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When you shut off power and turn back on, does it go straight to blinking?
What all limits did you test and how did you test them
when this first happened was the filter plugged?
Ok we are going to eliminate one at a time.
Number 11 on the chart I sent HEREPower oiff...remove the 2 wires, connect direct together (a small nail, staple or paperclip inserted into each wire end connector works well).
with wires connected directly together turn power on and tell me code.
Look for the blue hilights
thank you....now we want to move to the rollouts......follow the wires from the limit you just checked. The wires will leapfrog to limits before returning to circuit board...we want to check all these...the roll outs by the burners have tiny reset buttons in center.
Also if you can post a pic of your furnace with doors off I can draw locations for you
If you follow the wires from the safetys you have found...do any of the wires lead to the blower (bottom) compartment
did you bypass the switch as described earlier?
yes...but have you been jumping each limit the same way to eliminate?
we will not jump anything except the limit switches...no blower wires..
Post pic of where the wires from phenolic go to blower section
Yes....when a limit is open the main blower runs by default
ok imagine this...
The circuit board has a wire that leaves it on the the way to the "limit" loop. It goes through each limit leap frogging until finally the wire returns to the circuit board. Somewhere in the loop is an open contact.
I need to follow the wires safetys until you cover everything in that loop....
everything in that loop one at a time...until the light goes solid
have to sign off for a while, but will repsond as soon as I can.
Let's do this.SINCE WE ARE GETTING A LIMIT ERROR> Note there are 2 blue wires leaving the 9 pin plug on board. One leaves board and goes through all limits and then returns to board proving the circuit is closed. Unplug the 9 pin plug and stick the leads from your meter into the unplugged harness between pins 3 and 8 and see if we have continuity.That will tell us if there is an pen limit in the circuit or not.
Are you sure you found them all? rollouts near burners,main limit in furnace vestibule exhaust vent and on blower housing are likely places you may have them.I would start at board and visibly trace blue wire to verify all the way back to board.Most likely overlooked is one in blower housing.
OK the reason you get no reading on orange orange is because the pressure switch is "open".It does not close until inducer motor comes on. Yellow brown are low voltage out to gas valve.
You have to have a break somewhere in the blue wire if you do not get continuity between the blues. Until we get continuity, board is not going let 24v go to the valve.
Next I would put one meter probe into one of the blues on socket.Then leaving it there. Go to every limit in circuit and check both sides until you find where we do not have continuity.(Note touch leads together first just to veirfy meter is working)
We have to find the break.If you want to prove this is the issue.(if you have a couple of wire nuts) cut the blue wires just outside the 9 pin and connect the ones from the plug together just for a test to see if furnace works. Of course this is only for a test and you will need to reconnect correctly.
It really makes no difference They are all in series.Remember the old Christmas bulbs where if one went out, they all went out? THis is about the same. That blue has to leave board go through all limits and come back.
AS state, it can go through any one first as long as it goes into one ,then out to next through each one,but I usually wires per mfgr diagram.Lets check the one on blower.They are known to fail.
Take your time. AS mentioned if you don't mind a wire connector you can cut the blue wires to and from and tie them together to see if that is the problem
Blower should be on before a minute. Try again and as soon as burners light , put meter leads on Neutral and HEAT terminals on board and watch for voltage. Within about 30 seconds we should het 120v between those terminals.
You could also have a board failing or loose connection from all we have done.Inducer should keep 120 all the time. Check and make sure wires are making good connection from inducer to board.
Well we know that switch you bypassed and made it work needs to be replaced.
My bad, I thought you had bypassed the one on blower.Let me know if furnace works now
If inducer motor is still cutting in and out we need to determine if the power is being lost from board or not.If so, Try bypassing thermostat by connecting R and W (where thermostat wires connect)on board and see if it will stay on
Wires you want to check at inducer for 120 to see if cutting in and out here.
AS for bypassing thermostat R and W as shown here
With R and W jumped at board thermostat is out of picture so it will make no difference what it is set to. If you do not get 120 out of board to inducer with R and W jumped, we should still get a code .
This s sort of sounding like you may have another bad board.I am going to open to other experts to see if they have ideas.