Ok furnace would start then in seconds go out blower still running the it would reignite the after a few seconds burner goes out again then finally it stays lit. I had the sail switch replaced didn’t help then replaced circuit board and now doesn’t cut out at startup but now runs for about 5 minutes the flame goes out and blower still blows as it should but while blower is still going it reignites and runs again for about 5 minutes then goes out again. Could it be a bad Thermostat??????

Furnace fan comes on...purges...main flame lights run five minutes then flame goes out and fan continues to run...then flame lights repeatsBlocked/obstructed discharge and/or return....lack of proper airflow thru heat exchanger causes 'high limit switch' to open (shuts down gas valve).Fan cools heat exchanger high limit switch closes and circuit board opens gas valve ....called 'limiting'Check vents/registers, return air and anything up against furnace that would block return air

Mine does that if parked for a while, and gets damp,at the igniter, just starting a few times clears it

No obstruction intake or out put RV tech has gone through it, cleaned it check for obstruction. Spent $ 300 in repairs and parts and still not working right.

Did they measure how hot discharge was getting right at furnace and how fast it got hot?High temp limit switch Trips when temp gets to hot in heat exchanger Obstructions/blockages could be within the ducts, at registers and the path of return airflow...not just at furnace combustion intake/exhaust Might check LP System Pressure....too high and furnace overfiresS/B 11" WC (0.4 psi) measured with manometer and at least 50% of propane in service

I’ll check for obstructions and then talk to service tech tomorrow

Furnace problem | Good Sam Community

okiejoe
Explorer
Dec 22, 2018
Hey guys let’s not go to raggin on my RV Tech he is good at what he does, I guess I haven’t relayed all the facts but the parts he’s replaced were bad ie ciurcut board had corrosion on it from moisture and sail switch was bad both tested bad but apparently there is another problem not detected yet, and it’s intermittent and we all know how intermittent problems can be hard to diagnose. Trust me he’s not throwing parts at it and I wouldn’t let him but sometimes things can be a real pain to get working right.
BFL13
Explorer II
Dec 21, 2018
Phil, the whole RV is like that. Remember the Zoomies' saying that they ride up there in what are just a bunch of lowest- bidder parts flying in loose formation.

As you have stated before, redundancy is everything!
pnichols
Explorer II
Dec 21, 2018
gkainz wrote:
pnichols wrote:
Sometimes there can be a valid case for "throwing more parts at it":

I recently told my outstanding RV repair shop to replace several parts in our rig's refusing-to-light 13 year old furnace, in order to both - fix the current problem, plus while they were in there go ahead and replace several common furnace components likely to be near needing replacement so that - we don't get surprised by a failing furnace while out and about on an RV trip. It's called "Preventive Maintenance".

My repair shop refused to do that - they insisted on fixing only the exact problem by trouble-shooting to find and replace only the exact part needed. (See above in this thread for what the freak cause of my furnace problem was.)

I now have a functioning furnace while paying for only one failed furnace part. However, I now also have an RV furnace still with a bunch of 13 year old parts inside it that could surpise us anytime by having to tolerate one or more freezing drycamp nights before either - running the Onan all night to power an electric heater, having to move to a $$ full hookup and boring commercial campground, or having to truncate the trip and hurry home.

I guess I'm slow to learn that ... repair shops love to replace one failed part at a time so as to make shop labor charges over and over by replacing only one failed (hopefully different part) at a time over time.

I guess the difference is asking for a furnace repair vs a furnace rebuild? Do they offer such a thing?

A good point and a good question! I didn't think to ask specifically, but they probably could have suggested it and I probably would have agreed.

We HATE failures in the field when RV'ing because we could be out in a field when something fails.
gkainz
Explorer
Dec 21, 2018
pnichols wrote:
Sometimes there can be a valid case for "throwing more parts at it":

I recently told my outstanding RV repair shop to replace several parts in our rig's refusing-to-light 13 year old furnace, in order to both - fix the current problem, plus while they were in there go ahead and replace several common furnace components likely to be near needing replacement so that - we don't get surprised by a failing furnace while out and about on an RV trip. It's called "Preventive Maintenance".

