Yet another "AC fan runs constantly" post


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Old 03-05-08, 05:34 PM
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Yet another "AC fan runs constantly" post

I swear I have torn through all of the posting. The only one that seemed to come close was this one. The problem I have is identical but it didn't seem to come to a conclusion.

http://forum.doityourself.com/showthread.php?t=236546

I have a Amana/Goodman VCA30C2C AC unit and an American Standard Freedom 90 UX1B080A9421A furnace. My house is also zoned (2) with a Honeywell EMM-3 MiniZone panel.

The quick summary, since it is identical to the other post, is that the condenser AND fan run constantly. If I set either of the thermostats to COOL the blower comes on and cool air comes out. The house cools, the blower shuts off, but the condenser and condenser fan keep running. The only way I can shut it off is if I via the breaker.

From the other posts I've checked the contactor on the AC unit and it is working. I tested it by leaving the cover off, turned the power back on, and the contactor was "contacted". Also the zoning panel system LED shows when there are calls for heat and cool. There are no indicators on the panel that there is a problem. I do have two transformers. One is in the furnace and one is near the breaker box. I've tested the connections with a voltmeter and each are putting out power.

Here's the twist. I noticed this problem with the AC running all the time AFTER I replaced a pressure switch in the furnace. I can't tell you if the AC had this problem before or after I replaced the pressure switch. I'm wondering if while I was replace the pressure switch I touched a wire the wrong way and blew a relay or something similiar? I do know that I turned the power off at the breaker when I was working on the furnace.


I have pics of the unit and wiring but can't seem to add them to the posting. I'd be happy to email them to anyone who would like to take a look. Here is the link for the zone panel and my furnace. I have not been able to locate the manual for the AC.

***Funace***
http://www.americanstandardair.com/H...es_AUC_ADC.pdf

***Zone Panel***
http://customer.honeywell.com/techli...it/68-0237.pdf

I can't begin to say thank you for those who read, attempt, and maybe even solve my issue. It will be a great relief to get this fixed.

Thank you ! ! !
 
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Old 03-05-08, 06:32 PM
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A most weird problem.

First things first: when you say the condenser and the condenser fan motor keep running I take it that you mean the "compressor" and the condenser fan motors...in other words, the two motors that are part of the unit that is installed outdoors. Please confirm

If this is the scenario you have there, it is a wonder and a miracle that you have not lost your compressor motor yet.

Try the following first:
From the thermostat, turn the system switch to OFF (the one that reads COOL-OFF-HEAT) and the fan switch to AUTO (the one that reads AUTO-ON).
Under normal circumstances, this should turn everything OFF, both, outdoors and inside the house.

If the outdoor motors (compressor and fan) are still ON, remove the cover, look for the contactor coil and pull/disconnect the YELLOW thermostat wire. This should de-energize the contactor coil, forcing its contacts to open and turn both motors OFF. Please confirm.

I'll be looking forward to your feedback.
 
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Old 03-05-08, 07:16 PM
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Reply

Thank you for the quick reply. I attempted to answer your questions the best that I could below.

First things first: when you say the condenser and the condenser fan motor keep running I take it that you mean the "compressor" and the condenser fan motors...in other words, the two motors that are part of the unit that is installed outdoors. Please confirm

My bad. Yes the two motors in the unit outdoors runs constantly. I've left the breaker in the off position so the unit hasn't been running.

Try the following first:
From the thermostat, turn the system switch to OFF (the one that reads COOL-OFF-HEAT) and the fan switch to AUTO (the one that reads AUTO-ON).
Under normal circumstances, this should turn everything OFF, both, outdoors and inside the house.

If the outdoor motors (compressor and fan) are still ON, remove the cover, look for the contactor coil and pull/disconnect the YELLOW thermostat wire. This should de-energize the contactor coil, forcing its contacts to open and turn both motors OFF. Please confirm.


I set the thermostat to Off and Auto and yes the compressor and fan motors on the outside unit are still running. I want to double check before I disconnect the yellow wire. You want me to disconnect it while it's running? I have done numerous electrical projects (not much with air cond. and 220 lines) and I try my best to do the safety first thing. Is it required that I do it while it's running? I've included a pic. I circled the two yellow wires that I see. I just want to make sure I disconnect the right one.

 
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Old 03-05-08, 07:50 PM
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Trying to be proactive

Thought I would post these just in case they are helpful.

