Two Outside AC Blowers Stopped Working Same Time

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Old 08-20-13, 03:06 PM
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Two Outside AC Blowers Stopped Working Same Time

So I installed a second Honeywell wi-fi Thermostat and a few days later both outside blowers stopped working. Previous to this thermostat, I had installed an identical unit and everything was fine for a year. Both are identically wired.

My first thought was the capacitors. But that does not make sense if they both go bad at the same time. I reset both circuit breakers. Still nothing.

I'm confused how two separate units can work inside by outside they are not?

Outside units are Rheem Corsaire - not that it really matters.
 
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Old 08-20-13, 03:58 PM
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Welcome to the forums.

Are these two completely independent air conditioning systems... like upstairs and downstairs ?

The outside units are called the condensors and the inside units are called the blowers or air handlers.

I take it that both condensors are not working. How about the inside blowers ?

You may need a voltage checker or voltmeter to sort thru the problem. You need to find out if both the air handlers inside have power and if both condensors outside have power. They may have shared power between them at some point which you'll need to find.

I don't know much about the wi fi thermostats.....are they interfering with each other ?
 
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Old 08-20-13, 04:51 PM
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Yes, two separate systems, one for upstairs and the other downstairs. Both inside blowers work fine as does both thermostats. The wi-fi works fine - no interference.

The wiring is separate on each and on their own fuse switch. But I'm not discounting that something is shared, which might prove difficult to prove.

I guess I will check the outside voltage for both. Was it 24v?

What if there is no voltage - work backwards back to the inside blower panel?

What if there is voltage? What are the odds of two Capacitors going bad at the same time.
 
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Old 08-20-13, 05:27 PM
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No....both capacitors didn't go at the same time.

The 24vac is not shared between the units.

The 240 vac may be shared between the units. You need to check for 240 VAC at the disconnects outside at the compressors. Work back from there.

Be careful .... high voltage.
 
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Old 08-20-13, 06:12 PM
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I'm guessing I will not find the voltage. Does that mean there is a short?
 
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Old 08-20-13, 06:23 PM
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It could mean a short but more than likely the two units may be running off of one large breaker in your panel instead of two large breakers.

Each one should typically be on it's own two pole 30amp breaker. You may find both on a single two pole breaker. .... maybe like 40amps. Just a guess on size.
 
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Old 08-20-13, 06:42 PM
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Yeah, they each have their own breaker panel outside. But one has an on/off switch and the other one looks weird - maybe you pull it out - not sure.
 
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Old 08-21-13, 05:25 AM
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I disconnected the wiring from the more recent inside blower with same results - no change. Now to the outdoor wiring with my multimeter.
 
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Old 08-21-13, 06:11 AM
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You have turned the breaker in house breaker panel for the two sub panels/disconnects all the way off then on haven't you?

'm guessing I will not find the voltage. Does that mean there is a short?
No, absence of power is called an open, the opposite of a short where you do have power but in the wrong place till the overcurrent protection device (breaker, fuse) opens the circuit.

other one looks weird - maybe you pull it out - not sure
Yes, a pull out disconnect. Does it have fuses?
 
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Old 08-21-13, 07:21 AM
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I tested two wires at the contactor and get 25v.
 
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Old 08-21-13, 07:27 AM
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Yes, first thing I tried was reset both breakers which did nothing.
 
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Old 08-21-13, 07:45 AM
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With the thermostat calling for cooling, you should measure ~24VAC on the coil (low voltage) side of the contactor, so that sounds right. You should measure ~240VAC coming into the contactor (wires coming in from outside disconnect), and ~240VAC on the output side of the contactor (if thermostat is calling for cooling and contactor is good).

Check for ~240VAC on both ends of the contactor (normally high voltage terminals are on long ends of contactor), with thermostat calling for cooling. If you have it on one end but not on the other, the contactor is likely defective.
 
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Old 08-21-13, 08:11 AM
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What is the likelihood that this would happen on both units at the same time?
 
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Old 08-21-13, 08:40 AM
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Single Pole Contactor has no reading. I checked the two thick black/red wires on top and also the two thick black wires on the bottom.

I did not check the second unit but I can only conclude the same without testing.

Now I'm confused because how can two contactors go bad at the same time. I find that doubtful.
 
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Old 08-21-13, 08:59 AM
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You're jumping around.

You need to check for 240 VAC in the disconnect boxes outside on the wall next to the condensors. It's not going to be a 24vac problem because each of your units is separated.

If you don't find 240 VAC in the outside disconnects then you'll need to open the panel and check at the breakers.

Your problem is NOT the air conditioners...... it's the power coming to them.
 
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Old 08-21-13, 09:03 AM
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Since you have no voltage at the input to the contactor, it's likely not the problem. For some reason, it appears that you have no power going to the outside unit. Without knowing how your outside power is wired, I can't help you much other than to say to try to check it out step by step. First, check to see if you have power going to the outside shutoffs. If you do, then check to see if you have power coming out of the shutoffs.
 
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Old 08-21-13, 09:15 AM
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I checked the second unit and it has 28v at the contactor and zero on the higher and lower thick wires.

Checking the power at the box sounds like a good step. But where are the terminals to test?
 
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Old 08-21-13, 09:22 AM
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You said one was a pullout disconnect. Pull the handle out and you should see the four contacts.Two up and two down. Two should have 240 vac on them and two will not show any voltage.

That on/off switch may be a breaker or a non fused shutoff. There will be a cover over it usually with one screw. Remove the cover to see the wiring.
 
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Old 08-21-13, 09:27 AM
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Will do. But for other people that stumble upon this thread, here is a nice video explaining:

http://www.youtube.com/watch?v=REw7JT4d0J4
 
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Old 08-21-13, 09:38 AM
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So I checked the breaker terminal on both the incoming and after fuse terminals just on one unit. I get zero. But I hear the hum next to me from the contactor area. That must be the 25v.

So, now where do I check?

The only thing left is the breaker panel which I reset several times.
 
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Old 08-21-13, 09:46 AM
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Problem fixed but not sure why. I went back to the house breaker box again and flipped both switches off. This time I waited a few seconds before flipping them on - "hummmmm". Back in business!

Thanks for the lessons and learning experience.
 
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Old 08-21-13, 11:06 AM
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So did you finally read my post?
 
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Old 08-21-13, 11:07 PM
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That's a nice link on a service disconnect but it's just one of like five or six different designs. Most service disconnects don't have fuses in them.


Ok.... your A/C's are working now but you didn't find out why they stopped working. You flipped breakers. Do you know what you were flipping ? Like what sizes ?

If you only have that main panel and two air conditioner systems then you should have, at least, four (4) two poles breakers. Two for the compressors and two for the air handlers. You may have gas furnaces and then they might not use two pole breakers in the panel.

My guess is they put both compressors on the same breaker in the panel which means the problem will happen again...... and with time will happen more often.
 
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