Hi, I have a Goodman gas pack about 15 years old. Wasn't lighting so I opened the cover and saw the limit switch was open. Pushed it, ran for 20 minutes, cut off. Tried again, same results. Put the closed switch on a mmeter and it read 76. Replace the switch, right?
Looking for the part, it has 240 F on mine, and the Goodman oem part number matching my switch has 250F. Can also get a 220F and a 300F. I'm assuming this is the temp when the switch pops open.
Which one to use? Many thanks

 

It read 76 ohms?
What was the supply air temperature when it tripped?

 

The only push-to-reset thermal sensors I know of are flame rollout switches.
Do you have flame coming out of the burner area ?

 

yes it did read 76 ohms. It was pushing nice warm air out.
It's mounted near the flues, but I don't see any flames where they aren't supposed to be.
I'm calling it a limit switch because that's what the supply houses call it, and they also call it a rollout.

 

Yes.... rollout..... flame rollout. When the flame is outside the burner area it's called rollout. It is a major problem. It can indicate a burner overfiring or a partially clogged flue line.

I would use a 3L12-250.......3L12-250 rollout switch
If you want to stay with the original temperature.... 3L12-240..... 3L-240 rollout switch

 

Is the flame actually rolling out and/or overheating the burner area?
Id check the heat exchanger. Is this a package unit?

 

this is the one I was looking at, with the same oem number

https://www.amazon.com/101235-30-Goo.../dp/B00FFG241W

but it says its 250.

it looks like the one you linked is the same size and the right temp

I'm assuming it's bad because when it's closed it's supposed to read zero, right?

Thanks!

 

Yes.... when the button is pressed.... it should show show near 0 ohms.
That part you linked to is also ok.
It could have just gone bad. You'll know after you replace it because if it trips again.... you've got problems.

 

yep, I appreciate it, thx!

 

hey roughneck, yes, its a/c and gas furnace goodman gpc10300701a, installed in 2005

before I order a new switch I'll fire it up and pay closer attention to the flames and where they're at since y'all have brought that up. My new mental picture of rollout makes me think it's going to be obvious...... Thx

 

First, thanks for sharing your expertise with folks like me who wish to learn. I was re-reading my post, because the issue is back now that the weather is cold. I had called the pro who installed the unit when I was having issues last year, and I'm not sure what he did, but the issue is back. So I took off my covers, and the LED is blinking with one blink, which my owners manual says is a lockout due to failed ignition or flame dropouts. So I turned the thermostat off, heard it click, went back outside, the LED is solid. It's about 58 outside today. My indoor temp on the thermostat is 69, I have a gas log that's warming up the inside of the house, so I set the heat to 72, cut it on, went outside, the blower fan came on, the ignite came on, the burners lit and all seemed fine. Ran about 3 minutes and the blue flames disappeared. It didn't raise the house temp any. Soon after, it tried to light again, but there was obviously no gas, it tried twice, I could see the igniter post sparking. The LED reads one blink. Here's the thing. I think the pro put a different switch where the rollout switch is because this one does not have a reset button on it, and the old one definitely did. So that's concerning. I took it off to look at it closer and when I shake it, it rattles. The pro is knee deep in calls and can't come until Thursday, but I ain't sure I'm sticking with him anyway. I saw one post where the rubber tube that's connected to the pressure switch was giving another reader an issue. If anyone can offer advice here, many thanks!

 

I think removing the switch reset it, because the same scenario happened when I fired it up again, but this time, after cutting off, the igniter came on and the gas came on and the furnace lit. It did it twice, and then locked out.
Thanks