Amana AMH951155DXAA open high limit without heat turning on
#1
03-30-18, 08:02 AM
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Amana AMH951155DXAA open high limit without heat turning on
Hi,
My blower was continuously on for (had been running for hours). I reset the furnace by turning of the power. Upon turning it back on I checked the error code. 4 flashes ..open limit. I checked all for limit 2 high limit and even 2 roll out limit. All have continuity. I jumped all 4 to test. Still same error code. Wiring diagram shows 3 limit switches but I only found 2
the error code and fan blower is on as soon as I turn on the power to the furnace. I also switched th control board because it had a loose connection
any ideas what could be causing it
My blower was continuously on for (had been running for hours). I reset the furnace by turning of the power. Upon turning it back on I checked the error code. 4 flashes ..open limit. I checked all for limit 2 high limit and even 2 roll out limit. All have continuity. I jumped all 4 to test. Still same error code. Wiring diagram shows 3 limit switches but I only found 2
the error code and fan blower is on as soon as I turn on the power to the furnace. I also switched th control board because it had a loose connection
any ideas what could be causing it
#3
03-30-18, 09:35 AM
Group Moderator
Welcome to the forums.
You replaced the board and still have the same problem ?
You need to check the limit circuits right at the control board 12 pin connector.
One circuit is pins #1 and #7. The other circuit is pins # 5 and #11.
There should be 0v across either set of pins on the connector.
I also switched th control board because it had a loose connection
You need to check the limit circuits right at the control board 12 pin connector.
One circuit is pins #1 and #7. The other circuit is pins # 5 and #11.
There should be 0v across either set of pins on the connector.
Last edited by PJmax; 03-30-18 at 03:53 PM.
#6
03-30-18, 10:18 AM
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If you mean furnace powered..... yes. There won't be any power to measure for if it's off. You are looking for no voltage across the pairs of pins I listed with the plug in place. Doesn't need to be calling for heat.
#7
03-30-18, 12:53 PM
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Originally Posted by PJmax
Welcome to the forums.
You replaced the board and still have the same problem ?
You need to check the limit circuits right at the control board 12 pin connector.
One circuit is pins #1 and #7. The other circuit is pins # 8 and #11.
There should be 0v across either set of pins on the connector.
You replaced the board and still have the same problem ?
You need to check the limit circuits right at the control board 12 pin connector.
One circuit is pins #1 and #7. The other circuit is pins # 8 and #11.
There should be 0v across either set of pins on the connector.
1 and 7 0v
8 and 11 27v
#9
03-30-18, 01:48 PM
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That limit loop shows as two manually resetable limit sensors. More than likely one of the two flame rollout switches over the burner has tripped. They should have a little red button on them for resetting.
#11
03-30-18, 02:11 PM
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Then you need to trace the wiring that connects pin #8 to #11. Something in that loop is open. It's hard to tell from looking at the service manual as it only shows a generic circuit diagram. The actual diagram is usually posted on the back of the blower door,
#12
03-30-18, 02:24 PM
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Originally Posted by PJmax
Then you need to trace the wiring that connects pin #8 to #11. Something in that loop is open. It's hard to tell from looking at the service manual as it only shows a generic circuit diagram. The actual diagram is usually posted on the back of the blower door,
the wiring diagram is torn ..
the rollout switches are orange and red with a pink wire connecting them
it looks like I should have checked pin 5 ...
across pin 5 and 11 .. 0v
#14
03-30-18, 02:39 PM
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This is my user manual .. by comparing what's left of the diagram on the furnace with my manual it looks identical
#15
03-30-18, 04:09 PM
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My apologies. On my manual it looks like an 8. You are correct..... it is a 5. I've changed my original post.
