Question about FACTORY AC PARTS Limit Switch Double Pole L150 Direct Replacement For Rheem Ruud Weatherking Oem Part 47-20045-02

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Ever limit switch i changed in my Weatherking furnace, it breaks the switch, what could cause this?

I have a Weatherking and for some reason the furnace stopped working today, so i go check the furnace and the two i have, one for each side of my duplex, it ended up not working, so i decide the way to figure it out was the flashing green light, gave out 3 flashes and a 2 second pause. I switched parts slowly and it worked on my other furance everything but the limit switch, when i switched the limits the furnace tht works stopped so i assumed it was that and tried it on my furnace that wasn't working and it ended up breaking tht limit switch aswell.

Posted by Tom G on

  • Tom G
    Tom G Jan 03, 2016

    How to i get the model number? Is it in a specific location



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Al Kizina

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You need the model number of the furnace to determine what the flashing light is telling you. Many times the part that looks to be at fault is not the true fault in the furnace. A slow running blower could cause the limit switch to trip. The circuit board tells you that the limit tripped, but the real cause is the motor or clogged filter.

Posted on Jan 02, 2016


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Who knows? You gotta post a video of your furnace so we can see what you got. Here is the sequence of operation of a late model furnace. they all basically work the same way. They have a draft inducer fan that causes a vacuum in a small hose leading to the pressure switch. If the board reads negative pressure it know the draft motor is working and pulling a draft it then cause the ignitor to kick in and after a minute opens the gas valve. It wait a sec to verify flame with the flame sensor and then if that flame is there it keeps burning and after 30 more seconds the fan kicks in.
Most of the time if the ignitor ain't workin it is either bad or a limit has tripped due to some sort of overheat problem like birdnest or cobwebs and such.

If you need further help, reach me via phone at

Oct 05, 2012 | FACTORY AC PARTS Furnace Spark Ignitor...

1 Answer

Furnace blinks 4 times indicating limit switch

Hello, a limit switch can open for several reasons, this could be due to dirty air filter, dirty blower wheel, blower motor not running at proper speed. Anything that cuts down on the airflow and causes tne heat exchanger to get way to hot will cause the limit switch to open.

Apr 16, 2011 | Heating & Cooling

1 Answer

Bryant 340mav036080 limit switch reset time

The primary limit switch in your furnace is an "automatic reset" switch, and should reset itself within a few minutes.

It is a safety device designed to prevent your furnace from overheating. If the furnace does get too hot, the limit switch opens and the burners turn off. The blower should continue to run until the furnace cools down again. The limit switch should then reset itself (usually less than five minutes).

If it will not reset, try tapping on the switch with a screwdriver or other tool. This will often un-stick it. If this does not work, the switch has failed and must be replaced.

A furnace will overheat for many reasons, but the most common are a dirty air filter (should be changed every 1-3 months), or a dirty evaporator coil (only if you also have central air). Make sure everything is clean and all your vents are open to help avoid this problem in the future!

There are other limit switches in the furnace as well, which are "manual reset". They will not reset unless the little red button on them is pressed. If one of these switches opens, it is best to call a contractor to evaluate your furnace, as an unsafe condition may exist.

Mar 02, 2011 | Heating & Cooling

1 Answer

Is the flame sensor for a weatherking 125000 btu at the top of the heat exchanger? i by passed this and furnace is working good now. i tried to clean re-installed and it still did the same thing! I think...

What you bypassed was the hi-limit switch. This is a most important safety control. If the furnace heat exchanger compartment gets too hot this control cuts (opens up) the electrical circuit to the gas valve and shuts the gas flow to the burners. After that little round disc cools down to a certain temperature it will close the circuit and your furnace will run again until it overheats and does the same cycle. There is a reason this control is tripping on you. Your furnace is overheating consistently for a reason. The first thing I would look at would be the air flow thru your system Is your air filter dirty?If is is very dirty you lose your airflow thru the heat exchanger compartment and the hi-limit will trip like i explained before. Are all your supply air and return air registers open and not restricted in any way? They all need to be open. Do you have central air conditioning? The cooling coil in the plenum above your furnace(if your furnace is in a basement) may be dirty. You will need an experienced service tech to check it and clean it if it needs to be cleaned. I have ran into many systems in my business where the furnace is oversized for the size of the house and the furnace will consistently cycle on and off on the hi-limit contol for years util the hi-limit gets weak and fails. If that is the case you need to get a smaller BTU furnace as that is the only cure. Sometimes the ductwork was installed to small and you can't get enough air flow(supply or return) if thats the case there's not alot that you can do if all the ductwork in buried in the walls and ceilings. You will still need to re-install the hi-limit with a new one. It hase to be the same temperature rating as the one you took out. Contact your local dealer for one.
On your question about the flame sensor, it is the small probe that is actually on the last burner(the last burner that gets gas and lights). It is held in place by a single screw and has 1 wire going to it. Hope I was of help to you!! Good luck!!

Nov 28, 2009 | Heating & Cooling

1 Answer

Weatherking WRKA heat not working control board

U need to supply more info.There will be a sticker on the furnace likely in the lower Fan Compartment which will have a legend that explains each error 3 blinks = Pressure switch etc....and u will need to provide more info on how the furnace is operating (whats it doing ) when it stops working or just prior to that

Oct 16, 2009 | Heating & Cooling

1 Answer

Igniter keeps breaking

Wow, this is a new one on me! Are you using true OEM parts for your source? If not, you may be getting sub standard parts. There are some companies that use generic parts and this isn't a good thing to do sometimes. Weatherking is a Rheem/Ruud product.

Apr 10, 2009 | Weather King 12AJA4801AH Air Conditioner

1 Answer

Weatherking Short Cycling

You make a good point about overheating on heat exchanger temp.

Since you don't have to reset anything for it to recycle, then I assume you have one of the newer forced draft furnaces.

There should be leds on the control board inside the furnace compartment that will blink a code to you, telling what the shutdown reason was. Blinks and code should be on a label inside the blower door panel, or inside the control box cover.

Let me know what they are, and I can give you more direction. I am assuming this furnace worked at some point, and no changes have been made (including closing of duct vents).

Jan 26, 2009 | Kitchen Appliances - Others

3 Answers

WeatherKing Acclaim II

  1. The sensor that tells the furnace whether the gas is lit has got build-up on it and is giving the furnace bad information.
  2. The flame sensor is often a single wire or rod that sticks up in the center of the flame.
  3. You can shut off the furnace and the gas and clean the sensor with some sandpaper.
If that still doesn't work, the sensor may need to be replaced.

Please rate this solution.

Jan 16, 2009 | Heating & Cooling

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