Amana GULA090AX50 Furnace - Furnace starts then stops

[AccApp]

The flame sensor is just a metal rod, a very small amount of corrosion wiil prevent the tiny amount of current passing from it to ground.

[_Carl_]

I used sand paper this time (steel wool was not getting it shiny like you said) started with 320 grit - 400 grit -1500 grit (left it smooth so very little groves for carbon to sit in) Then I wiped it down with a clean paper towel until it would leave no black residue.

I don't know if the pics do it justice but it looks like a piece of polished stainless steel. Time to install it and see how it goes. Ill post back once I've verified its either working or not. Thanks 

cleaned flame sensor pic 1

https://i.imgur.com/86NdDMK.jpg

cleaned flame sensor pic 2

https://i.imgur.com/Uj1tCt0.jpg

[john63]

I'm with AccApp...flame sensor.

Had to clean mine every 2 years.

Symptom would be...

Flame ignites for 2 or 3 seconds...then shuts down.

Keeps attempting to re-ignite...indefinitely.

[_Carl_]

AccApp, Big thanks to you ...It's fixed. Since I cleaned it so good it shines like new metal it has not failed once after all night and all day. That was the key..000 steel wool wasn't getting it, ultimately the answer for me was sand paper  320 grit - 400 grit then 1500 grit and a lot of elbow grease.

Considering I cannot afford to pay a furnace man their high priced service call charges you really saved my bacon and it is very much appreciated. Also a big Thank You to the creator of this forum as its obvious you do this to help out people like myself. There may be a lot negative things happening to people with their appliances and in life at times but you guys are certainly taking the edge off for many people...much appreciated 

[_Carl_]

I cannot believe it but the issue is back.

Here is a rundown on sequence of events:

1. About a year ago the furnace was coming on and just letting the blower run continuously with no flame. A repair man came and tapped on the pressure switches and the furnace started working normally until recently. He said they can get stuck sometimes and they may work for 2 days or two years but eventually would have to be replaced ( he did no testing with equipment)

2.   A few weeks ago It started with new issue - burners not staying on during startup but always would on the 2nd try then furnace would work normally..then it took more attempts and sometimes would work..then it would cycle about 5-6 times until lockout. I tested the primary auto limit switch for continuity ( out of furnace - cold) result = no continuity.  I ordered a new one and tested it (out of furnace - cold) result = had continuity... with new limit switch installed it worked normally for about a week. ( I has also periodically tapped the pressure switches like the repair man did at the beginning as I was testing components) 

3. At this point I came to this forum and ended up thoroughly cleaning the flame sensor until its shined like new metal which made it work normally for a few days.

 

Worth mentioning:

1. During the fall before the furnace was in use we had a few power outages, one of which the power cycled on and off quickly several times.

I mention this because during my testing of both pressure switches one gave very normal readings ( to me at least) the other much different readings as can be seen below. 

Method Of Testing:

Multimeter positive lead connected to one of the two terminals on pressure switch  (with furnace wires still connected) , negative lead to a solid ground.

Right Pressure Switch:

maintains 26.5 - 26.9 v during initial starting sequence (never fluctuated beyond this)

when burners light up it drops to 24v and stays there...seems normal.

 

Left Pressure Switch:

fluctuating voltage during initial start sequence  0.15 v - 00.0v - 24.6v (burners try to light)- 7.6v - 0.00v - 24.6v (burners try to light) - 00.0v - 24.6v(burners try to light) -00.0v

That being said I did this test for the pressure switches http://www.hvachowto.com/2015/10/26/test-gas-furnace-pressure-switch/ and they both passed the test.

 

I'm concerned now maybe all this randomness is the result of a faulty control board due to the power going on and off and having damaged it ?

Also during the summer my propane tanks main valve was replaced..so I concerned about a possible low gas pressure issue if they didn't adjust that properly ?

 

[AccApp]

it sounds like that left pressure switch is the issue.

[_Carl_]

Ordered two, will be here Jan 8th. I'll update when I get them installed. Thanks 

[AccApp]

Jan 8th? What part of Bumf*** do you live in? Is there not a local supply house that would have them in stock?

[AccApp]

Then again, I'm homebound due to a Blizzard anyways.

[AccApp]

Have you made any progress? Did your pressure switches ever get delivered?

[_Carl_]

So the issue went away for a while then came back . I've noticed it seems to only do it when its really cold like 5 degrees Fahrenheit or lower. since it warmed up it hasn't done it since....just when its really cold.

[AccApp]

you're not on LP (propane), are you?

[_Carl_]

yes I'm on propane. I've been wondering about my pressure, I called my propane company but never heard back.

[AccApp]

Well, there you go! Lp at around 5° f starts to not want to vaporize to get into the pipe. I think at about -10° it's done. One of the awesome catch 22's about lp as a central heat source.

[_Carl_]

its was near -15 when it was at its worst when I first posted my issue here. what is the solution ? I talked to others on propane where I live and none of them had the issue I had.

[AccApp]

Maybe wrapping some of that pipe heater wire around the tank to keep it above 10°. 

[AccApp]

3 minutes ago, AccApp said:

Maybe wrapping some of that pipe heater wire around the tank to keep it above 10°. 

Which is apparently a very bad idea:

https://www.bournesenergy.com/news/propane-in-cold-weather-800937483

[_Carl_]

why did none of my neighbors have this issue and they all have propane furnaces as well ?

[AccApp]

6 minutes ago, _Carl_ said:

why did none of my neighbors have this issue and they all have propane furnaces as well ?

Maybe theirs are fuller or have partial ground contact. Could be any number of factors and you are just the canary in the coal mine.

[_Carl_]

I had 50% when it started, one neighbor said he had 20% in his tank during the -15 degree temps and had no issues.

my line is buried..only part of line exposed is going from the tank ( line everyone else) to the ground.

this does not make any sense.

[_Carl_]

Apparently -44 degrees Fahrenheit is the magic temp where propane has issues. but i did find this info " The lower the temperature of the tank, the lower the gas pressure (PSI); it doesn't need to get down to -44 for the pressure to be inadequate to run your appliance. As mentioned, you could make a little shelter with a light bulb inside to keep the tank cozy, or buy a dedicated tank heater blanket (which not one single person has where I live..North Central Missouri) this answer was from a guy using a 20 pound tank also. 

But it does make me think if my pressure is already set to the bare minimum then the -temps hit it could very well be the issue..tough when you cannot get your propane company to even call you back since they never answer the damn phone. Is upg known to be hard to deal with ?