Outside ac fan runs non stop

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  #1  
Old 08-13-13, 05:41 AM
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Outside ac fan runs non stop

Hello everybody.
I'm new here.
Have been looking Online to determine why my out door ac fan won't stop, even when the inside tempareture reaches desired level and the thermostate stops!
I checked the contactor and caps and all looks ok, HOWEVER:
after reading some posts, I came to think that the contactor is probably wired incorrectly....
Here is a picture as I found it:Name:  contactor.jpg
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As many posted, the BLACK wire is SUPPOSED to be on the TOP LEFT side, correct?
My querstion is:
Does this wiring look correct?
Thank you all for reading and thank you all in advance for helping out.

Contactor specs as follow:
2poles/24volts/40amps
 

Last edited by Hotovaga; 08-13-13 at 05:56 AM.
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  #2  
Old 08-13-13, 06:24 AM
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I'm assuming it was working correctly at one time. Have you replaced any components (capacitor or contactor) recently? Wires don't magically move themselves. If you haven't replaced any components (or moved any wires), I would be suspicious that the contactor contacts are welded together (always on).

If you have a voltmeter, with the thermostat off (not calling for cooling), check to see if you have ~240VAC between the two terminals at the top of the contactor (red & black wires). If you do have 240VAC there, then check for voltage between the two side terminals (appear to be brown wires). You should have 0 volts. If you do have 0 volts, your contactor is defective (contacts welded together). If you measure ~24VAC, then something is wrong with the thermostat or it's wiring.
 
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Old 08-13-13, 12:37 PM
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Thanks Bob14525.
Just followed your tips and here are the findings:
-The bottom wires read 248 volts (!)
-The top ones read 0 volts, and
-The side ones read 0 volts.
So,
The contactor is the culprit?

Thanks again.
 
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Old 08-13-13, 12:41 PM
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@Bob14525:
Further understanding and clearing my reply to urs, I DID NOT have any voltage on the top wires let alone the ones on the side.
 
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Old 08-13-13, 12:44 PM
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No, since you're reading 0 volts at the top of the contactor and the thermostat isn't calling for cooling, the contactor is working correctly (at least the contacts aren't welded together). If the condenser fan is still always running, then it would appear that something may be miswired. Has someone recently done work on your outside A/C unit? The only thing I can suggest is (with the power turned off), check where the fan wires are connected. If one or more of them are connected to the bottom of the contactor, that is likely the problem. The fan wires need to be connected to the top of the contactor so that they only get power when the thermostat is calling for cooling (contactor is enabled).
 
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Old 08-13-13, 06:17 PM
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The condition you are describing can only happen if the contactor contacts have become welded shut or the contactor's low voltage side is being fed 24VAC non-stop. If you suspect a stuck contactor a 100% accurate test is to turn off the power to the indoor section. This action removes control voltage to the condenser. If the condenser fan keeps running then the contacts on your contactor are either welded together or have an insect or something else not letting the plunger function as designed. I have seen bad thermostats cause 24VAC to be sent non-stop to the contactor keeping it energized.
 
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Old 08-13-13, 06:40 PM
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try this, turn off the power on outside unit, discharge the cap with a screw driver, put the multimeter on Ohms to measure the resistance, now put one lead at the bottom left, and the other at the top left of contactor. Repeat the same thing for the right side. The reading if the contactor is OK should be very big number or infinite on both sides. If you read 0 or small number on either side than the contactor is bad.
 
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Old 08-13-13, 09:15 PM
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Guys.....keep in mind.....most of the contactors in these units are only single pole. The second pole is carried thru. That means one side of the fan is always hot.

If the condensor fan winding gets a short to ground..... it can run with the contactor open.

In one of your previous posts you wrote that the contactor was a 2 pole model. If that was actually two switching poles my idea would be invalid.

If you remove the cover from the contactor points you can verify single or double pole switching. When you checked power on the top two wires.....did you check between each terminal and ground also ?
 
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Old 08-14-13, 07:42 PM
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Talking Waiting for a new contactor to be tested tomorrow:

To:
PJmax,
cat4500,
firedawgsatx, and
bob14525:
It's a 2 pole contactor. Definite purpose. 24VAC, 40amp. It's a reading from the sticker.
I ordered a contactor and Grainger will have it for me tomorrow...(none of it's store had it in stock).
So, I'll follow up with all of you with my finding, after I change the contactor.
Until then, thanks a lot. A LOT!!!

BTW, I got a bit confused though, after reading that the top and side wires showing no or 0 volts (when the inside unit is NOT calling for cooling) means that the contactor is healthy.
I wonder, then, what would be the sign(s) that the contactor is WELDED?
Forgive my ignorance.
I'm not an educated person in electrical engineering, and I'm used to ask a lot for foregiveness....
 