#16
03-30-18, 04:17 PM
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Originally Posted by PJmax
My apologies. On my manual it looks like an 8. You are correct..... it is a 5. I've changed my original post.
but across the correct pins I get 0v ... could the thermostat or w1 wire be the cause of the error message and fan running continuously?
in the diagram it shows the limit circuit connecting to the w terminal ... it's in the upper right corner of the diagram
#17
03-30-18, 04:33 PM
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Pin 7 coming out of the board should be 24vac when measured to common. After is passes thru the limit switches it should present 24vac to the W1 terminal as long as the stat is not calling for heat.
#18
03-30-18, 04:58 PM
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I ended up wiring the furnace direct and it works ... so the problem lies with the wires or the thermostat
#19
03-30-18, 05:01 PM
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The Nest has a long reputation of causing equipment problems.
Is this wired up for power stealing, or does the Nest have a common?
Is this wired up for power stealing, or does the Nest have a common?
#20
03-30-18, 09:16 PM
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Originally Posted by roughneck77
The Nest has a long reputation of causing equipment problems.
Is this wired up for power stealing, or does the Nest have a common?
Is this wired up for power stealing, or does the Nest have a common?
It was only connected with g w y r1 no common
#21
03-30-18, 09:22 PM
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Furnace works fine with old thermostat
I don't understand what happened ... it was working fine for almost a year ... only change was I connected my humidifier aprilaire 700 it worked for a few days without issue ..
it had never worked .. I wired it without the humidistat ... it had some kind of loose connection so I connected valve directly to pressure switch and c on board .. it would only run when calling for heat .. but had 24v even if there was no call for heat .. but like I said it ran fine for a few days
I don't understand what happened ... it was working fine for almost a year ... only change was I connected my humidifier aprilaire 700 it worked for a few days without issue ..
it had never worked .. I wired it without the humidistat ... it had some kind of loose connection so I connected valve directly to pressure switch and c on board .. it would only run when calling for heat .. but had 24v even if there was no call for heat .. but like I said it ran fine for a few days
#22
03-30-18, 09:58 PM
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Not sure I'm following you on the humidifier. Is that an older Aprilaire 700 ?
Almond or gray case ?
The older almond colored 700's need a relay for a nest connection.
Almond or gray case ?
The older almond colored 700's need a relay for a nest connection.
#23
03-30-18, 10:26 PM
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It's the older unit ... almond case ...
I bypassed the humidistat.... I connected the a the humidifier's solenoid harness directly to the pressure switch using the brown jumper cable and the c spot on the control board
My humidistat works intermittently.. so I decided to by pass it as my house is in the 20s% for humidity
the humidifier worked for a few days then I started having the issues with the Limit switch circuit (thermostat ended up being the issue)
I bypassed the humidistat.... I connected the a the humidifier's solenoid harness directly to the pressure switch using the brown jumper cable and the c spot on the control board
My humidistat works intermittently.. so I decided to by pass it as my house is in the 20s% for humidity
the humidifier worked for a few days then I started having the issues with the Limit switch circuit (thermostat ended up being the issue)
#24
03-31-18, 12:14 AM
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Your older 700 has it's own built in 24vac supply. You cannot connect those two leads directly to a furnace or a nest. Connecting it to your nest probably caused the problem/damage. To confirm this..... short the two leads coming out of the humidifier..... it it starts..... it will need a relay to be connected to the furnace or the nest.
#25
03-31-18, 03:41 AM
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I will try that ... it does have a transformer but it was connected to it separately... I purchased the homme 4 years ago .. it had never worked I did change the sensor relay ... which is why I tried connected it directly to the c terminal and pressure switch on the furnace bypassing the humidistat 56
#26
03-31-18, 05:21 AM
Member
It is not permitted to tie into the furnace safety switch loop like that.
Connections for humidifiers and other accessories should be done via the low voltage control connections.
Connections for humidifiers and other accessories should be done via the low voltage control connections.
#27
03-31-18, 07:55 AM
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Originally Posted by roughneck77
It is not permitted to tie into the furnace safety switch loop like that.
Connections for humidifiers and other accessories should be done via the low voltage control connections.
Connections for humidifiers and other accessories should be done via the low voltage control connections.
I followed these directions