Zone Panel



Furnace Wiring
 

Last edited by Cassidy72; 03-05-08 at 07:56 PM. Reason: fix pictures
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Old 03-06-08, 01:54 AM
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Originally Posted by Cassidy72
I want to double check before I disconnect the yellow wire. You want me to disconnect it while it's running? I just want to make sure I disconnect the right one.
You may disconnect that very same wire, which feeds one of the two terminals of the contactor coil, before turning the circuit breaker back to the ON position. Then, switch the breaker to ON...the motors should remain OFF. This would eliminate that contactor as the source of trouble.

Finally, with power still ON, touch the terminal of this yellow wire to the point from which it was disconnected. I expect the contacts of the contactor will pull in. You're handling here only 24V, nothing to be worried about.

My feeling is that you have a problem either at the furnace's board or the EMM zone controller, but want to put the condensing unit's contactor out of the way as the source of trouble.

Nice pics.

BTW, I had to ask: you have a top notch, 92.1% efficient,condensing-direct vent furnace indoors, matched to a seer-10 condensing unit outside, which is as low as it gets. How come?
 
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Old 03-06-08, 04:51 AM
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Talking

You may disconnect that very same wire, which feeds one of the two terminals of the contactor coil, before turning the circuit breaker back to the ON position. Then, switch the breaker to ON...the motors should remain OFF. This would eliminate that contactor as the source of trouble.

Finally, with power still ON, touch the terminal of this yellow wire to the point from which it was disconnected. I expect the contacts of the contactor will pull in. You're handling here only 24V, nothing to be worried about.

My feeling is that you have a problem either at the furnace's board or the EMM zone controller, but want to put the condensing unit's contactor out of the way as the source of trouble.


Done and it did exactly as you said. The contactor clicked shut when I touched the wire back to the tab.

BTW, I had to ask: you have a top notch, 92.1% efficient,condensing-direct vent furnace indoors, matched to a seer-10 condensing unit outside, which is as low as it gets. How come?

It came with the place

I think you are right as I have the same feeling that it is something simple somewhere. I'll be honest and say I also have the nagging feeling it is something I did. Something simple that I didn't think much about when I did it and thus forgot I did it. Last night I couldn't help myself so I disconnected the Rh and Rc wires at the panel just to double check the connections. I found out that I was incorrect when I said I had two transformers. I was unscrewing it and since it is in a bad place that I can't see all that well a jumper fell out. Thus it is all connected to one transformer in the furnace.

Not sure if this helps but I left the jumper off and turned the power back on and sure enough, with the AC unit's breaker ON the fan(s) were NOT running. As soon as I put the jumper back in the fan started running constantly again.
 
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Old 03-06-08, 08:39 AM
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Wiring Scheme

Maybe this will help. If not atleast it help me get my head around the wiring. I'm thinking the next thing I need to do is put a multimeter on the connections while the system is in cool, heat, and maybe even in the off position. I can also put the meter on the AC Unit in each of the scenarios.


 
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Old 03-06-08, 10:00 AM
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EMM-3 miswired

Notice the pic below
The 3 green LED's lit tells that "3" zones are calling for cooling (curious, since you only have 2 zones). There's a miswiring here, but let's go step by step.



notice the red arrows and text pointing at thermostat cables T-stat-1 and T-stat-2.

Notice the thermostat cable I have called Ghost??? I see a Red wire connecting to either terminal Rc or Rh on EQUIPMENT on the left of the EMM-3 (the pic is not clear) and a White wire connected to C on ZONE PANEL TRANSFORMER on the right of the EMM-3. Disconnect them both. It appears that Ghost only has these two wires hooked up to the EMM-3. Please confirm.

Put a jumper between terminals Rc & Rh on EQUIPMENT at the EMM-3

From the gray thermostat cable I've called T-stat-1, the following wires Red(R), Yel(Y), Whi(W) and Grn(G) should each connect to ZONE-1 terminals of the same label (R, Y, W & G) on the EMM-3. No other wires should connect there from nowhere else to the terminals just mentioned. Same deal for the cable I've called T-stat-2. This appears from the picture to have been done correctly.

From the gray thermostat cable I've called To furnace, the following wires Red(R), Yel(Y), Whi(W) and Grn(G) should each connect to EQUIPMENT terminals of the same label (Rh, Y, W & G) on the EMM-3. Wires Blu(BU) and Brown (BR) connect to ZONE PANEL TRANSFORMER terminals R & C on EMM-3. No other wires are welcomed here.
The other end of cable To furnace ends in the furnace's terminal board. Make sure Rh, Y, W & G go to the terminals having the same labels (R, Y, W, G). The BU wire also connects to R there, while the BR connects to C on the furnace terminal board.

