Help out a newb DIYer with AC Contactor

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Old 07-05-10, 05:49 PM
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Help out a newb DIYer with AC Contactor

Hi everyone!

New to the forum, and as most newbies are, I'm in search of help. I'm a relatively new DIYer, and enjoying learning new things on a daily basis. The adventure this time is HVAC.

Bought my house 3 years ago, built around 1989. First year the AC worked great, then last year it wouldn't kick on. Still being shy, I called out the repairman, only to watch him replace a $15 capacitor and leave me a nice bill I can't complain however, because his knowledge was well worth the bill. This year, things ran well for a couple of months, then came home to find the house hot. As it had been a long day, and I had a cranky lady uncomfortable with the heat, I called the repairman again. He came out to the house, we checked the thermostat and everything was fine.. As we ventured outside, he went to the truck to get gauges, and I went to the end out the house to the unit. I immediately noticed that the compressor was running, but the fan motor was just buzzing. A sharp smack later, and it began turning. He came over, I told him what happened, and before even cracking the unit he said it was probably the contactor. Can't say I had heard of a contactor before that day, but now I understand it's just another term for a relay, so all is well. Anyway, while he was there he checked the freon, said it was great, and looked at the contactor. He was a super nice guy who stated that what he would have to charge me to replace it was pretty high, but I seemed handy (I was replacing steering knuckles and tie rod ends on a car when he pulled up) and he recommended that I do it myself. I said no problem, thanked him, and away he went. The house cooled down and the better half and I went to friends for dinner.
When we arrived home, house was hot again. Walked outside ready to administer my "smack of motivation", but the motor just barely moved in rebellion...several smacks later, I realized that the original diagnosis was probably only part of the problem..I pretty much know a shot electric motor when I see one....SOOOO..next day I pulled the relay and motor after making a VERY detailed diagram of where all the wires go, and went to the local electronic supply (Locke, if it makes any difference). I tossed my contactor on the counter and asked for a replacement...the guy certainly wasn't positive, but gave me his best guess..I then went to an electric motor co and dropped off mine for diagnosis..Next morning I got a phone call that my suspicions where true...Bearings were shot and the motor was toast. A phonecall to Grainger, and I had a new one en route.
They also told me that I needed a new capacitor, so I said fine.

Next day I picked up the motor, installed it, hooked up the new contactor, flipped the switch and...nada. Nothing worked at all. If I held in the contactor, the compressor would start up, but the fan never did. Decided what the heck..hooked up the old contactor, and the compressor fired right up, but still no fan. The capacitor that was in the unit was a dual?, meaning it is cylinder shaped and has 3 sets of contacts..one from the hotside of the contactor, one that is the brown wire that goes to the fan motor, and the third that goes to the compressor. I thought that perhaps the cap they gave me maybe the key, even though it was a single...so I hooked it up this way...red wire from hot side of contactor to the new cap, then a brown wire out of the cap on the other set of contacts going to the motor. I then hooked up another red wire from the "in" side of the new cap to the "in" of the old cap. Make sense? Anyway, tried it this way, same result. Compressor kicked on, but no fan. Stuck a screwdriver in and gave it a push. Shazamm!!! Fan started turning and the house started cooling. This really got me curious, so I completely unhooked the new cap, hooked everything up as it was originally, and gave the blade a push again..Once more it started right up and the house was cooling. I let it run for awhile, then turned the stat up. The inside unit shut off, but the outside just kept on running. After a little investigation, I have found that the old contactor is sticking closed and not shutting off.

Which brings me to where I am now, and where I appeal to your knowledge to enlighten this schmuck!

1. OLD Contactor: Furnas 45DC10AJLL270
VAC 240
FLA 25
LRA 100
Non-Inf 30

2. NEW Contactor (not currently installed) GE CR453CC2BAA
VAC 240/277
FLA 30
LRA 180
RES 40

Soooo...about the only thing that i understand out of that is that they are both 240 volt units. If anyone cares to shed light on the rest of that, I love to learn!

