Payne gas furnace cycles but shuts down without ignition

[Lacey29]

My furnace has been on the fritz for a few years and will fail to ignite.   It goes through all the cycles including the blowers and firery red glow but will eventually shut down.  I called a furnace repairman that said more than likely it was the circuit board and it would be pricey to replace....but eventually it will fail for good.   I can get it going if I turn off the power at breaker box and turn it back on...sometimes that doesn't work and I litterally give it a kick (not hard) and then turn that breaker on and it will fire up.  The guy I spoke to said it was probably a magnetic field that isn't letting go and shutting off the power and sometimes jaring it breaks the field and allows it to start up agian.  This furnace is only about 7 years old.  Any other ideas of what might be going on? 

[RegUS_PatOff]

[user=38703]Lacey29[/user] wrote:

... The guy I spoke to said it was probably a magnetic field that isn't letting go and shutting off the power and sometimes jaring it breaks the field and allows it to start up agian.... 

? ? 

When it fails to run  ... does the Flame come ON for any length of time ?

 

[Lacey29]

No, when it's acting up and is only cycling it does not fire up at all.  Once I get it running it will go until the house is at the selected temperature and shut off.  After that it will usually go anywhere from a couple more normal cyclyes to a day of normal operation....usually depending on how cold it is outside.  The colder it gets outside the more often I have to go out and kick it in the pants to get it heating again.  Sometimes I can hear something running in it like a fan sound, but it's not the full blown blower running. 

[jb8103]

What you hear running is probably the Induced Draft Fan motor. The fiery glow is likely a hot-surface igniter. So you're getting that far, but apparently the furnace has nothing to ignite - gas, that is - and will stop trying after a set time.

If you have the book, check the Sequence of Operation page. The manual and/or the Sequence of Operation card might be stored in a pocket inside the furnace.

If you open the furnace doors, you will likely find a wiring diagram pasted onto the lower door, along with other information, possibly a fault code legend.

I don't know about this Payne, but mine has LEDs on the board that will blink a fault code. I have to open an access panel to see them, if I remember right.

In my opinion you don't want to kick this unit too often. They are expensive.

(Looking like a run on stuck gas valves, Reg.)

[Lacey29]

What you hear running is probably the Induced Draft Fan motor. The fiery glow is likely a hot-surface igniter. So you're getting that far, but apparently the furnace has nothing to ignite - gas, that is - and will stop trying after a set time.

Yes, you're exactly right.  It's trying to fire up but the gas is for some reason is getting locked out. 

I'm not giving up on getting to the bottom of this but have been uber busy and this has been (oh god am I really going to say this!) put on the back burner! (Sorry folks!) 

I need to find the manual that came with the furnace and then go up into the attic and spend some quality time with my furnace and jot down all the flashing codes it throws at me.  Oh, did I mention this is a horizontal unit in the space above my garage?  Not the happiest place to access.  Once I get the info I'll post back and go from there. 

I don't really kick the furnace just give it a couple thumps with my hand and it unsticks whatever is the matter.  Okay....I should do that either!

 

[applianceman18007260692]

Get a dry brillo pad and clean the flame sensor

[Lacey29]

Can you tell me where I would find the flame sensor and what it looks like?

[jb8103]

Here is the Good Book:

http://www.gogeisel.com/geiselonline/support/Payne_Owner_Manuals.html

See the illustration for your horizontal version, item 14.

But this humble grasshopper asks, why suspect the flame sensor under these circumstances? It's not lighting up in the first place.

Of course a cleaning is always good. Check your filter too.

Be careful if you go in there. Read the manual first. There's 120 VAC present; and if you smell the slightest whiff of gas, call a tech right away.

[applianceman18007260692]

lacey the flame sensor is mounted in front of the flame fartherest away from the gas valve.

[Lacey29]

Thanks for all the help folks!

 Today I crawed up and snuggled with my furnace.  It was in it's non functioning mode (perfectly quiet) and the led code was flashing 21 (Two short and one long flash).  Given that code the manual reads: Gas heating lockout-Control will NOT auto reset.   Check for mis-wired gas valve.  /  Defective Control (Valve Relay).

I put the covers back on which restored power to the unit and with in a minute it fired back up, which I expected it to.  It ran until it reached 71 whick was where the thremostat was set.   I bumped the thermostat up one degree and the furnace kicked back on until it reached 72.  Though, it's only a matter of time before it stops and goes back to non-function. 

I looked around for the flame sensor and still didn't see it.  I know it's behind metal and can't see it head on, but how hard can it be?   It should be just below the surface ignitor.  Back up there to look again.  A couple years ago I broke the surface ignitor when I was looking around for something obvious for the malfunction...I know to be much more carefull this time.  

[RegUS_PatOff]

from the previous link:

 

It kinda shows where the Flame Sensor is ... (and it's wires)

PG8D Operation & Maintenance Manual

[Lacey29]

I found the flame sensor, took it out, cleaned it with fine steel wool (looked fine even before I cleaned it), put it back and waited to see if the furnace would stay in functioning mode for more than a few cycles.  No luck...still shutting itself off after only a coulple hours with the LED flashing 21.  The filter is clean,  but no change whether it's clean or dirty.  Plus, when this first started I figured it was the thermostat so I went out and bought a new programable one and that didn't make a difference either. 

Any other ideas I can try out? 

[RegUS_PatOff]

from maybe a similar Controller:

[align=left]"Status Code 21[/align]

[align=left]GAS HEATING LOCKOUT - This status code indicates the main gas valve relay MGVR on the variable speed furnace control is stuck closed or there is a miswire/short to gas valve wiring...[/align]

[align=left]The variable speed furnace control will NOT auto-reset.[/align]

[align=left]If the problem persists on an intermittent basis, replace the variable speed furnace control."[/align]

[align=left]http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/58mvp-10sm.pdf[/align]

[align=left]or maybe just replace the on-board Gas Valve Relay ?[/align]

[jb8103]

The symptoms you first described indicated a sticky gas valve and the fault code seems to confirm that.

Turning off power at the breaker would reset the lock-out switch, restoring the circuit to the gas valve relay. Likely, the gas valve is a combination redundant gas valve, with a regulator and two valves. There are several moving parts in these things, like a couple of solenoids, a servo, a diaphragm or two. Any of them could stick. After you reset power from the circuit breaker, thumping the unit once or twice would jar the sticky component loose, for one or two cycles, anyway. So it's unlikely to be a miswire or an electrical problem, but rather a sticky widget. Well, it could be a loose connection, too.

In either case you need a tech to come over and check out the gas valve.

[Lacey29]

Thanks for all the help everyone. 

JB8103, I'll take your advice on having a tech come out.  But am curious, if what you describe is the culprit (and it sounds very likely) is this the replacement of one part?  If so what part(s) would that be?  I'd like to have an idea of costs before I commit myself, since the furnace is still working and money isn't exactly growing on trees right now.

Thanks

[jb8103]

The tech just might find the problem is a poor connection at a DIP switch. That would be the best lemon for your lemonade.

A good tech will charge X amount for the service call, diagnose the problem, and give you a repair estimate. Then you can decide. But you will have to pay for the service call.

[applianceman18007260692]

It could be a loose or corroded ground wire from burner to brain especially if you have to kick it. LOL. tap on the gas valve also. Could be the operator coil going bad. Might need a new gas valve.

[Shootist]

Does your furnace have a Honeywell "smart Valve" system? You can tell by the valve having two "molex" plugs on it. I can't tell you how many bad "smart Valves" I've seen cause the problems you describe.

The only other thing I can suggest is make sure the furnace is grounded properly and make sure your pigtail has that center ground prong in place.