York gy8s080b16dh11b problems :(

[delawaredrew]

Hi all,

I have a York GY8SB1611DH11B furnace that is giving me problems. I work on gas appliances all the time so it seemed that I could take a stab at it.

It has been failing to ignite for several days, The ventor would run then the blower but no ignition.  I finally got under the house to check it out today. It was flashing the code for a pressure switch problem and indeed the port off the ventor was clogged with grit.  So I cleaned that out and it tried to start, even going so far as opening the valve. 

The ignitor was not connected at that point so it didn't ignite but seemed like it would have.  It went into lockout due to lack of ignition.  Being impatient I turned off the power to it for a few minutes thinking it might reset the board.  After powering it back up it blew the 3amp fuse on the board when it tried to start.

I replaced that fuse and the indicator light lit up green so I figured all was ok.  However when I turned the thermostat up it blew it again.  I replaced the fuse again, and disconnected the ignitor just to be certain it wasn't shorting it out and tried again.  It blew the fuse again.

What do you think?  I'm thinking that board has a issue like a bad relay, but it seems like a heck of a coincidence that it would fail just from being power cycled?  What exactly does the fuse protect on this? 

Thanks

Drew

[RegUS_PatOff]

this may be your manual, but I don't see a Fuse on the Board ..

I'll do some more searching...

upflow

http://yorkupg.com/PDFFiles/268893-UUM-A-0407.pdf

downflow

http://www.yorkupg.com/PDFFiles/98601-UUM-A-1104.pdf

[delawaredrew]

If not exactly the same it is similar, I couldn't find a manual for it either.  The fuse is listed as #14 on the parts list, and it is vaguely shown on the board diagram but not numbered or marked at all.  It's the vertical bar on the lower left of figure #9.  It is on the control board itself.

I've been thinking about it all day but nothing new has come to me.  If I understand the sequence of ignition, the fuse blows when the board tries to turn on the ventor/combustion air fan.  I tried it with that fan disconnected and it still blew the fuse.  I've now used up all the 3a fuses the local autoshop has in stock!  I can get a new board but will be ticked if I dump $100 for a unreturnable part and it doesn't do it. 

I may have make or get a resettable jumper fuse that I can test with. I used to have a 15a one that I used for MW ovens that came in handy.

This pic I stole off ebay is a similar board, the fuse is the purple thing in lower left.

[RegUS_PatOff]

somewhere I remember reading the the 3A Fuse protects the 24v Transformer Secondary.

After looking again at the wiring diagram, the Transformer Secondary powers the House Wall Thermostat.

Disconnect the Thermostat Wiring at the Furnace (at least the Red wire)

and try again.

You could wire in an external Fuse Holder...

click on picture

[delawaredrew]

That makes some sense. I did disconnect the thermostat at one point. The indicator on the board did light up as normal, but it blew the fuse as soon as I wired it back in and asked it to heat. I also tried to just cross the red and white at the board, which also blew the fuse when I powered it up. I wasn't sure what to make of it or if that was a bad thing to do.

If that fuse is on the 24v circuit at least it gives me something to check. I can check that for 24v, maybe that'll tell me something. Maybe the transformer is bad on the board, which still means a new board but it would be nice to know.

It does have a heat pump style thermostat, with 2 mercury switches, and way more internal wiring than a simple gas furnace needs.

[RegUS_PatOff]

Transformer sounds OK

and that would be 24v AC

disconnect the Thermostat wires and do some OHM meter tests on those wires

and on the Furnace connectors.... Gas Valve

OR there's a pinched/shorted wire to the Thermsostat or on the Furnace

 

[ACtechGUY]

The problem you describe almost always comes from shored thermostat wires. Check the wiring at the low voltage terminal strip very closely. you have likely shorted the W wire to the C wire in the course of looking for your ignition problem Or You may have pinched one of the wires by sitting or standing on it.

To verify where the problem is detach ALL wires from terminal strip.

install jumper wire from W to R . If the fuse does not blow the problem is in the wires(likly right near the furnace).

If it blowes the fuse , then you have a short to ground in the furnace safty circuit. maybe a misplaced wire?

[delawaredrew]

[user=57399]ACtechGUY[/user] wrote:

The problem you describe almost always comes from shored thermostat wires. Check the wiring at the low voltage terminal strip very closely. you have likely shorted the W wire to the C wire in the course of looking for your ignition problem Or You may have pinched one of the wires by sitting or standing on it.

To verify where the problem is detach ALL wires from terminal strip.

install jumper wire from W to R . If the fuse does not blow the problem is in the wires(likly right near the furnace).

If it blowes the fuse , then you have a short to ground in the furnace safty circuit. maybe a misplaced wire?

Thanks for the advice guys, this hasn't been high on my list as it isn't cold here yet, (or ever really) but I want to get back under there and figure it out this week.

I'll check out the wiring, it runs straight up out of the unit it a wall but I may have crimped it or otherwise messed it up while wriggling around under there.  It blew the fuse before I had any reason to be in the blower compartment where the control is, I did have the ignitor out already, so maybe I did something in that area.

Would a bad pressure switch cause an issue like this?  When I pulled the hose off to clear it out the hose was attached far more firmly to the pressure switch than I expected and required a bit or persuasion to slide off, maybe I damaged the diaphragm or something, or shorted a wire there.

Just so I am clear as to what the 24v circuit is doing:  does the board put 24v out on the W or R?  I assume one sends 24v up and the other returns?

[ACtechGUY]

The pressure switch is not an issue unless one of the wires is touching the metal of the unit or pressure switch. The pressure switch is just that( a switch) if the wires touch together the worst that will happen is the furnace will not fire.