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Old 08-14-13, 07:53 PM
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f you remove the cover from the contactor points you can verify single or double pole switching. When you checked power on the top two wires.....did you check between each terminal and ground also ?
You said you had 0 volts on output (load) side of contactor. If that was 100% true then the fan could not possibly run. That's why I asked the question above.
 
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Old 08-15-13, 09:54 AM
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To further clarify my findings, here it is once again:
-The thermostate was on off position (not calling for cooling)
-The air handler's fan was off and so was the fan for the compressor (outside)
-The feeding 2 poles (at the bottom of the contactor) shown 248 VAC
-The top 4 pins (both orange and blue and black wires) shown 0 VAC
-The 2 side wires (brown-yellowish) shown 0 vac.
AND, the fan came on when the thermostate set for cooling....!

Do you guys think there would be a difference in finding if I have the inside unit running?
 
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Old 08-15-13, 10:06 AM
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AND, here is what I found:
-The inside air handler running
-The outside compressor engaged and fan running
-Reading at the bottom wires show 244VAC
-Reading at the top wires show 244VAC
-Reading on the side wires show 25VAC

What do you guys make of this ?
BTW, I've the new contactor in hand.
Should I go ahead and replace the contactor?
Thanks again for all the feedbacks...
 
  #13  
Old 08-15-13, 10:26 AM
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If everything is working normally, when the thermostat is calling for cooling, you should have ~240VAC at the top terminals (output side), and ~24VAC at the side (control) terminals of the contactor. When the thermostat is off (not calling for cooling), you should have 0VAC at both the top and side terminals of the contactor.

From what you said in your last two posts, that is exactly what you have (voltages are normal). What is confusing to me is that in your last couple of posts you said that when the thermostat was off, both the air handler and condenser fans were off (as they should be). However, this is not what your original post said- that the outside (condenser) fan runs continually, even when the thermostat is off.

So, do you still have the problem of the outside fan continuously running?
 
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Old 08-15-13, 10:43 AM
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@ Bob14525:
Yes, back to my ORIGINAL post: The outside fan keeps running even when the airhandler's fan if turned off due to the inside temperature is achieved...
NOW:Just replaced the contactor. The readings are:
-Bottom wires show 244 VAC
-Top wires show 240 VAC
-The side wires show 25 VAC, AND
INSIDE (air handler fan) is OFF, BUT
OUTSIDE fan is running....
Back to my WIRING delimma:
Although wires do not move magically,
Are they set properly?
Someone in one of the posts for similar issues said that the BLACK wire should be on the LEFT side.
I'm very very
 
  #15  
Old 08-15-13, 11:05 AM
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No, with the new contactor in place, my main concern is that the outside fan is being fed constantly, and that' has to do with the WIRING issue.
Any help on this?
 
  #16  
Old 08-15-13, 11:06 AM
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The side wires are the control voltage coming from the thermostat. When the control voltage is 0V, the contactor should be turned off and you should read 0V at the output (top) terminals of the contactor. When the control voltage is ~24VAC, the contactor should be enabled (on) and you should be see 240VAC at the output (top) terminals.

If you're measuring 25VAC at the side terminals when the thermostat is off, something is wrong with either the control voltage (thermostat) wiring, or you have a bad thermostat.

Here's something to try. Turn off the power to the outside unit. Remove one of the control (side) wires from the contactor. Turn the power back on. Does the outside unit fan turn on? If it does, you may have a wiring error in the fan circuit. However, if the fan isn't running with one of the control wires removed, then the outside unit wiring is probably okay and the problem may be with the control (thermostat) circuit.
 
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Old 08-15-13, 11:20 AM
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@Bob:
Following ur suggestions, here are the findings:
-Turned off thermostate and the fan outside turned off, both the top and side wires showing ~0VAC.
-With one of the side wires unplugged and thermostate ON position, the outside fan DID NOT come on.
-With one of the side wire unplugged, thermostate on ON position, the air handler fan came on.
What do u make of this so far?
 
  #18  
Old 08-15-13, 11:27 AM
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You wrote:
Following ur suggestions, here are the findings:
-Turned off thermostate and the fan outside turned off, both the top and side wires showing ~0VAC.
-With one of the side wires unplugged and thermostate ON position, the outside fan DID NOT come on.
-With one of the side wire unplugged, thermostate on ON position, the air handler fan came on.
What do u make of this so far?


Everything appears normal. However, you said that when you turned off the thermostat, the outside fan turned off. I don't understand what the problem is, as this is the way it's supposed to work. I thought the outside fan was running continuously.
 
