Atwood RV Furnace will not start after changing propane cyl

[64aggie]

I recently changed over to the reserve cylinder when I had the other 30 lb. propane cylinder refilled. Now my furnace, Atwood Hydro Flame 8531-IV-DCLP, will not start. When I turn it on, using the thermostat, nothing happens. The blower does not run as it normally did prior to the furnace lighting. I have tried switching cylinders. My Atwood Hot Water heater is working & I can use the Atwood propane range.

I have 12.4 volts through the off/on switch & the circuit breaker. The fan will run if I jumper this to the motor. There is also 12 volts from the thermostat and the ground wires all check out.

All web troubleshooting articles refer to a "relay" with four terminals. My unit does not have this, only the circuit board. Where is this relay? Also I get no light or flashes of the circuit board LED.

Any and all help is greatly appreciated. Thanks!

[PJ4284]

This maybe a really dumb question. Do I have to have the battery hooked up or a good battery for the furnace to run even when the camper is plugged in?

[PJ4284]

dougrainer wrote:
The BLUE wires just send a 12 volt signal to the furnace to ACTIVATE the furnace to heat. Once the Blue wire sends the 12 volt signal the Fan relay is energized and the motor should come ON. NOTHING will happen until the Fam motor runs. So, you need to jump the 2 blue wires AT the furnace, not at the Tstat. Also, ONE of those blue wires must have 12 volts positive. So, IF you have no 12 volts at either BLUE wires that is the start of your problem. The blue wires start at your furnace and the Furnace supplies one of those Blue wires with the required 12 volts. It makes no difference which blue wire has the 12 volt power, just one of them. Doug

Hey Doug, Thanks. I did connect the 2 blue wires at the motor. I put in parentheses Tstat because I was told the 2 blue wires at the motor called it system to heat and the motor would kick on. Anyways, After connecting the 2 blue wires nothing happened. One blue does have 12 volts. When I take the red wire to fan motor and connect it to the same terminal (as the blue that has 12 volts) on the relay the fan will kick on but I do not hear any clicking like it wants to ignite. When I put the red back on the relay where it is suppose to go and reset everything nothing happens. Of course I do not have the propane on at this point.

[wa8yxm]

Regarding that 6300.. I'd consider upgrading the "Electronics" part to a Progressive Dynamics 4600.. it's a Bolt in replacement for that part.

From time to time we speak of some very bad converters that can among other things damage your battery..... Not sure if the Parallex 6300 is. but Parallex bought out Magnatek and their 6300 was. and you did a fairly good job of describing the Magnatek 6300 (Unfiltered and battery circuits)

This likely has nothign to do with the furnace. but it will improve battery life.

[dougrainer]

The BLUE wires just send a 12 volt signal to the furnace to ACTIVATE the furnace to heat. Once the Blue wire sends the 12 volt signal the Fan relay is energized and the motor should come ON. NOTHING will happen until the Fam motor runs. So, you need to jump the 2 blue wires AT the furnace, not at the Tstat. Also, ONE of those blue wires must have 12 volts positive. So, IF you have no 12 volts at either BLUE wires that is the start of your problem. The blue wires start at your furnace and the Furnace supplies one of those Blue wires with the required 12 volts. It makes no difference which blue wire has the 12 volt power, just one of them. Doug

[PJ4284]

Ok I am curious. I have the same issue with an Atwood 8520-IV. I bought a new Thermostat, time relay and had the board tested. Fuses are good, Breaker is good. All are functional. When I turn the thermostat on the blower motor will not turn on. When I connect the 2 blue wires at motor(Thermostat) the motor will not turn on. When I connect the red (motor) and Black(motor) or bypass them to a battery the motor turns on and blows strongly. Now, I have power to the manual on/off switch. Power to the relay through blue wire but nothing past that. I am curious as to what wires do I check or what wire was crimped badly on the other guys? Any help would be greatly appreciated. BTW, I was told by the service dept at a dealer if I connect the 2 blue ( thermostat ) at motor the fan-blower should kick on if it doesn't its a wire issue. Where do I start?

[Sodakdave]

Thanks SoundGuy. I had noticed the thread was old but figured it was worth throwing out there. The good news is that I was able to resolve the issue (bad crimp on a connector). Thanks anyway.

[SoundGuy]

Sodakdave wrote:
Was this ever resolved? I have the exact same issue.

This thread is over 5 yrs old and the OP no longer has any posts showing as active. Probably hasn't been around for a l-o-n-g time so I wouldn't hold your breath waiting for a response.