My repair shop refused to do that - they insisted on fixing only the exact problem by trouble-shooting to find and replace only the exact part needed. (See above in this thread for what the freak cause of my furnace problem was.)

I now have a functioning furnace while paying for only one failed furnace part. However, I now also have an RV furnace still with a bunch of 13 year old parts inside it that could surpise us anytime by having to tolerate one or more freezing drycamp nights before either - running the Onan all night to power an electric heater, having to move to a $$ full hookup and boring commercial campground, or having to truncate the trip and hurry home.

I guess I'm slow to learn that ... repair shops love to replace one failed part at a time so as to make shop labor charges over and over by replacing only one failed (hopefully different part) at a time over time.

I guess the difference is asking for a furnace repair vs a furnace rebuild? Do they offer such a thing?
pnichols
Explorer II
Dec 21, 2018
Sometimes there can be a valid case for "throwing more parts at it":

I recently told my outstanding RV repair shop to replace several parts in our rig's refusing-to-light 13 year old furnace, in order to both - fix the current problem, plus while they were in there go ahead and replace several common furnace components likely to be near needing replacement so that - we don't get surprised by a failing furnace while out and about on an RV trip. It's called "Preventive Maintenance".

My repair shop refused to do that - they insisted on fixing only the exact problem by trouble-shooting to find and replace only the exact part needed. (See above in this thread for what the freak cause of my furnace problem was.)

I now have a functioning furnace while paying for only one failed furnace part. However, I now also have an RV furnace still with a bunch of 13 year old parts inside it that could surpise us anytime by having to tolerate one or more freezing drycamp nights before either - running the Onan all night to power an electric heater, having to move to a $$ full hookup and boring commercial campground, or having to truncate the trip and hurry home.

I guess I'm slow to learn that ... repair shops love to replace one failed part at a time so as to make shop labor charges over and over by replacing only one failed (hopefully different part) at a time over time.
Old-Biscuit
Explorer III
Dec 21, 2018
Have him throw some more parts at it....bound to find a cure eventually
okiejoe
Explorer
Dec 21, 2018
Hey Ole Biscuit
It’s working just takes any where from I
1 to 3 try to ignite but always invites by the 3 try, never go to lock down. What’s odd is it only does that on the first ingnition from being off for a day then fires the first try. That’s what’s odd, that’s why he going to just check it throughly, the other problem was duct restrictions which after it started and was heating would shut down after 6 minutes then would refire before blower shut off because it hadn’t reach thermostat setting yet. Limit switch would shut it down due to restrictions in duct causing over heating, that is solved now.
Old-Biscuit
Explorer III
Dec 21, 2018
okiejoe wrote:
Well the original problem was shutdown at ingnition, I took and still doe shutdown 1 to 3 times before complete ingnition and each part improved it but after ingnition it would only run about 6 minutes then flame out due to duct restrictions from too many. Tight bends but now that’s solved. I got to take it back to him to check the ignitor and and just give really good check of the electrical system of the heater. So in a nut shell there are a combination of things that were going on but it’s narrowed down to just the failing ingnition. I’ve been using him for sometime and he always does me good.

"No obstruction intake or out put RV tech has gone through it, cleaned it check for obstruction. Spent $ 300 in repairs and parts and still not working right."
okiejoe
Explorer
Dec 20, 2018
Well the original problem was shutdown at ingnition, I took and still doe shutdown 1 to 3 times before complete ingnition and each part improved it but after ingnition it would only run about 6 minutes then flame out due to duct restrictions from too many. Tight bends but now that’s solved. I got to take it back to him to check the ignitor and and just give really good check of the electrical system of the heater. So in a nut shell there are a combination of things that were going on but it’s narrowed down to just the failing ingnition. I’ve been using him for sometime and he always does me good.
Old-Biscuit
Explorer III
Dec 20, 2018
RV Tech should refund your monies cause he was nothing more then a 'parts replacer'.

Simple diagnostic test would have pointed to limit switch.

Symptoms pointed me to it and I'm on the other end of the 'World Wide Web' :S

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