Thread Number: 40167  /  Tag: Other Home Products or Autos
I fixed my central A/C!
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Post# 426507   6/5/2020 at 09:57 (229 days old) by human (Pines of Carolina)        

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I'm feeling very empowered right now. I have an ongoing problem with burnt wires on my central air conditioning system. Not surprisingly, it usually happens when temperatures are in the 90s and the system is running almost non-stop. In the past, when I had a home warranty, I'd call in a claim, wait almost a week for a technician to come out and fix it in about 15 minutes, then pony up the $100 service fee. The first few years I lived in this house, this would happen at least a couple of times a summer and seemingly always on or just before a weekend where I'd have to wait several extra days for a technician. Two years ago, I decided to get off that merry-go-round and let my home warranty go. So far, that has worked very much to my financial advantage. I also haven't had any trouble with burnt wires for a couple of years since the last technician who came out had the bright idea of upgrading all the wires to a heavier gauge.

But yesterday, the inevitable happened when temperatures reached the mid-90s for the first time this season. Once I realized what had happened, I found the burnt wire in about two seconds and decided to take matters into my own hands. I mean, it's just a wire; it's not brain surgery, so after breakfast this morning, I went to Lowe's, bought a pack of wire connectors, cut an inch or so off the wire to remove the burnt section, then removed the remains of the burnt connector from the relay it was on, replaced it and voila! The air conditioner (a 50-year-old Singer unit that's original to my 1970 house) was back in business—and with no $100 service fee and no waiting, except to wait for Lowe's to open this morning as I discovered the problem last night, well after our city's present 8:00 p.m. curfew.

Post# 426508 , Reply# 1   6/5/2020 at 12:22 (229 days old) by gregvacs28 (space coast)        

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ummm, I hope you realize that burned wires is not normal.   


Good for you for fixing this problem yourself, but.....


Do you have a window AC as a back up for when this baby finally catches fire?  .....and a fire extinguisher.  


I wouldn't leave the house with that thing running.  You want to be there when things go down.  


Window A/Cs or mini splits are much more efficient that central air, jfyi.  




Post# 426515 , Reply# 2   6/5/2020 at 14:22 (228 days old) by human (Pines of Carolina)        
Same repair as at least half a dozen or so HVAC techs made

human's profile picture
This all started in the summer of 2014 when the blower motor in the gas furnace, which also serves as the air handler for the air conditioner, burned up. After the motor was replaced, the burnt wires started happening with the aforementioned regularity. My former home warranty company would dispatch a random service company from their list and some inspired more confidence than others. It was rare the same company or the same technician would come out twice. Each time, I would give the technician a history of the problem and each time, they did nothing more than treat the symptom by replacing the burnt wires. Never did any of them dig any deeper into the problem than that.

I have a suspicion (unconfirmed, of course) that the home warranty company may have only authorized a minimal repair to get the system working again, rather than taking a more thorough approach. One technician told me that given the age of the system, the home warranty wouldn't cover a replacement, only incremental repairs. That said, I do believe the technician who took the extra step of upgrading the wiring was on the right track, as borne out by the lack of any recurrence of the issue for two years.

The orange wire (lower left) in the photo below is the one I repaired. It overheated at the point where it connected to the little box, which I assume is a relay to control the blower. The relay itself doesn't appear to have been damaged although the plastic insulator on the connector was completely melted and the last inch of the wire was discolored and fell from the connector when I touched it. The technician who replaced the blower installed that relay and left it hanging like that. Subsequent technicians have not been inclined to secure it. I am not certain whether the same wire overheated each time and I don't believe the last technician replaced those wires as the ones he put on the blower itself were all yellow.

I do have a small window A/C unit that I bought a few years ago to stick in my bedroom window while waiting six days for a repair technician. The configuration of my vinyl replacement windows isn't conducive to leaving it permanently installed, especially since the flex mount is too narrow to span the width of the window opening. Filling the gap with cardboard and tape is acceptable only as a temporary solution. And yeah, I have fire extinguishers.

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Post# 426531 , Reply# 3   6/5/2020 at 20:29 (228 days old) by gregvacs28 (space coast)        

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It looks like you have the right idea.  


What did you crimp that with?  There is a special tool for crimping.  