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Old 08-15-13, 11:38 AM
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@Bob:
Pls don't get me wrong.
Either you are not reading what I'm trying to convey, or I'm not being able to convey what my problem is.
Yes, when I trun the thermostate off 'MANUALLY, meaning no matter what the asking temperayre is, both the air handler and the outside fan turn off.
BUT:
When the air handler fan turns off AUTOMATICALLY due to the inside tempareture reaching the asking level, the outside fan keeps runnig.
 
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Old 08-15-13, 11:47 AM
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Question

I'll try to make this simple:
Problem: My ouside fan runs non-stop even when the air handler fan stops as the inside temperature is achieved (thermostate set @ 75 degrees).
Possible cause(s):
-Bad contacor.
Solution:
Replaced it.
-Bad thermostate:
Solution: (Observation)
It corresponds with the air handler and the outside unit. Because, it turns "ON" or "OFF" the air handler AUTOMATICALLY when the set temperature is needed or reached. Outside fan won't STOP though.
BUTIt will "TURN OFF" the outside fan IF it is switched to "OFF position MANUALLY.

AND, my problem is:
My outdoor fan doesn't stop!
 
  #21  
Old 08-15-13, 11:52 AM
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Everything appears normal. However, you said that when you turned off the thermostat, the outside fan turned off. I don't understand what the problem is, as this is the way it's supposed to work. I thought the outside fan was running continuously.

Read more: http://www.doityourself.com/forum/ai...#ixzz2c46nwz00
@Bob:
Shouldn't the outside fan stop automatically when the air handler stops?
 
  #22  
Old 08-15-13, 11:59 AM
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This appears to be a problem with the thermostat. It seems that in "manual" mode the system works correctly but in "auto" mode the condenser fan continues to run. I would pull the thermostat off the wall to expose the sub-base terminals and wiring. Inspect the wiring to insure none of the wires connected to the terminals are touching each other. If you pull the thermostat wire from the "y" terminal does the condenser fan shut off?

There are two main reasons for the outdoor fan to remain on while the system inside is off . The first is that the contactor on the outside condensing unit is welded closed. In this case the 240 volts supply to fan and compressor will not be turned off when the inside system goes off.

The second is that 24 volts is still be supplied to the outside contactor even though the thermostat is satisfied. The 24 volts would be supplied by an electrical short between the red and the yellow wires . The short could happen any where along the thermostat wiring where the two wires have become bare and are touching.

In your case. it doesn't appear the contactor is welded since it shuts off manually. That leaves the thermostat. Probably an internal relay issue.
 
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Old 08-15-13, 12:03 PM
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OK, I think I understand now. Sorry it took me so long to understand what you were saying. If the outside unit doesn't turn off when the temperature reaches the set point, but it does turn off when you set the thermostat to the "OFF" position, it's likely a bad thermostat. There are normally relays inside the thermostat that connect the proper terminals together depending upon the thermostat setting. For cooling, there should be two relays, one that connects RC to Y (turns on outside unit) and another that connects RC to G (turns on blower). It would appear that the relay that turns on the outside unit is sticking. My guess is that a new thermostat will solve your problem.
 
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Old 08-15-13, 12:10 PM
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Just pulled out the thermostate from the base unit (connected mounted on the wall), and the ouside fan stopped!!!
All the wires on the base pannel seem to tightly screwed (No, not THAT type of SCREWING), not touching each other.
The major finding here is, once the control panel (snap on panel) is removed from the BASE panle with all the wirings are, the fan out side stops!
 
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Old 08-15-13, 12:25 PM
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Ok,
As I just posted my finding with the controln panel being pulled out, the out side fan stopped and, putting it back on the base plate, the fan came back live.
NOW,
Here is the inside wiring AS it is now.Name:  Thermostate.jpg
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Old 08-15-13, 12:29 PM
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Pls note that there are 6 prongs on the control panel as there are 6 wires or SCREWS on the base panel, but the right prong on the base unit (Y1) is not WIRED!
 
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Old 08-15-13, 12:41 PM
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Just a thought. If the thermostat batteries are low it can cause the system to operate abnormally. I would install some fresh batteries in the thermostat and see if that makes a difference.
 
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Old 08-15-13, 04:22 PM
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If you want to rule out the thermostat as the problem, you can temporarily jumper between the thermostat terminals RC and Y. This should start the compressor (outside unit), however, it will not turn on the air handler blower. You don't want to run it that way for more than a few minutes or you'll freeze up the evaporator coil. If you want to force the inside blower to come on, place a jumper between terminals RC and G. If the system works with RC jumpered to Y and to G, it would seem your thermostat is defective. If you have an old thermostat lying around the house you can install it to see if it resolves your issue.
 
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