C340056P04 - Trane OEM Furnace 3" Replacement Limit Switch

I bought this Brand because it was fast delivery and matched the specifications of my original switch (my furnace is an Armstrong). The original switch is no longer available and the replacement is Armstrong 36W90 - A number of companies use the same switch. The screw holes are even the same. The quality of this replacement looked good and the furnace is now up and running. The photos show the new switch installed the other two photos show the older black switch (Armstrong) and this new Trane switch.

Easy to install & this will replace MANY made type Furnaces.You must match operation specs to your furnace !

Worked as intended. Happy customer

This is NOT a 190-30F thermal limit switch. It is NOT the same fit as the original Trane 190-30F part. It is NOT C340056P04 SWT01259.The delivered part I received says 190-40F, which technically is ok as the lower limit just increases the hysteresis cool down time before it kicks back on.However, the part doesn't fit exactly the same. The holes don't line up exactly...the base thickness is different and not quite big enough. The sensor probe length is not the exact same. The net result was that the sensor makes contact with metal flap in furnace after it is fastened. I ended up getting a short to ground (~2.3 Ohms). It almost blew out the control board. Fortunately, my fuse blew instead and saved the frying the electronics - but we were freezing cold for a couple nights until I could find a replacement blade fuse for control board..Once I put the original thermal limit switch, from the original manufacturer back in, the short circuit was gone. Now I still need to find the Trane 190F-30 switch. In the q/a, the seller indicated this was the 190-30F switch and this is listed as Trane part. It is NOT and it is NOT a direct fit.Please check the resistance to ground from the switch terminals after install. As the shape of this sensor is not an exact fit, it causes issues as there is a metal flap inside the furnace that I suspect it makes contact with, once the screws are fastened as it pulls the sensor probe closer to it. Unfortunately, I can't see inside that part after its installed.I have never posted a review previously. I am only doing so because I don't want anybody else to lose heat - or worse have their control board fried.

Offset slots for mounting were perfect. Spade connectors correct size. Seems to be working.

Service call to replace this item was going to me around $900.00. Took me about 30 min. - I am not a mechanic - just do one wire at a time. Furnace people are right - might be cheaper to get a new furnace than to let them fix the old one - but if you do it yourself - you can save the cost of a new furnace. Furnace is 17 years old - it works just fine & new replace parts are much better than the factory ones.Denny

This part fixed our furnace so we didn't freeze 🥶 -30° wind chill.

I am changing my review from one star to three stars just because I got it to work it's not shorting out anymore what was happening was the Leeds on the backside we're contacting the furnace housing because they weren't the exact same spot as the OEM replacement a little trim off the board and got it to work