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Webb-Guy
Webb-Guy, HVAC Mechanic
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Experience:  maitenance tech at casto
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I have a 3400-818 furnace and it doesn't come on. The fan

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I have a coleman 3400-818 furnace and it doesn't come on. The fan works with a override switch but the furnace will not come on with the thermostat?
JA: Just to clarify, do you think this is a larger HVAC problem, or something specific to the thermostat?
Customer: That is the question. If it is the thermostat, easy fix, buy another as this one is a 30 yr old emerson that I can't find trouble shooting techniques for?
JA: Do you plan on doing the work yourself?
Customer: Yes, I fixed aircraft radar in the navy and worked as a tech for IBM for 20 years and am now a part time handyman. Can you give me some hints?
JA: Anything else we should know to help you best?
Customer: Not that I can think of!

Hello, and welcome to JustAnswer. my name is ***** ***** I will be the one to assist you. If its working with the override switch but not with the thermostat then more then likely yes the problem is with the thermostat and its going to need to be replaced.

Customer: replied 1 month ago.
The override switch as you call it has no wires hooked to it underneath I'm talking about a switch on the wall that is been wired straight to the fan itself just for purposes of turn the fan on for the summertime. So to be clear the override switch is not in play on this furnace as there are no wires hook to the bottom of it it does nothing!

ok so that was my misunderstanding. Have you tried turning off the circuit for 5 minutes to the furnace?

Customer: replied 1 month ago.
I think it may be the sequencers for my Coleman 3400 - 818 but I haven't been able to find a part number for them can you help with that?

your sequencer part number is *****

Customer: replied 1 month ago.
The sequences are a guess on my part obviously but would love to know how to measure with a meter to find out for sure? Is that possible

you can measure it for continuity.

Please note that we here at JustAnswer are on an honor system. I am only credited for my time in the event you rate with 3-5 stars at the top. I do hope that I have earned a 5 star rating from you today. Rating does not stop you from getting back to me in the event you need me.

Customer: replied 1 month ago.
There are many wires hook to the sequencers can you tell me how to which ones to measure continuity on I have the talent to do that just don't know which ones to measure or is there a schematic that will show me that?
Customer: replied 1 month ago.
I have a schematic for a 3400 - 815 but I fear it might be different than my 3400 - 818

I do not have the schematics for this one but here is a helpful video

https://www.youtube.com/watch?v=Za3AyJeG9ow

you should disconnect the wires from the coil terminals and measure the resistance of the coil. This will normally be around 20 ohms. If the reading is zero or considerably higher than 20, you should continue with electric furnace sequencer replacement

no it shouldn't be any different for measuring this

Customer: replied 1 month ago.
I will check that and get right back to you.
When you say the coil terminals are you talking about the coil to the right of the sequencers or you talking about coils within the sequencers?

the coils within

let me know what you find

Customer: replied 1 month ago.
Okay I'm going to check now

sounds good I am here

Please note that we here at JustAnswer are on an honor system. I am only credited for my time in the event you rate with 3-5 stars at the top. I do hope that I have earned a 5 star rating from you today. Rating does not stop you from getting back to me in the event you need me.

Customer: replied 1 month ago.
Okay, small problem, the schematic I have shows h numbers and on my sequencer it shows em numbers so I'm not sure which is which.
Customer: replied 1 month ago.
I could take some pictures and let you see what I am seeing if that will work anyhow on this forum

you can send a picture on here

Customer: replied 1 month ago.
I'll try and figure out how to do that
Customer: replied 1 month ago.
Going to take pictures now

there should be a little paper clip you can hit and add the picture that way

Customer: replied 1 month ago.
Can't tell if I'm sending needs or not but I'm trying. Can I just attach already taken pictures in my gallery or do I have to take the pictures on the Fly?

they came through one moment please

the pictures are pretty blurry and hard to get an understanding of the problem. Are you having a problem getting to it to test it?

Customer: replied 1 month ago.
Not sure which of these tabs to measure from and to I assume I have to take the wires off of them to make sure I'm reading just across the coil correct?
Customer: replied 1 month ago.
Okay, I make sure to Christ the high and the low pins on each of you to see and I got three odd numbers like 0 or 1320 $300 so I'm going to assume that sequencers are bad and order the new one.
Can I get a hold of you later somehow let you know what happened or ask more questions? No worries I will give you a good rating

yes you are more then welcome to follow up with me on here even after rating. just bookmark the page and come back to me if and when you need me again. Thats not a problem.

Customer: replied 1 month ago.
Okay, I think I figured out how to book Market I will order the part get it put in and let you know what was your name?

my name is Travis

Webb-Guy and other HVAC Specialists are ready to help you
Customer: replied 1 month ago.
I will assume that if I come back to this page it will have your name on it is that correct? If not I'll just try to remember see you soon, goodnight, thank you

yes you just bookmark this thread and it will bring you right back to this conversation also if you put your email address in then the thread should be saved on there from our back and forth.

Customer: replied 1 month ago.
Thank you, ***** ***** I have it and I gave you a great rating you are very helpful thank you so much for being patient!
Customer: replied 24 days ago.
I am still waiting for the sequencers and will let you know if that fixes the problem. Sorry for the delay!
Dan
Customer: replied 11 days ago.
I put in the new sequencer it did not fix the problem. I'm at a loss as to what to do next if you could help I would really appreciate it. Thank you. Dan