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We were corresponding last year, but I dropped the ball and…

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Hi, we were corresponding last...
Hi, we were corresponding last year, but I dropped the ball and never followed up. Can you re-read our conversation and pickup where we left off?
Submitted: 5 months ago.Category: HVAC
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Customer reply replied 5 months ago
I have a Coleman Furnace TM9X080B12MP11A. It does not satisfy the thermostat temp in the mornings. I setback the temp to 64 at night. Cal for heat in the morning for 70. The furnace turns off at 66 or 67 degrees. The thermostat still shows that it is heating, but the furnace is off. I have turn themode to off, then back on in order for the furnace to resume and satisfy the thermostat temp. There is a horizontal furnace in a crawl space with 2" pvc up through the roof chimney. Condensate T goes to 1/2" clear rubber tube to condensate pump. Tube has been cleaned. Filters are clean.There are 4 blinking red lights. Can you help me check the limits to see if one of them is open?
Answered in 6 hours by:
12/16/2017
HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
D.E. Anderson
D.E. Anderson, Industrial Refrigeration Service Manager
Category: HVAC
Satisfied Customers: 200
Experience: 15 years experience. Design, install, service of residential & commercial hvac/r equip.
Verified
Sure. I apologize for the delay. I am eating dinner at the moment with some family visiting. Give me a little while to wrap this up and look up your furnace and I'll be back in touch. Thank you for your understanding
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Customer reply replied 5 months ago
No problem. Enjoy the meal and family. I look forward to hearing from you.Mike
HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
Is it possible for you to post a link to the previous question so I can get some background from last year? Thanks.
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Customer reply replied 5 months ago
https://my-secure.justanswer.com/question/index/2138a8423aed4666b264da95ec4b9c72?continueTheConversation=False&comingFromAdservEmail=False&ratedThroughEmail=False&rating=0&paymentType=UnknownYes see if this works:
HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
Is the furnace currently locked out?
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Customer reply replied 5 months ago
No it still works
HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
The limit the code indicates is opening is located inside the burner compartment on the wall just beyond the gas valve. Do you have a volt meter available?
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Customer reply replied 5 months ago
I do have a multi meter.
HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
The code indicates that the main limit is open. If you observe the furnace operation, when the furnace shuts off prematurely, you can disconnect power from the furnace. Remove the door panel at the burner compartment, look for that limit at the back. Remove the wires running to it and if your meter has an ohm setting, it'll be the symbol that resembles a horseshoe, set it to there on the lowest range and ohm that limit and verify it's open. Let me know when you do and then we can go from there. Have you verified the evaporator coil for your air conditioner is clean? Thanks
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Customer reply replied 5 months ago
Ok. A couple of questions- 1) So once the furnace turns off prematurely, I should disconnect power from the furnace- how do I do that, by turning off the wall switch? 2) what does a “limit” look like? What should I be looking for? So pull off both wires and put each end of the multi meter in it’s place?I haven’t verified the evaporator coil..
HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
disconnect power from the nearby switch or breaker, verify the power is off. The limits are usually rectangular with two male connectors on them with a wire run to each. Give me a moment and I'll find a picture to send you
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Customer reply replied 5 months ago
Ok got it. I have to sleep now but will circle back with you tomorrow once I check the limit. Thanks!
HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
OK, sounds good. Also check the cleanliness of the evaporator if you can. Have a good night
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Customer reply replied 5 months ago
Good morning. I check the limit. It reads 0. But I should tell you that when I open the panel doors, the 4 lights stopped blinking. There is a door switch that when opened, I believe it powers everything off
HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
If you didn't observe it cutoff and it's been off awhile then the limit would show closed with no resistance. I knew there's a door switch. That's typical. I would watch the furnace while it's running and wait till I witnessed it shutdown. Then check the limit
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Customer reply replied 5 months ago
Ok.. it's a horizontal setup in a crawlspace so it's hard to get in there right away. It's been about 10 minutes.. should I try now or reset and wait until it goes off again?
HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
Sorry for the delay. I would try to be observant of when it cuts off again. When the main limit trips the blower will continue to run and is indicative of the limit being open so you can't rely on the blower shutting off to recognize when it shuts off the burners. I suspect if you watch it while it's running you'll see the burners shutdown within 15min
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Customer reply replied 5 months ago
Ahh ok. I did just measure again and it’s still 0.0, but that was within a minute or so after the blower turned off. I’ll get in there again and keep an eye for when the burner shuts down and get back to you
Customer reply replied 5 months ago
Ok I measured again, this time within 30 seconds of the burner cutting off (blower kept going like you said.) I powered off the furnace, took of door panel and measured the limit. My multi meter says 0.LIt also says 0.L before I measureI did notice what looks to be two other limits, and they measure 0.0.
Customer reply replied 5 months ago
I got a message that you responded, but I don't see it here - can you reply again?
HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
0 would imply no resistance. I think either there is a problem with your meter or your probe. At any rate I think based upon the operation of the furnace we can conclude the limit is in fact opening. How does the flame pattern look at the burners when it runs? Is this LP or natural gas? Did you check the cleanliness of the evaporator coil? Thanks
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Customer reply replied 5 months ago
I checked the multi meter directions. O.L means open loop. It’s natural gas.. I didn’t look at the flame pattern and I don’t know how to check the Evap coil yet.. but I will work on those items. it’s never been cleaned and it’s about 6 years old.
HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
I thought you meant zero. Yes OL would indicate the control is open. If it's never been cleaned it may need it. You can remove the door panels over the evaporator and inspect it. Any restriction in air flow will clear an over heat situation that will cause the limit to open. I want to check all the simple causes before we start digging too deep. Thanks.
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HVAC Technician: D.E. Anderson, Industrial Refrigeration Service Manager replied 5 months ago
create an overheat situation is what I intended to say
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Customer reply replied 5 months ago
ok got it. I’ll get in there and check the coil soon. Thanks!
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