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M Oglesby
M Oglesby, HVAC Technician
Category: HVAC
Satisfied Customers: 2038
Experience:  Universally Certified HVACR Technician
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What does York furnace limit switch error 4 flashing red indicate?

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My York LY8S furnace is flashing 4 red code."Open Limit Switch" the troubleshooting guide says this is dirty filters. The filter has been replaced but still flashes 4-red.

Is there a reset? The auxillary fan works and the blower motor seems to be working fine but no flame/heat.

M Oglesby :

There may be a manual reset rollout limit switch that is open. The rollout limit switch is a small round metal disc looking device that has two wires attached to it and a small red button on top of it. They are usually located around the burner tray inside the furnace cabinet. There may be more than one.

Try to locate them and press the little red button in. Let me know if you find them.

JACUSTOMER-5rdz86v3- :

There are three, one on top and one on each side....the top on clicked when I pressed it...still same error.

M Oglesby :

Turn the power off then back on to see if this resets the board, then try to call for heat.

JACUSTOMER-5rdz86v3- :

Can this be done by the door switch or do I need to switch the breaker

M Oglesby :

Switch the breaker.

JACUSTOMER-5rdz86v3- :

Didn’t do it

M Oglesby :

Ok the main limit switch must be open. It is located on the back panel wall inside the furnace cabinet. It is rectangular and has two wires attached to it. Let me know when you locate it.

JACUSTOMER-5rdz86v3- :

It has a red wire on one plug and two whites off the other plug? 1NT17L on the label?

M Oglesby :

Usually they only have two wires attached to them but let’s try to bypass it.

JACUSTOMER-5rdz86v3- :

Ok

M Oglesby :

Remove the two wire leads and attach them together metal to metal. Let me know if the error code remains the same.

M Oglesby :

Make sure to attach them very good.

JACUSTOMER-5rdz86v3- :

That did it. Is it safe to keep that bypassed or what’s next?

Hello? Anyone there...its been 45 minutes?

M Oglesby :

That means that switch is bad and needs to be replaced. Ok to temporarily bypass but not for long.

Thanks!

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