[Sodakdave]

Was this ever resolved? I have the exact same issue. I was on a spare LP tank then switched back over to my main tank. Now the furnace will not light (fan does not clear the chamber, nothing happens). I am able to jumper to run the fan so we know the motor is working and power is making it to the furnace. I tried jumping the two blue (thermostat) wires and even after waiting for the delay, nothing happens. I gave up and assumed the board had gone bad so i ordered a new board and still nothing happens.

[John_Joey]

Golden_HVAC wrote:
My guess is that the furnace stopped working, and then you tried changing the cylinders, and then found it is still not working...

That was my first thought also. Changing propane cyl and then no fan simply do not go together.

Now if I assume it didn't work prior to the change, and the furnace was being look at by someone, then I might also assume that the rocker switch for the fan may have been thrown, and left in the off position.

[dgcarlson]

Atwood HydroFlame 7900, blower starts, but intermittently the ignition will not "click". I was able to start the burner by slapping the inside of the air duct, so I'm thinking it's a sticky airflow switch. AGain, once the ignition clicks a few times, the gas will always ignite and heat starts. The blower needs to be up to a certain RPM at the start to close the airflow switch, before the gas valve opens and ignition starts. Comments?

[64aggie]

First let me thank everyone for their response and input. It is great to always know you can get such help and assistance from RV friends.

No, I have not gotten to the bottom of our furnace problem YET! However I am convinced we will resolve the issue with your continued assistance.

I have taken most of our RVision's 8226 Trail-Lite apart and have found nothing significant, but a few interesting issues. Everything works normally except the furnace, Atwood 8531-IV-DCLP, and the Propane LP Detector, Atwood Protechtor series 2001.

(We have a 30 amp Internal Surge Guard)

I thought the LP Detector, which had malfunctioned for several days, had failed and had purchased a replacement, Atwood model 36719 LP_DOW. I installed the new detector and it did not work, 12.4 vdc and correct polarity. I thought it was DOA, called Atwood and they said to return it. The concurrent problems with the furnace, the detector coupled with your inputs made me curious about the low DC voltage. I hooked the old detector to our Wagan Power Dome EX and it functioned properly. The DOA new detector also functioned as designed when tested in the same manner.

(According to Atwood "this alarm has a seven year life." It also has an end of life mode and states it must be replaced after it has been powered for 7 years +/- 128 days. Had any of you heard of this? Does it apply to the series 2001?)

I then pulled my 12 volt battery and it tested at 13.85 volts, but I was only getting 12.45 volts to the Detector. Next I started checking out the DC portion of the Power Supply/Converter.

It is a Parallax 45 amp, series 6300, model 6345. It has nine(9) DC lugs fused at 15 amps each. The first six (6) are unfiltered and the remaining three (3) are filtered for accessories such as the stereo and such. The furnace and LP Detector are connected to unfiltered lug #5 which is at 12.25 volts with shore power connected. (All six of the unfiltered measure the 12 25 volts with shore power and 12.45 volts without. The three (3) filtered lugs measure 13.81 with shore power and 13.0 without. The LP Detector works properly when connected to one of the unfiltered lugs. Tomorrow I will connect the furnace and LP Detector to this lug and see what results.

Is this voltage drop between these lugs normal? What would cause this drop? Have any of you upgraded your power supply/converter? What do you recommend? The 45 amp has been discontented. Can you upgrade using the 55 amp?

Our thermostat is a Duo-Therm analog by Dometic number 3107612.008 0212. It controls our furnace as well as the air conditioner and the fan, auto & speed. It appears to operate on 7.5 vdc? Do you have any experience with this unit. How do you check it out or troubleshoot? Is there a remote relay associated wit it? I have not found any relay associated with the furnace, only the ignition control board?

Again, thanks for your help and advice!!!

Best wishes to all for 2013

[wa8yxm]

When I read the subject line I was thinking "Excess Flow Valve" on the propane too but...

THE BLOWER WILL NOT RUN

The first step in the ignition sequence, even before the solenoid valve opens turning the gas on, is the blower First it runs, comes up to speed, sails the sail switch THEN gas is called for.

So, we have one less thing to check, We know it is not a propane issue since propane is never called for.

From the op's descripton it can be only one of two things.

1: The thermostat (This includes the wires that hook it up)

2: The furnace controal board

IF, and I stress IF it turns out to be the control board.

Dinosaur boards make first rate replacements, better in my not very humble opinion than the original, and less than half the cost.

[dougrainer]

snowdance wrote:
X-2 what eHoefler said. Turn propane off and on again very slow.

His Water Heater and Stove/Range work. So this would NOT be the problem. Doug

[snowdance]

X-2 what eHoefler said. Turn propane off and on again very slow.