Nordyne MMHA-070ABHR-01 - Pressure switch location
#1
12-27-18, 09:22 PM
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Nordyne MMHA-070ABHR-01 - Pressure switch location
When the heat is turned on, the blower motor instantly kicks in and circulates cold air. The inducer motor does not turn on and I am receiving a two flashing light code, which I have found to mean "Pressure switch is closed with inducer on".
I know where the inducer motor is and went with replacing that. Still receiving the two flash code after replacing the motor, so I believe it might be a bad pressure switch. Does anyone know if that is my problem and where to find the switch?
I know where the inducer motor is and went with replacing that. Still receiving the two flash code after replacing the motor, so I believe it might be a bad pressure switch. Does anyone know if that is my problem and where to find the switch?
#2
12-27-18, 09:55 PM
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I don’t believe you have one. I think that furnace has a centrifugal switch in the inducer motor.
The switch should close when the inducer runs
The switch should close when the inducer runs
#3
12-28-18, 06:39 AM
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Thanks for the information roughneck77, i'll take a look into the centrifugal switch and will provide any updates
#4
12-28-18, 11:53 AM
Group Moderator
Welcome to the forums.
The black two wires on the draft inducer motor are power.
The two red wires coming off the draft inducer motor are the switch leads.
The switch should be normally open and then close when the inducer motor is running.
The black two wires on the draft inducer motor are power.
The two red wires coming off the draft inducer motor are the switch leads.
The switch should be normally open and then close when the inducer motor is running.
#5
12-31-18, 08:03 AM
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Thanks for the information, I was able to get the inducer motor to start up correctly. I now can get the heating process started but after the initial call for heat, the blower fan will kick on after the inducer motor has done its thing but will then shut off after about 30 seconds. Then after another 30 seconds, the blower fan will kick on again and then turn off. Repeating the process until I kill the call for heat, and even continuing after the call for heat is killed. The four suggested issues are:
- Ductwork that is leaky or designed poorly
- A furnace that is oversized for the home
- Abnormally low temperatures in the heat exchanger
- Abnormally high temperatures in the heat exchanger
#6
12-31-18, 08:38 AM
Member
This is the indoor blower, correct?
Is the blower getting a constant power supply? Or is something opening and closing causing the blower to cycle?
Is the blower getting a constant power supply? Or is something opening and closing causing the blower to cycle?
#7
12-31-18, 09:03 AM
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Correct, indoor blower. I believe power supply to the blower is just fine. The AC works just fine, I can also place the fan into the 'On' mode and it will run without any issues.
Going to test the fan limit switch today. Got a couple pages up with some notes, will try when I get home today and will update the thread. Thanks
Going to test the fan limit switch today. Got a couple pages up with some notes, will try when I get home today and will update the thread. Thanks
#8
12-31-18, 10:39 AM
Group Moderator
Your are not losing the burner so it is not overheating.
Your fan switch should be inside that metal box behind the ignition module.
It uses a standard F115-30 switch...... Part # 626337R
Just an example. Available many places.
Fan switch
Your fan switch should be inside that metal box behind the ignition module.
It uses a standard F115-30 switch...... Part # 626337R
Just an example. Available many places.
Fan switch
#9
12-31-18, 04:30 PM
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PJmax - thank you, that saved me time looking for the thing. Gave it a test, and sure enough its dead. Model is 6262792, I was able to find a direct replacement;
https://mobilehomepartspro.com/produ...yne-pn-626279/
My unit has two switch, I believe the second one is the high limit switch. Its model is 626337B
I'll update the thread once I have the replacement part and its installed
https://mobilehomepartspro.com/produ...yne-pn-626279/
My unit has two switch, I believe the second one is the high limit switch. Its model is 626337B
I'll update the thread once I have the replacement part and its installed
#10
01-09-19, 09:00 AM
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Hey everyone, thank you again for the assistance provided. Had to just go with replacing the unit, it was 25 years old and one issue was just leading to another. Replaced the limit switch and that corrected the blower issue, but then started having trouble with the circuit board. Go figure. Anyways, my unit is technically repaired as it is gone. Thanks again
#11
01-09-19, 09:44 AM
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