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It is blinking 3 times, it says the limit switch is open,

Customer Question
It is blinking 3...

It is blinking 3 times, it says the limit switch is open

Contractor's Assistant: I'll do all I can to help. How long have you been dealing with this?

Last night it was cold in the house, I didn't think to look. I changed the filter today and it looks like maybe the pilit is out?

Contractor's Assistant: Do you plan on doing the work yourself?

The unit is only a couple years old

Contractor's Assistant: Did you double-check the thermostat? And what about the unit's filters?

I turned it up last night to 78 then 80. It stayed cool all night.

Contractor's Assistant: Anything else we should know to help you best?

The filter did need changed I'm sad to say I fell down on that this time.

Submitted: 6 months ago.Category: HVAC
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Answered in 5 minutes by:
1/5/2018
HVAC Technician: airheatman, HVAC Technician replied 6 months ago
airheatman
airheatman, HVAC Technician
Category: HVAC
Satisfied Customers: 9,175
Experience: Furnace, A/C and heat pump specialist.
Verified

The flash code is an open high temp limit error.
There may be
several limits on the furnace.Blow describes locations:
PRI***** *****MIT
The pri***** *****mit control is located on the partition panel and monitors
heat exchanger compartment temperatures. It is a normally closed
(electrically), automatic reset, temperature-activated sensor.
The limit guards against the overheating as a result of insufficient
conditioned air passing over the heat exchanger.
AUXILIARY LIMIT
The auxiliary limit control(s) are located on or near the circulator
blower and monitors heat exchanger compartment temperatures.
They are a normally-closed (electrically), manual-reset, temperature
activated sensors. These limits guard against overheating as a
result of insufficient conditioned air passing over the heat exchanger.
VENT DRAFGAURD
These would be located on the draft hood if you have one on your furnace.
ROLLOUT LIMIT
The rollout limit controls are mounted on the burner/manifold assembly
and monitor the burner flame. They are normally-closed
(electrically), manual-reset, temperature-activated sensors. These
limits guard against burner flames not being properly drawn into the
heat exchanger.
Lets start with the most simple and easy. Look near burners for limits with a little button in center.It will push in to reset.If none are tripped we will go from here. Let me know if you have a multi meter for troubleshooting.
http://i.imgur.com/CGkB9sa.jpg

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Customer reply replied 6 months ago
I don't have one. I don't see any buttons near the burners.
Customer reply replied 6 months ago
There is a red button right below
Customer reply replied 6 months ago
It has 2 red wires coming off of it
Customer reply replied 6 months ago
I pushed it but it's still blinking
HVAC Technician: airheatman, HVAC Technician replied 6 months ago

Follow the red wires and see if they go to more limits.There should be at least 2 or 3 more in the circuit before wire goes back to board.

If no buttons on limits try bypassing one at a time until we determine which is open.

https://i.imgur.com/WqmGzzO.png

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Customer reply replied 6 months ago
Ok there it another one on the top left but again nothing happened
HVAC Technician: airheatman, HVAC Technician replied 6 months ago

What is model on furnace? There may be one tucked away on blower housing that is often overlooked.

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Customer reply replied 6 months ago
I see model EZ-1625
Customer reply replied 6 months ago
Or would that just be the base
Customer reply replied 6 months ago
AbA 100 NI4R
Ser###-##-####
HVAC Technician: airheatman, HVAC Technician replied 6 months ago

Looks like furnace is made by an independent company Texas furnace, not much info available for me to pull a manual. Do you have a muti meter to troubleshoot to see if there is an open in the limit circuit?

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Customer reply replied 6 months ago
I do not
Customer reply replied 6 months ago
Where is the limit circuit?
HVAC Technician: airheatman, HVAC Technician replied 6 months ago

OK if furnace is saying we have an open limit we have to either trace that red wire from where it leaves board through limits until it comes back to board.That is considered the "limit circuit". If no limit is open the board is failing.

Can you attach a picture with both furnace panels remove standing back about a foot from furnace?

I was hunting a manual online but nothing available.Also if you can locate wiring diagram and sent a picture of it.

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Customer reply replied 6 months ago
There is a diagram on the cover panel would you like a picture of it also?
HVAC Technician: airheatman, HVAC Technician replied 6 months ago

THat would be great

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Customer reply replied 6 months ago
I was looking at that, does the "w" mean white
HVAC Technician: airheatman, HVAC Technician replied 6 months ago

W is the heat circuit from thermostat.When you call for heat, 24 volts comes from W at thermostat, through these limits, through the pressure switch and if all are "closed" continues to gas valve and energizes valve.

The error code is saying one of those limits is not closed.

TRy unplugging each and bypass it like this

https://i.imgur.com/WqmGzzO.png

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Customer reply replied 6 months ago
I'm going to ask a dumb question here, but what do I use to put in there ?
Customer reply replied 6 months ago
I mean will a paper clip or something like that carry the current?
Customer reply replied 6 months ago
Ok I did that with the two that plugged into the red push buttons did you also want me to do it with the one in the middle? The one that is one on a gray wire and one one red wire?
HVAC Technician: airheatman, HVAC Technician replied 6 months ago

Absolute. Or if you have a car fuse you can use it.

https://i.imgur.com/Aqd9O0f.png

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HVAC Technician: airheatman, HVAC Technician replied 6 months ago

Yes fo the one in middle too

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Customer reply replied 6 months ago
We still have the blinking light
HVAC Technician: airheatman, HVAC Technician replied 6 months ago

OK if all limits are closed make sure connections are good to board and if so It looks like board is giving false code.

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Customer reply replied 6 months ago
that means what?
HVAC Technician: airheatman, HVAC Technician replied 6 months ago

POints to a bad board , but hate to tell you to buy aboard without being there with a meter and putting my eyes on everything.I would probably get a local tech to verify before buying board as it could be something I can't see.

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Customer reply replied 6 months ago
really I'm no closer than I was an hour ago?
HVAC Technician: airheatman, HVAC Technician replied 6 months ago

You have proved the limits are closed and the board is saying they are open

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