need to confirm if you have continuous 12V power available at the furnace, on the circuit board and through the various switches/safety devices. A service manual and troubleshooting chart is available from Bryant RV.

Bryant RV service manuals

[StarcraftNick]

i currently don't have an auxiliary battery for the camper. Are you saying this is needed? could you explain why, so i am better in the know. Because it was working without one for a bit. thank you!!