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Post# 426533 , Reply# 4   6/5/2020 at 20:34 (228 days old) by gregvacs28 (space coast)        

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I don't know your house size, needs, etc.  


You can get mini-split systems on ebay.  Depending on how handy you are you may be able to install yourself.  


I've tried these mini splits a couple of times and they are really efficient and quiet.

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Post# 426534 , Reply# 5   6/5/2020 at 21:21 (228 days old) by MadMan (Chicago, IL, USA)        

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2nd on investing in a proper crimping tool. I hate those ones that just squish it into an oval shape, those connections never seem to hold.

I'm wondering if that wire you fixed was inside the furnace / air handler or outside in the condenser unit. You really should investigate this further, I'd be happy to help you along. That little box looks like a 120v-coil relay. Though it could be any kind of relay or even a motor start switch. I wonder what it controls that is drawing so much juice?

Investing in a completely new A/C system is most likely not necessary. This is probably some trivial matter. Those wires may still not be big enough, or perhaps it's powering something that has an issue. Might want to replace the capacitors in your condenser unit just for maintenance's sake.

Post# 426556 , Reply# 6   6/6/2020 at 10:35 (228 days old) by fan-of-fans (USA)        

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Could you post pictures of the system? It would be cool to see a 1970 system, not many that old here in FL. Does it use the round ceiling mounted diffusers? Most here in the 1950s up until about 1972 had a round vent or two in each room near the center of the ceiling, then they went to rectangular ceiling vents near the wall.

Post# 426557 , Reply# 7   6/6/2020 at 11:22 (228 days old) by human (Pines of Carolina)        

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I used vice grips to crimp that wire. It was what I had on hand. Maybe next time I'll invest in a pair of crimpers.

That relay is inside the furnace closet. It appears to be connected to a larger junction box with another relay, situated between the furnace and the thermostat, so it could well be a motor start switch. The relay was actually a little warm when I fixed the wire. The furnace is actually a 120v unit instead of 220v. This made it difficult to source a blower motor when it went out. The capacitors were replaced in 2014 when the condenser outside received a heavy servicing, including a new blower motor.

The house is a 1,300 square foot ranch and the system is more than adequate for heating and cooling the space. Usage reports from the power company routinely show my house to be among the most efficient in the area for its size and age. The vents are rectangular, mounted at the tops of the walls. The ceiling in the hallway is lower than in the rooms to accommodate the ductwork. Replacing the entire system is an absolutely last resort. I've had more than one HVAC technician tell me to keep what I've got as long as I can because nothing on the market will be anywhere near as durable.

Post# 426601 , Reply# 8   6/7/2020 at 02:16 (227 days old) by MadMan (Chicago, IL, USA)        

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Furnaces are usually 120v, A/C's are 240v. You mean your A/C is 120v? O_o

Relays will get warm in use, that's normal. Good on you for improvising a crimping tool.

Post# 426606 , Reply# 9   6/7/2020 at 09:52 (227 days old) by human (Pines of Carolina)        

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Yes, the furnace is 120v and the A/C is 220v.

Post# 426626 , Reply# 10   6/7/2020 at 17:07 (226 days old) by MadMan (Chicago, IL, USA)        

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Oh ok, that's normal to me then. Maybe it's a local thing? Anyhow you should probably still track down the root cause of that problem.

Post# 426638 , Reply# 11   6/7/2020 at 18:57 (226 days old) by Lesinutah (Utah)        
Its funny

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The air conditioner could be repaired by a plumber or an electrician. Yet the cheapest of the three trades HVAC are the ones doing the repair.
If we're going to get correct you should solder the wires back together and heat shrink to seal it. Then you wouldn't have to worry about using the right crimpers.
The crimpers I think might be $2 at harbor freight.
There is wire connectors with solder inside and heat shrink on the outside. You connect the wires and use a heat gun and it solders wires together and seals heat shrink.
I'm told there at auto parts store.
I personally think it's perfectly fine what you did.

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Post# 426668 , Reply# 12   6/8/2020 at 08:31 (226 days old) by vacuumlad1650 (Coal City, IL)        

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I use those Solder filled crimp connectors in my automotive them! No more worries about a bad crimp job, and no more cutting heat shrink!

Post# 426673 , Reply# 13   6/8/2020 at 13:54 (226 days old) by Lesinutah (Utah)        

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I've heard people who used them. The one he used a lighter on them.

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