How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask M Oglesby Your Own Question
M Oglesby
M Oglesby, HVAC Technician
Category: HVAC
Satisfied Customers: 2038
Experience:  Universally Certified HVACR Technician
27079509
Type Your HVAC Question Here...
M Oglesby is online now
A new question is answered every 9 seconds

My furnace error code says my limit switch is open and should

This answer was rated:

My furnace error code says my limit switch is open and should be closed. I am looking for the limit switch and trying to reset, but no luch yet. Any help?

M Oglesby :

There are two kinds of limit switches.

M Oglesby :

The first that we will try to locate is the Main Limit Switch so we can bypass it.

Customer:

ok

M Oglesby :

It is a rectangular or square looking device that has two wires attached to it and is usually located inside the furnace cabinet and sits on the back panel wall just above the gas valve. Locate it and let me know when you find it.

M Oglesby :

It is usually about 2 inches X 3 inches.

Customer:

i see the gas pipe coming in, and it comes to a circular silver looking thing that also has the on/off switch on it, is that it?

M Oglesby :

No that is the gas valve.

M Oglesby :

Look behind the gas valve on the back panel wall inside the furnace cabinet.

Customer:

on the back panel there is a black plastic, about 2X3, thing with two wires coming out of it, but there doesn't seem to b3e any switches or anything on it

Customer:

one red and one white wire if that helps any

M Oglesby :

does it have any writing on it?

Customer:

yes, looks like a upc code and some other serial numbers and that type of stuff

Customer:

can i send a picture on this?

M Oglesby :

Yes you can.

M Oglesby :

Can you tell me the numbers that is written on it?

Customer:

012 on the side...

Customer:

0344r...

Customer:

025-29041-012

Customer:

1nt17L-2623

Customer:

L190F-30

M Oglesby :

That is it!

Customer:

i'm a genius

M Oglesby :

Remove the two wires from the Main Limit Switch and attach them together metal to metal or use a piece of wire to jumper them together.

M Oglesby :

While they are attached, turn the heat on.

M Oglesby :

Let me know if the heat comes on or not.

Customer:

will any old wire do?

M Oglesby :

It should work. Just make sure it is stripped.

Customer:

ahhhh, i see glow coming from the conbustion chamber

M Oglesby : Did the burners ignite?
Customer:

yes they did, thank you. now do i have to do something as a permanant fix, or is this permanant?

M Oglesby : No that is not permanent.
Customer:

perfect, thanks

M Oglesby : That means you need a new Main Limit Switch.
M Oglesby : You can get one here at www.AmericanHVACparts.com
Customer:

can i just get one of those at home depot or anyting

Customer:

ok perfect

M Oglesby : Great Job! You just saved yourself $200
Customer:

sweet, thanks

M Oglesby : You are welcome. I hope you remember me in the Bonus!!
Customer:

oh i will

M Oglesby : Please hit ACCEPT if you are satisfied with this answer. Bonuses and positive feedback are very much appreciated! Thank you very much!
M Oglesby : Great Job again!
M Oglesby and 2 other HVAC Specialists are ready to help you