Central Air Unit won't run connector pops up?


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Old 05-15-13, 05:23 PM
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Central Air Unit won't run connector pops up?

I pulled off the top of the Central AC unit and found a connector that has springs on it that will not stay down. If I hold them down the unit runs, but it goes off when I let it go. I have a picture

It is like the top of this connector is missing which would hold the springs down.

Recognize this connector? The brown plastic has springs under it that will not stay down?



http://************/r/2z80sk0/5



http://i40.************/2z80sk0.jpg
 

Last edited by Deekus; 05-15-13 at 05:30 PM. Reason: can not ad picture
  #2  
Old 05-15-13, 05:51 PM
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Can not see your picture, but from what just said, that is the 'contactor' which is powered by 24V electricity, you should find 2 small wires come to your outside unit, those 2 wires should carry 24v when you turn your AC on and the button should be pulled down to start the unit. it suppose to pops up when the 24 V is cut by your T-stat to stop the unit. You need to check the T-stat and the transformer which provides the 24V to the contactor.
 
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Old 05-15-13, 05:53 PM
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Boy, talk about impossible to post a picture... going to try another forum.
 
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Old 05-15-13, 05:57 PM
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Thanks Clocert,
Makes sense to me... but I wonder how it worked last season? It looks like some wires have been cut coming from the basement to the unit. I didn't notice a transformer. Would that be in the basement?
 
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Old 05-15-13, 06:00 PM
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We don't need to see the picture, the contactor problem is very common, either you lost 24V on that small wire or the contactor itself is bad. So, turn the AC on, check small wires for 24V, if 24V is there, replace contactor, if not, check transformer and T-stat. (the transformer is in your air handler somewhere near or right next to the fan blower)
 
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Old 05-15-13, 06:11 PM
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Posting images.

You can not link to images that do not reveal the actual url of the image host like tinyurl or similar.

There is too big a risk in clicking a link that does not reveal its true location.
 
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Old 05-15-13, 06:58 PM
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It's possible a safety, such as a low pressure switch, has the contactor locked out.
 
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Old 05-15-13, 07:07 PM
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So how do I post a picture then?
 
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Old 05-15-13, 07:12 PM
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I think you have it nailed Clocert, but what is so weird is the AC guys fixed this unit last season and it ran fine and I don't think they even had 24 volts connected. It is weird all wires that would connect the 24 volts are disconnected, yet this thing ran last summer. Any idea how that could happen? As far as I know no one took the top off and disconneted stuff.

Could they have skipped over the 24 volt relay some how?

Also I don't know what a T-stat is?

oops okay now I get it T-stat = Thermostat duh!

Still I have the delimma that this thing ran without the 24 volts working... is that possible to by pass the relay that holds down the connection? I looked for some physical object that might have been used to physically hold down the connection... but I didn't see anything. Plust that would be dangerous, right?

Thanks
 

Last edited by Deekus; 05-15-13 at 07:35 PM.
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Old 05-15-13, 09:21 PM
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Yes....that would be very dangerous.

The air conditioning system works by a certain set of parameters. The compressor is directly controlled from the contactor. The contactor is a two pole electrically operated switch.

Without 24 vac the contactor can not operate. There are no two ways about it. The wiring may be disconnected now but if the system worked last year then the wiring was connected at that time.
 
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Old 05-16-13, 12:51 AM
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So how do I post a picture then?
Same way everyone else does, by either first uploading to a site such as photobucket.com or by directly uploading from your computer.
 
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Old 05-16-13, 05:37 AM
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Thanks PJmax,
A new therory is forming now. These renters have two mean agressive dogs. There are wires chewed off coming from the basement. I suspect now that the dogs have ripped the 24 volt wires out.
So, I surmise now that the 24volt transformer is in the furnace, right? and from there the thermostat signal is sent to the unit outside. I do not see any transformer outside with the AC unit. Does this make sense?
 
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Old 05-16-13, 05:42 AM
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Trying picture again Trying picture again Trying picture again Trying picture again Trying picture again Trying picture again Trying picture again....


