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jb64 05-07-2012 02:40 PM

Wires on Fire
 
AC condensor unit started with a reversed bent blade cooling fan. Vibrations loosened power cable, wires grounded and burned up:furious: Replaced wire harness, wires burned up:furious: Wires also transferred heat to the local breaker, it burned up:furious: Changed all components, in this case, start relay(carbonized contacts), all caps including "hard start" and "bonus" cap for the fan not in the schematic. System failed, breaker inside overheated and burned open:furious: Replaced it. Cooling fan got tight, system failed. And for those who helped brilliantly with the 4m205j thread, I swapped parts out of that unit to troubleshoot this one. So..
1. The fan motor that failed had bushing not bearing, lubricated with "oily sawdust" should I just change it?
2. Reversed cooling fan, any more expected problems?
3. Hard start caps, are they ok or a "band-aid"?
4. My breakers are rated for ambient 40C, 104F, in Houston area this is a cool summer day:laughing:, is it normal to use these?
5. I have slim line GE breakers inside panel, it seems if changed to the wider body breaker it should be able to dissapate more heat?

Doc Holliday 05-07-2012 03:12 PM

Are you being sarcastic with your use of the term "brilliantly helped"? I can't tell nor could I tell last time with your last post what it is you're wanting. If you need(ed) help with wiring than ask in a manner we can all understand. Pics always help as well.

And I just can't help but say that this is a perfect example of why certain things are best left to the professional AND I can't help but say I told you so for running the system without refrigerant. I'd be willing to bet you're compressor is fried as well. Something was terribley wrong with the wiring for this to occur, phase to phase or something.

I don't kow what to tell you any longer, obvously you jumped the gun. Next time it may be your entire home that burns. Might be time to call out that professional I was talking about.

Doc Holliday 05-07-2012 03:49 PM

Btw, there is not such a thing as a "bonus" cap for the fan. Compressor's have hard start kits to assist in their starting as they have refrigerant equaliziation issues to overcome. There is no air equalization issues that a fan motor needs to fight. If there were a "bonus" fan cap I'd have heard of it by now in my 12 years in this trade. Someone can correct me if I'm wrong.


Hard start kits can amplify electrical current by up to 600% for the compressor alone. Your normal caps only do it to about 3 times the normal voltage.


I don't know what you did but you royally screwed up. Do you have any idea how hot a normally well lubed compressor becomes on start up? What happens to a car without any oil in it? The motor seizes and many catch on fire in the process.



You had mutliple concerns that needed to be addressed and you ignored them and now you're paying the hefty price. I certainly hope you don't go about attempting to run new circuits/wiring or messing with the elecrical service panel where the breakers are. I'd also be willing to bet your wiring to the unit is fried, got way too hot. All wiring is only rated to a certain temperature and once that temp is reached or breached the wire and the insulation are never the same, not trustworthy. It could start a fire even once everything is wired in properly.and assumed running well.


This work is far outside of your realm of comprehension. Be smart, be safe, call the pro's.


Good luck.

jb64 05-07-2012 03:50 PM

Doc,
Please slow down. NO sarcasism. Looking for friends, not enemies. The second unit has been running ok mid last since summer. I was trying to be humorus on this post. Maybe, I am the local professional.

Doc Holliday 05-07-2012 03:56 PM

If all professionals were of your caliber than us tradesmen would be better off joing the fire department.

jb64 05-07-2012 04:11 PM

Doc Please,

Slow down, jb 64 is my birth year. In '85 I worked on motor control centers and fire pump controlers in and around Chicago. 480v standing in water, electrical explosions, common, worked on 5100 volt controls. I never asked what current should it draw, no questions about wire size, just looking for local residential experienced person.

Ravenworks 05-07-2012 04:58 PM

My concern is you using those slim breakers,are you sure that you are drawing off of post phases?

beenthere 05-07-2012 05:03 PM

1. The fan motor that failed had bushing not bearing, lubricated with "oily sawdust" should I just change it? Flip of the quarter


2. Reversed cooling fan, any more expected problems? Not really.


3. Hard start caps, are they ok or a "band-aid"? helps the compressor get off its locked rotor quicker, which saves the start windings.


4. My breakers are rated for ambient 40C, 104F, in Houston area this is a cool summer day:laughing:, is it normal to use these? Your breakers are inside your home, the area the breaker is in is not at or above 40C. So they are fine to use.


5. I have slim line GE breakers inside panel, it seems if changed to the wider body breaker it should be able to dissapate more heat? See answer to 4.

jb64 05-07-2012 05:07 PM

Doc,
Maybe I confused you, sorry. I have two 5 ton ac units and one 3 ton ac unit. 1 of the 5 ton has no freon, its off. The other was the original problem with the wires and extra caps. I have that one (wire fire) running since last summer(hot). I measure the current of all routinely, all ok, even when the one with burned wires was in spec.

jb64 05-07-2012 05:10 PM

Beenthere,
Thanks for not joining the fire dept:jester:

jb64 05-07-2012 05:12 PM

Bt,
Breaker boxes for each unit out by the condensers, inside breaker boxes in garage.

beenthere 05-07-2012 05:13 PM

What size are the breakers, and what size is the max breaker size the condensers list.

jb64 05-07-2012 05:17 PM

BT & Doc,
I mean it, you both really helped with the other unit, its ready for freon. I was having brain problems believing 2.5 mfd difference was going to double the run current, I was way wrong.

beenthere 05-07-2012 05:23 PM

Run capacitors aren't actually used to provide more power to motors. Rather they throw off the sine wave. A small change in uf, can make a big difference in amp draw.

jb64 05-07-2012 05:25 PM

BT,
Size, amps 60 wide body sq D outside, GE 50 slim in box in garage, all dimensions similar except width, large 1.5", thin 1"


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