burnt wire odor

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Old 12-15-14, 01:23 PM
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burnt wire odor

Yesterday evening just before time to go to church we noticed a burnt wire smell in the kitchen and my office off of the kitchen. I was able to isolate the odor at the HVAC vents. These vents are the furthest from the air handler, the odor was a lot less at the vents closer to the air handler

I thought maybe it was the blower motor so I turned off the heat pump and we went to church. When we came back I turned the HP back on but the blower didn't seem like it was turning and the burnt wire odor came back so I shut it down and built a fire.

Today a went in the crawlspace, took the cover off the air handler and turned it on. The blower works great and there is no burnt wire odor anywhere. I ran the HP for about 15 minutes and left the blower on for an hour after I turned the thermostat down. There isn't even a whiff of burnt wire odor. I'm totally confused! any ideas as to what was going on?
 
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Old 12-15-14, 02:12 PM
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Aside from the devil trying to keep you from going to church....not a clue.
 
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Old 12-15-14, 03:22 PM
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That is pretty strange. It's common to smell a burning blower motor but usually that smell is present at all registers and especially at the air handler.
 
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Old 12-15-14, 06:16 PM
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How old is the system? What is the air handler model and serial number? Possible weak capacitor caused the fan motor to overheat or faulty fan relay kept the motor from turning on. I have found melted wires at the main panel due to loose connections. If your not comfortable with high voltage call a pro.
 
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Old 12-15-14, 07:05 PM
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A weak capacitor is the first thing cause that comes to my mind with these symptoms but ksefan has listed some other common causes for a burned smell.

It is easy to check a capacitor with a meter that measures capacitance.
 

Last edited by Houston204; 12-15-14 at 09:05 PM.
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Old 12-16-14, 02:49 AM
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How old is the system? What is the air handler model and serial number?
It's an 18 yr old Janitrol, A32-15 although I replaced the motor and capacitor several yrs ago [maybe 5] I didn't see any melted wires but some of the connections are corroded. My wife has a doctor appointment this morning and then she wants to go Christmas shopping so I doubt I'll be able to crawl back under the house to check it out today

Can the capacitor be checked with an analog meter? I also have a cheap digital meter but I've never been very good with it.
 
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Old 12-16-14, 04:12 AM
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Have you noticed anymore burning smell? Most cheap meters do not measure capacitance. Capacitors are cheap, might be best to replace it. Test the return air and supply air at the closest register to determine ballpark airflow. Sounds like a possible loose wire, if not the main panel check the heat element and relay connections for discoloration from overheating.
 
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Old 12-16-14, 11:47 AM
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The corroded connections weren't as bad as I thought. They were just on the breaker plug in connectors and only on the outside. I went ahead and cleaned them, I also removed the capacitor and will get a new one when I go back to town. I've not seen any sign of melted or discolored wires. The heat strip is disconnected [my wife likes to fiddle with the thermostat ]
 
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Old 12-16-14, 01:44 PM
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Janitrol/Goodman are notorious for fan relay problems. 90/370 relay.
 
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Old 12-16-14, 09:14 PM
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This UNI-T UT210E is the best cheap meter that I have used so far but I only received it yesterday. It fits in my shirt pocket much better than my Fluke 902 or Klein CL2300.

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It ran 1/10th the price that I paid for my Fluke 902.
I has a much better Ohm range than my Fluke and can measure up to 2000 microfarad.

The UT210D also has temperature but Amazon doesn't carry it yet.
 
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Old 12-17-14, 12:17 PM
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I'm about to give up The blower/fan is fine. It runs without any odor! When the HP kicks in the odor returns. It has a stronger smell the farther you get from the air handler At the air handler there is a faint odor in the compartment that houses all the wires and connectors. I flipped the breaker on for the heat strip and the odor increased so I don't believe they have been on. There are no burnt or discolored wires in the air handler.

The only thing left I know to do is just ignore the odor and see if it goes away. If it doesn't, I assume whatever is wrong will fail and maybe then I can find/fix it.
 
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Old 12-17-14, 03:13 PM
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I know yours is a heat pump, but don't let it get like the estimate I went on today. Gas furnace, newer house, probably less than 8 years old. Something went wrong in the furnace and all the ducts became flame throwers, melting the flex and scorching insulation, plumbing, wiring, everything. Luckily it didn't burn down. We can't even get in the house until after the new year due to other trades having to replace so much. Be careful, my friend.
 
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Old 12-17-14, 04:43 PM
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I agree, ignoring a potential fire hazard may be a mistake.

I have seen electric heat strips create a light show in an air handler before. I have also seen a poor wire nut connection melt and take out the reversing valve coil, defrost timer, thermostat, and the circuit board in an air handler.

If you cannot find the cause it may be time to call in a pro.
 
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Old 12-18-14, 03:32 AM
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Could it be the blower motor?? Woke up this morning and heard the heat pump running and the bedroom was warm but when we walked down the hallway we could smell the odor. I also noticed that the air handler fan was not running. I shut down the HP and built a fire then tried to turn just the fan on but it wouldn't come on. I suspect later today that it will run and work fine with no odor for an hour or two and then repeat the issue.

The heat strips are turned off [have been for 15+ yrs] so they shouldn't be an issue .... and I can't find any melted or discolored wires anywhere in the air handler.
 
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Old 12-18-14, 07:18 AM
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more confused after being shut off for awhile I turned the HP back on and it worked fine although I had to shut the heat down after a little bit [fire in wood stove] but I left the fan on and after 2 hrs the blower is still working and no burnt wire odor.
 
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Old 12-18-14, 08:08 AM
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Possible intermittant fan relay problems are common om janitrols, probably best to call a pro. If you do let us know what they find.
 
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Old 12-18-14, 08:56 AM
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The fan has run for the last 4 hrs with no issues. Money is a little tight right now so I'll probably hold off until next year to call in a pro .... but at least I have a wood stove Personally I prefer wood heat but my wife likes the heat pump better.
 
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