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Changing out st9160 to st9120 furnace board, where do m1 and

Customer Question
changing out st9160 to st9120...
changing out st9160 to st9120 furnace board
JA: Did you check the furnace's filters?
Customer: where do m1 and m2 as well as yellow and blue off transformer on blower fan connect to
JA: Do you plan on doing the work yourself?
Customer: I am in the middle of it
JA: Anything else we should know to help you best?
Customer: I have these four wire that were connected to old board 9160 not sure where on 9120 to plug into
Submitted: 1 year ago.Category: HVAC
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Answered in 3 minutes by:
10/22/2016
HVAC Technician: airheatman, HVAC Technician replied 1 year ago
airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8,527
Experience: Furnace, A/C and heat pump specialist.
Verified

I will be happy to help. Let me grab a manual

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HVAC Technician: airheatman, HVAC Technician replied 1 year ago

M1 and M2 are unused on the 9120. They can be taped off, They are unused motor speeds.

The yellow and blue that went to 24VAC will go to X and COM to C

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Customer reply replied 1 year ago
The terminals are on what part of board
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

If you have further questions, please let me know.

Thanks for letting me work with you.If my answer has been polite, professional,and thorough, please click one of the ratings before you go. If you still need help let me know!.Expert is not paid for assisting you until you rate answer.Feel free to follow up for 30 days at no additional cost. Bonus always appreciated if you feel justified.

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Customer reply replied 1 year ago
Yellow to c or X
Blue to X or c
Not sure
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

Normally blue is C, If you do not remember give me model on furnace and I will see if I have a diagram if there is not one on furnace

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Customer reply replied 1 year ago
Furnace still is not starting
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

Do you have a volt meter so we can troubleshoot? And do you have door switch held in ?

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Customer reply replied 1 year ago
I sent the phone request in make it quicker and easier does it go to you?
Customer reply replied 1 year ago
I have a volt meter ready
Customer reply replied 1 year ago
Says phone call not available
Ok
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

Start by checking 120 volts into transformer and 24 volts out.

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Customer reply replied 1 year ago
Still there
Customer reply replied 1 year ago
Sorry need more coaching
White and black test board power on?
Unplug yellow and blue at board?
Customer reply replied 1 year ago
Power on red to L1 black to black on six pin shows nothing
Customer reply replied 1 year ago
Main switch is on
I hear humming
Customer reply replied 1 year ago
Status light is flashing on board
Customer reply replied 1 year ago
Led on gas valve unit is flashing too
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

See the drawing I made, Check between white Neutral and Black L1

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Customer reply replied 1 year ago
On V with solid bar nothing
On V with wave bar 35
On yellow blue
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

Not sure what you are referring to.L1 and Neutral are on control board

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HVAC Technician: airheatman, HVAC Technician replied 1 year ago

OK I understand you are referring to the meter. The V with squiggly bar is correct

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HVAC Technician: airheatman, HVAC Technician replied 1 year ago

Tell me black to white on L1 and N and tell me between yellow and blue at C and X

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Customer reply replied 1 year ago
I put red meter tip on black wire on L1 then black meter tip on black within 6 pin the black wire is coming from the transformer no reading present to check for power from board to tansformer
Customer reply replied 1 year ago
Really appreciate the help told (wrongly) this is a a plug and play replace the board
Customer reply replied 1 year ago
Sorry meter set at 200 put black on L1 and red on neutral white wire reading is 157
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

That is high. How about between C and X?

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Customer reply replied 1 year ago
Is at 35
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

OK you have an electrical issue.WE can not have over 127 in and 28 out. Check a nearby recetcle or in breaker panel

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Customer reply replied 1 year ago
The furnace is on its own dedicated breaker still moved it to an empty new breaker same readings
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

How about other outlets in the house see if they read that high

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Customer reply replied 1 year ago
Just tried a couple yes same ...
Meter of out of calibration
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

Either meter is out of calibration or high voltage is the problem. Board can not handle 157 volts

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Customer reply replied 1 year ago
Must be meter (between 10-15 years old )
If it was that bad would have lost electronics by now
What else to check for,
Customer reply replied 1 year ago
worked
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

OK tell me about the valve What is furnace model and valve number and what is the light doing

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Customer reply replied 1 year ago
Furnace is a keep rite
Model n8mpno75b12a1
Manufactured Aug 2004
By international comfortHoney well valve says replace only with model sv 95541
Green led flashing on off 30 seconds with a hum
Then turns off flashing error codeGreen led flashing
Customer reply replied 1 year ago
Have left thermostat on calling for heat
Error code I'd 3 flashes the pause
Customer reply replied 1 year ago
Inducer fan not turning on when humming either
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

OK the 3 flash erorr is an open pressure switch because inducer is not coming on to close it. Next check for 120v to inducer fan on call for heat

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Customer reply replied 1 year ago
No power on volts going through black & white wires to inducer fan
Also tried a continuity test with both terminals got zero just like crossing pins on the meter
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

Tap on pressure switch,The remove hose from inducer and suck and blow on hose to see if switch is opening and closing.Then retry

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Customer reply replied 1 year ago
Blew and ducked on hose can hear valve inside clicking
Checked for power from gas valve (two blue) power there
Customer reply replied 1 year ago
What should I check next
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

Unplug wires to pressure switch , suck on hose to switch and check continuity across switch.Make sue it has no continuity when not sucking on hose and we get continuity when sucking.

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Customer reply replied 1 year ago
When ducking zero on ohm meter
When not get one on ohm meter
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

OK now do same with wires connected. but just make sure the switch is open.It will not close unless inducer starts

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Customer reply replied 1 year ago
Did the same sucking with wire connected
Ohm meter almost got to zero ran out of ability to suck any more in
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

OK not sure why but the board is not sending signal to the fan. Since the pressure switch is open the board should send 120 to fan as soon as you call for heat.

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Customer reply replied 1 year ago
What's next sir
HVAC Technician: airheatman, HVAC Technician replied 1 year ago

That is about as far as I know to go without actually being there. I can open to other experts if you would like

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airheatman
airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 8,527
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Experience: Furnace, A/C and heat pump specialist.

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