So...my first question is this, what IS a proper replacement for my antique Furnas model?

2. The motors are identical spec wise, except the new one wants a 5 Mfarad cap (the new one they gave me) did I have it hooked up properly when I had both caps in the system?

3. Is the reason the motor won't start because of the contactor, the way I have the cap hooked up, a combination of both, or none of the above?

Anyway, I am all ears, and I really look forward to hearing from you all. I know I can always call the repairman again, but I feel like I am ----> <------- this close and would rather finally be able to depend on myself. Thanks!
-Adam
 
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Old 07-06-10, 12:56 PM
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old contactor should have a coil voltage of 24, but u do not have this info listed. new contactor should have coil voltage of 24, only thing u need info wise is: number of poles(2), vac(240) coil voltage(24). fla, lra, are just amps and anything over 20 will work and forget that other stuff.

the capacitor just starts the motor. the reason u have to push it to start if cuz u have the capacitor hooked up wrong. the new condenser fan motor should have 4 wires coming off of it. if it doesnt....get one that does. there will be 2 brown wires, one with a white stripe usually. hook both of these wires to the 5 mfd capacitor, one on one side and one on the other. then the other two remaining wires will go to left and right sides of the contactor.

and u in case u need to know... the red wire goes from the contactor to common on the dual capacitor. and the compressor wire goes to herm, if ur new dual capacitor(not the 5mfd) has a space labeled fan, u dont need anything hooked up to it. i guess they found that the fan motors last longer when they have their own separate 5 mfd cap instead of hooking it up to the dual capacitor. message me if u need help
 
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Old 07-06-10, 01:31 PM
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Originally Posted by ender2272 View Post
old contactor should have a coil voltage of 24, but u do not have this info listed. new contactor should have coil voltage of 24, only thing u need info wise is: number of poles(2), vac(240) coil voltage(24). fla, lra, are just amps and anything over 20 will work and forget that other stuff.
On the side of the coil on the old contactor it says "60 Hz 24V and 50Hz 24V"
New one has "208-240V 50Hz, 208-240V 60Hz"
Is this what you are referring to?


the capacitor just starts the motor. the reason u have to push it to start if cuz u have the capacitor hooked up wrong.
I don't have to push the capacitor to start anything. I'm pushing the contactor but only when I have the new one hooked up.

the new condenser fan motor should have 4 wires coming off of it. if it doesnt....get one that does. there will be 2 brown wires, one with a white stripe usually. hook both of these wires to the 5 mfd capacitor, one on one side and one on the other. then the other two remaining wires will go to left and right sides of the contactor.
Ok...this is where I'm getting totally lost. If the old fan motor only has 3 wires, why do I need a new one that has 4?

and u in case u need to know... the red wire goes from the contactor to common on the dual capacitor. and the compressor wire goes to herm, if ur new dual capacitor(not the 5mfd) has a space labeled fan, u dont need anything hooked up to it. i guess they found that the fan motors last longer when they have their own separate 5 mfd cap instead of hooking it up to the dual capacitor. message me if u need help
Where is the new cap hooked up? Am I missing that information in your post? Thanks for your help
 
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Old 07-06-10, 10:18 PM
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Furthermore, how do I actually know if the two contactors are compatible? Thanks for any input!
 
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Old 07-11-10, 12:39 AM
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Update!

So...after a little more research, I realized that I did, indeed, have the incorrect contact. Took it back and swapped it out, hooked it up..Fired it up, the COMPRESSOR TURNED ON and.....the fan would only start with a push

Did I get a bum motor or capacitor, or both?
 
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Old 07-11-10, 08:48 AM
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Originally Posted by Y2k7JK View Post
the COMPRESSOR TURNED ON and.....the fan would only start with a push
The fan capacitor is either hooked up wrong or it is shot. There doesn't seem to be anything wrong with the replacement fan motor. And, I'm skeptical that there was anything wrong with the original motor.
 
 

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