I don't know what that Ghost cable is doing there...please explain if you know.
 

Last edited by pflor; 03-06-08 at 07:08 PM.
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Old 03-06-08, 12:24 PM
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EMM-3 wiring schematic

Just in case the components I mentioned in my previous posting are not well labeled on the EMM-3 itself, this should help:

 

Last edited by pflor; 03-06-08 at 07:10 PM.
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Old 03-06-08, 12:28 PM
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pics - no pics

Finally got the pictures. Hope they help

Here at work, the firewall prevents any picture files from opening on our P.C. screens. I have loaded two pics but I have no way of telling if they were really uploaded and you're able to see them...I hope so...else tonight after I get home I'll post them again.
 

Last edited by pflor; 03-06-08 at 07:11 PM.
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Old 03-06-08, 07:41 PM
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Ghost wire understood

O.K. now...
I was just able to see your hand-made schematic (the one on graph paper) I can now see where this ghost cable comes from...it comes from the condensing unit outdoors. These two wires end up on the contactor coil terminals of the condensing unit outside the house. They have to be fed 24V on a call for cooling from the furnace's terminal board. Who makes that call? terminals Y and C on the furnace's terminal board.

Well then, the red wire in this ghost cable gets connected to the C terminal on the furnace terminal board, while the white wire from the ghost cable gets connected to the Y terminal on the terminal board.

this should take care of your problem...I hope
 
  #12  
Old 03-07-08, 12:22 AM
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Too much AC

The control wires to the condensing unit as you have realized are being fed 24v constantly as you have identified the problem starting when you worked on the furnace let's start there follow the two control wires in to the furnace and see if the stripped back area on one of them is up against the control wire going to the R terminal, if this is not the issue or just to simplify in cooling the Y terminal on your furnaces control board is just a place to tie the wires together you can take the wire off Y that comes from the condensing unit and the wire coming from your Y terminal on your thermostat/EMM and tie them directly together then if the problem continues you know that it has nothing to do with your furnace work but when something like this happens with control wiring always try to seperate the possibilities into smaller "bite size" chunks you have already determined the problem is not outside what I have told you will tell whether or not the problem is in the furnace, if not go to thermostat and take off the wire on the Y terminal if it still persists that leaves only the EMM
 
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Old 03-07-08, 01:22 AM
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alternate and SUPER QUICK solution

Cassidy:
Alternatively to my instructions on posting #11, and to simplify/expedite things, you already have the white wire from the ghost cable connected to the C terminal in the EMM-3 (you may leave it where it is).
The only other thing left to do then, is to disconnect the red wire from the ghost cable, currently connected to the Rh on EQUIPMENT, and reconnect it but this time to the Y terminal.

But remember, since you have only one transformer, there must be a jumper between terminals Rc and Rh at EQUIPMENT.

In retrospect, and to sum things up, the only problem you've had here all along is having that red wire (from the ghost cable) connected to the Rh, which is NOT its proper place, instead of the Y terminal (its rightful place)

Let us know how things worked out
Happy heating & cooling!
 
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Old 03-07-08, 07:53 AM
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Talking Fixed ! ! !

I think you are right as I have the same feeling that it is something simple somewhere. I'll be honest and say I also have the nagging feeling it is something I did. Something simple that I didn't think much about when I did it and thus forgot I did it.

I knew I did something wrong when I was troubleshooting the pressure sensor problem. I remember taking off the zone panel cover and saw that one of the wires had come off. I can't remember which. I assumed it went back to the spot that didn't have one. It must have been the red wire on the Rh.

I moved the red wire to the Y connection on EQUIPMENT as you recommended and sure enough the AC unit didn't start after I turned the breaker back on. I turned the thermostat to COOL and the AC unit came on like it should. It works perfectly.

Thanks Pflor (you too Mike) for taking the time. I sincerely appreciate it. Not sure what I can do in return. Maybe if you ever need a reference on your resume
 
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Old 03-07-08, 08:25 AM
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Glad to read that you have that baby up and running again as it should.

BTW, lucky miswiring this time around, as hooking up a wire into the wrong spot could possibly cause serious damage (a burnt board, thermostat, gas valve, etc).
 
 

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