You can measure 24 volts AC between R and C at the board. the 24 volts "hot" side of the transformer is "R" . The R terminal feeds the themostat. The thermostat then switches back differnt 24 volt outputs depending on the mode and what the stat is calling for.

R= 24 volts to thermostat

G= thermostat 24 v output to furnace to turn on fan

W= thermostat 24 v output to furnace to turn on heat

Y= thermostat 24 v output to furnace and condensiong unit to turn on cooling

All these readings are to the "C" terminal

R to C =24 volts AC

G to C "

Y to C "

W to C "

When you disconnected the ignitor , maybe you plugged back ta wrong wire that you knocked loose near the ignitor?

[RegUS_PatOff]

[user=22175]delawaredrew[/user] wrote:

.. does the board put 24v out on the W or R?  I assume one sends 24v up and the other returns?

as shown on the wiring diagram posted,

the 24v AC goes out the Red wire to the thermostat, and returns on the White wire.

It could also come back on the Green (Fan ON)

and Yellow (COOLING)

it shouldn't be connected or touching the C terminal

[delawaredrew]

Thanks.  Only R and W here.  That does explain why the fan only switch never worked too.

Still trying to find time to go down there and see what I can find out;  after I replace the starter in my truck and take care of my gf who just broke her arm and needs surgery... what a freakin' week so far!

[RegUS_PatOff]

If it only uses Red and White

(heat only, no cooling, no Fan control)

then IF there was a short across Red to White, it wouldn't blow the Fuse,

it would just turn the heat on continuously.

Unless either of those wires was shorted to ground.

 

Disconnect all of the external Thermostat wires form the Furnace Terminal Strip,

while making sure neither wire is shorted/pinched to chassis (ground)

and also, not touching the C terminal

 

 

[delawaredrew]

Hi guys,

Good and bad news on the furnace.  The good news is that it is running as I type this, heating normally so far.  The bad news is I have no idea what I did to fix it!

I went under the house with all tools and meters and all, all the stuff I use to do appliances; expecting to be cursing loudly and very puzzled before long.  I can't curse at work so I tend to get it all out during work around the house.

Before reapplying power I checked out all 3 TCOs, the ventor motor, gas valve, anything that I could get my probes on.  Everything seemed to check as expected.  The pressure switch was a little bit of a puzzle, as I could hear air escaping as I blew into it's hose.  The hose is fine but the switch definitely allows air to pass through it. Not something I expect from the type of water level/pressure switches I see on washers so I wasn't sure what to make of that.

So... I disconnected the 2 thermo wires replaced the 3a fuse and  got a nice slowly flashing green light.  The Red wire is carrying 27v, White has continuity to ground, both on the board and after it passes from the unit.  again that puzzed me but I went ahead and crossed them and, voila!!!!  It started right up, previously that had blown the fuse?  WTF?

I reconnected the thermo, had my gf turn it on inside and it started back up as normal.  It has just turned off, at the set point.  Wish I knew what I did but I'll take results over skill on this one!

Thanks for the advice!

[Budget Appliance Repair]

As far as the pressure switch leaking air when you are blowing into it, that is normal.

There is a very small air bleed hole at the base of the hose attachment stub, I believe it is to keep from putting to much pressure on the switch diaphragm.

[delawaredrew]

Thanks budget, I was curious about that.  I figured it must be like you said instead of the switch having a leak or the control wouldn't read enough combustion airflow to start. 

Any thoughts on the 27v output to the thermostat?  Spec is 24v I hear.  10-15% over voltage seems a little much for a healthy transformer.

[Budget Appliance Repair]

[user=22175]delawaredrew[/user] wrote:

Any thoughts on the 27v output to the thermostat?  Spec is 24v I hear.  10-15% over voltage seems a little much for a healthy transformer.

Is the 27 volt reading without the load attached?   Even if with load attached it's not uncommon to see secondary side of a 24 volt rated transformer putting out anything between 24 and 28 volts.

[delawaredrew]

Yeah 27v with no load, nothing connected.

It has been fine so far so whatever I did I must have done correctly.

Thanks for the help, the voltage was a lingering ? so if that isn't odd I am happy with the furnace.

[JJDH]

[user=36]Budget Appliance Repair[/user] wrote:

As far as the pressure switch leaking air when you are blowing into it, that is normal.

There is a very small air bleed hole at the base of the hose attachment stub, I believe it is to keep from putting to much pressure on the switch diaphragm.

Little hole is a moisture vent.

[ACtechGUY]

Regarding the diapham...... it DOES NOT work on positive pressure . It senses Vacume. The way to verify a diapham and it's switch are functioning is to suck on the tube, not blow in it. You are probably lucky you didn't damage the diapham by blowing into it:shock:.

About the 27 volts. Transformer output voltage is a direct result of input voltage and the load on the transformer. You probably have a high 120 volt input. If you have 115 volt in you might get 24 volts out. if you have 125 volts in you might get a higher volt out like 27 volts. Also if you had componets actively powered by the transformer you would see a lower voltage.

Your furnace will likely work just fine now... you probably shifted that shorted to ground connector or wire back into the correct position when you checked all your devices.

Your original problem sounds like it WAS related to the pressure switch being clogged , You might just be ok now.

[delawaredrew]

Thanks for the voltage info.

The info about the pressure switch answers a few questions, as it enters the ventor fan housing behind its blades. I had wondered how it built up enough pressure to affect the switch in that position.

I learned the hard way on a washer years ago about being gentle with diaphragm switches so I didn't apply much force by mouth, the drain or bleed hole must have saved me from my ignorance.

It is working fine now, but I would like to know what caused the fuse to blow repeatedly. I'm guessing there is a short somewhere in the short section of thermo wire leading out of the unit, nothing that I can see there but maybe it is under the insulation and shorting to one of the unused colors.