I think I got the photo to take )
 
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Old 05-16-13, 05:42 AM
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You have to have 24V to operate the contactor, there is no other way to start the unit. Also as mentioned by Grady, low pressure switch needs to be checked too if you don't see 24V at the small wires or at the contactor terminals. (yes, the transformer is in the furnace, or we call it air handler)
 
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Old 05-16-13, 08:27 AM
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I've placed arrows where I think 24v connects to the coil. Looks like the yellow and blue wires would be the low voltage wires. It appears that yellow is connect correctly and I can't tell what blue is doing.

Name:  AC temp.jpg
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Old 05-17-13, 06:43 AM
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You may need a voltmeter to check this out.
 
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Old 05-17-13, 07:42 AM
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Buy a multi-tester, that way you can ohm the coil with all power at furnace & 240 breaker panel off; & then with furnace on, test voltage and troubleshoot the low voltage control system.

Be ultra careful, you are dealing with high 240 voltage to that contactor; only the control coil has 24-volt going to it; everything else is deadly!
 
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Old 05-17-13, 11:31 AM
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Thanks PJmax,

You were right. Yellow and blue went right there. In my picture blue had been pulled off by the renters big dogs. They must have eaten the wires outside the unit cause I never found them.

I did get it running. Once I figured out wires were missing. One thing that was difficult was figuring out which transformer wires to use. All were diff. colors and there were at least 8. I need to get some alligator clips for my meter because it was difficult getting a good connection for the voltmeter. Anyway, it was red and white that did it.

I put the new wires from the transformer in a PVC pipe and staked it to the ground and ran them up the side of the unit clamping them to the side. That should prevent the dogs routing the wires out again. I told the guy he should prevent his dogs from going between the house and AC unit or he might soon have fried dogs. I'm not the landlord, not sure if that's a landlord problem or not.
 
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Old 05-17-13, 11:37 AM
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Any idea what component that is at center top? It is underneath the top AC cover but is completely disconnected.
 
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Old 05-17-13, 01:40 PM
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At the bottom/left of the device, there are red & back wires. Is that other "thing" coming off the same corner a wire or a piece of small copper tubing?
 
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Old 05-17-13, 03:13 PM
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I'm pretty sure it is just a wire. I don't recall any copper tubing there. ....................

Here's another angle:Name:  Mystery AC piece2.jpg
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Old 05-17-13, 09:13 PM
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My first guess is that it could be one of those aftermarket 5 minute lockout timer modules.

My second thought is that it was a thermostat added to the condensor fan to cycle fan in cooler/cold weather. A device added to keep the compressor head pressure up.
 
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Old 05-18-13, 06:20 AM
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Well, whatever it is completely disconnected. Thanks PJmax.

Grady, what were your thoughts if it was a small copper tube running on the bottom of it?

Since the unit is still running okay, I doubt I get over there again to look more closely at it. But if I'm called out there again I'll check more closely.

Also, had a question about the contactor relay, when it was energized it seemed to buzz pretty loudly. Is this normal?
 
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Old 05-18-13, 06:32 AM
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The abandoned control was a 2 speed fan control. Black was for high speed and red was for low speed. The small copper tube from it senses temperature.

The OEM motor for that unit had 2 speeds. The replacement motor in that old GE condenser has a single speed.

Contactors can run for many years making that buzzing noise, but if it is bothersome replacing it is not a difficult job.
 
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Old 05-18-13, 12:57 PM
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Thanks Houston,

I'll keep that info. tucked away for future use, never know when I'll be checking another AC unit.

Being a handyman can be a pain lots of times, because I'm not a professional at anything, but it also makes it interesting to learn new things to where I can solve problems a little more cheaply. Most things I can repair, but there are those times when only a professional is going to be able to do it.

This repair worked out pretty well once PJ and some others let me know what a contactor was and that it worked off a 24 volt transformer. It is pretty cool how that relay sucks the connector down to make contact and hold there until the transformer cuts off.
 
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Old 05-18-13, 04:28 PM
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Houston, Deekus
Fan control is where I was going with the copper tube question.
 
 

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