RV Heat Furnace Cycles on three times and shuts off..

[sscheitel]

My heat in my 2018 Jayco JF 32BHDS with Atwood furnace turns on:
- blower come on
- cycles to fire up
- warm air comes out of the registers
- air turns cooler and fire goes out but blower continues
- it fires up a second time....air gets warmer....same results....air blows cooler but fan stays on
- it fires up a third time....same thing occurs
- after third attempt the system shuts off

It sounds like it starts up...fires up and then something is causing the fire in the furnace to extinguish

I have have all registers open.

What gives?

[sscheitel]

Scheduled to go to Jayco dealer next week. I will advise on the resolution.

[Old-Biscuit]

sscheitel wrote:

SidecarFlip wrote:
screw with it and you'll eat it. Let the dealer handle it. Simple answer. WARRANTY

sound advice. though I might have my dealer replace it with a dino board.

WHY:H

Replace a perfectly functioning circuit board due to a issue with spark electrode :S


Why wait for dealer......change it yourself. Dealer/warranty is not going to use a Dino Board regardless

[sscheitel]

SidecarFlip wrote:
screw with it and you'll eat it. Let the dealer handle it. Simple answer. WARRANTY

sound advice. though I might have my dealer replace it with a dino board.

[SidecarFlip]

screw with it and you'll eat it. Let the dealer handle it. Simple answer. WARRANTY

[sscheitel]

hey wa8yxm would you say that the Dino board is of better quality then the Atwood OEM?

It sounds like you are...in that case I would want to go that route...

ohh another tidbit....I was camping last week and during a heat index of 116 in VA and my AC on for hours....my furnace started making a thumping/churning/rev'ing sound....had to pull the fuse and waited a few hours and noise went away....but something definitely did happen....ohh and the AC was on for all of that so this seems very plausible.

I think the analog thermostat had a malfunction. Have since replaced with digital thermostat.

[wa8yxm]

I know that feeling.. (Read that happned to mne) Somne good advise above but here is what I found.

Symnptoms. Exactly the same as yours

Inspetion. Flame lit, then shut off (Blower continued through the cool down, then went into PUrge then it relit.. Total 3 tries)

THen it went into Ignition lockout.

After MUCH testing (As it happens I knwo how to do this stuff. I don't recommend less you know how) Including testing the thermocouple (THey almost never fail)

I determined the control board was not sensing the flame.. .

Mine is a "Single Wire Ignightion" This means the same wire that carries about 1,000 volts A/C to make it spark also carries about 0.480VOlt DC back from the flame sensor (Thermocouple)

Well my THEORY is that when the board switched from "Make sparkes" to "Sense flame" the timing was off a bit and the flame sensor chip got hit with 1,000 volts or more.. ZAP a zowie it was toast

I priced a new board (over 200 dollars) And then priced a New Dinosaur Boards board (Fan 50 for my RV) at less than half the cost of an Atwood OEM.

Opened the box..... Very impressed by the quality of the Dino board on first look.. At second look... Found a neat little gas discharge tube right where you'd put one to protect the flame sensor chip against just the kind of failure I figure happend.

I got my Dinosaur board from American RV in California. NOTE: Many companies with that name. You want the California one

(One in MI changes my oil, ONe in GA replaced an A/C for me.. All different).


NOTE: I recommend trying the NO COST solutions suggested above befor throwing money at it

[Old-Biscuit]

Flame has to PROVE it lit or circuit board shuts down DC to gas valve.....don;t want raw fuel flowing (BOOM)

Spark electrode is used as return path for flame lit signal (miliamp signal generated by the flame--rectification---ions etc)
Anyway.this miliamp signal goes back to circuit board proving main flame is lit so circuit board holds DC on gas valve until thermostat reaches set temp point...then DC is stopped by t-stat

Mis-aligned electrode, dirty electrode (soot/carbon), dirty/loose high tension for spark electrode, cracked ceramic insulator, poor ground
Above are 'common' issues...could be more involved (gas leaks, obstructed exhaust, circuit board issues, low LP pressure ----furnace is biggest hog of all appliances)


Under warranty......let them pull it apart and fix

[SidecarFlip]

3 times is the key. The furnace is circuitry is attempting to 'prove' there is ignition and a flame and cannot so it shuts down after 3 attempts. Let the dealer fool with it. Should not cost you anything but time.

[sscheitel]

its under warranty. will take it in. thanks

[SidecarFlip]

It's the sail switch. Take it in and have it fixed under warranty.

[time2roll]

Sounds like the furnace is thinking the burner has failed to light.
Typically it will try three times then quit.
I assume you are plugged in with 12+ volts on the battery.

I would take it back under warranty. Don't monkey too much or it will be your fault.

[sscheitel]

newman fulltimer wrote:
your bottles were not properly purged so has alot of air in them furnace is high propane demand.

so get your bottles repurged bet the oroblem goes away

Even though it worked 2 months ago when we first took delivery of the rv?

BUT I have disconnect the main two tanks a few times to install my hitch.

I will also add that all other gas fed appliances work as well. (oven, outdoor stove, indoor stove & hot water heater/LP)

[newman_fulltime]

your bottles were not properly purged so has alot of air in them furnace is high propane demand.

so get your bottles repurged bet the oroblem goes away