Carrier Air Handler Fan will not shut off.


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Old 09-20-14, 11:57 AM
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Carrier Air Handler Fan will not shut off.

Hello, not sure if Houston204 still on the forum, but I seen some old post with the same issue I'm having and was wondering if I could pick your brain. I tried to send a PM but his box is full.
I do all my own maint., I'm new to the forum, and I refuse to call in a HVAC Tech. So many bad ones out there ruins it for the legitimate ones.
I've got some pics of my wiring diagram and I can tell you what I've done. I removed the wires from the thermostat, fan runs. I replaced the PC card which has the fan relay, no help. If I remove the double black wire spade on FR it shuts down. I was thinking maybe it was the sequencer, so I tried to just remove the wires to the heat elements, but that disabled the system.
My a/c is working fine, just that the fan won't shut off.
Any help would be appreciated.
 
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Old 09-20-14, 12:10 PM
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I am an HVAC Tech, but I have seen some bad ones.

What is the model number of the air handler?
If the fan cycles correctly when you unplug the blue wire on NC it points to the sequencer.

 
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Old 09-20-14, 02:15 PM
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First off, thx for the prompt reply. I'm not against all HVAC tech's. Some the corrupt ones. I'm at work now so I can't get the model #. The diagram you show is close to what I have. My diagram inside of unit on side of fan cage doesn't include the heat elements I have. You diagram shows 3, so I used that last night to t/s. When I pull off the blue wire at NC, the fan continues to run.
 
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Old 09-20-14, 02:23 PM
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My air handler is a updraft. I have a tank and float for moisture off of "A" coil. On my PC card, I have a red wire that splices into a 2 conductor thermostat wire and runs down into box under air handler. If I unplug that wire on PC card, blower stops, but then it renders my a/c inop. My print doesn't address that wire.
 
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Old 09-20-14, 04:11 PM
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It sounds like your sequencer is not the problem and your float switch is wired correctly.

Does the fan turn off if you disconnect the G wire? It is usually a green wire from the stat connected to a grey wire from the air handler.
 
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Old 09-20-14, 04:51 PM
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Ok, its grey at the PC card. No, I pulled it and it doesn't shut it down.
 
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Old 09-20-14, 04:57 PM
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I've pulled all the connections at PC card, brown, at the "C" position, grey at the "G" position, red at the "T" position, with no effect on fan. Only when I pull the red at "R" position will it shut down. This is the wire that goes down to float switch. 1st thing I did was switch thermostat off, no effect on fan.
 
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Old 09-20-14, 07:37 PM
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You have proven that the control board is not getting a signal to run the fan.
You have proven that the sequencer is not running the fan.

Remove the wire nut connection from your stat to the air handler W wire.
 
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Old 09-21-14, 12:02 PM
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I apologize for the delay. Checked for a grd in area you suggested. Everything is good. Your pic looks identical to my model. 2 sets of thermostat wire with a white in each ganged to a white that turns into a violet after connector which goes to the sequencer. These separated fan still runs.
A white ganged with 2 reds, 1 red goes up towards thermostat, other red goes to outside unit, and the white goes with a red, not ganged with it, down towards the box under, assuming its for the float switch. That allows fan not to run.
I'm thinking that did the same as before when I disconnected the red for float switch.
Any and all help is appreciated.
 
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Old 09-21-14, 01:58 PM
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A float switch wires in series with one of the 2 wires to the outdoor unit or the R wire to stat.
Verify that your air handler red connects to float switch red, float switch returns as a white wire that connects to stat red and condenser red.

The only 2 signals that bring in the fan are G and W.
The fact that disconnecting R turns off the fan tells me that we are missing something.
Try disconnecting G at the wire nut connections in the area at the top right of the pic.
 
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Old 09-21-14, 02:22 PM
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I suggest you confirm the wires are connected to the appropriate terminals as shown on the wiring diagram:

NO: Black wire relay number 1 (out of plug)
NC: Blue wire from relay number 1(out of plug)
SPT: Lead from blower motor

If those are properly connected then you can test voltage at terminals 2 and 4 on Relay 1.

While blower is running turn off power to air handler. Remove wires from SPT and NO terminals and check for continuity between the two terminals.

If it shows continuity across SPT and NO terminals the fan relay is stuck and causing your problem.
 
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Old 09-21-14, 04:49 PM
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Turn the power off remove the line voltage conductors from the PC board ,turn the power on and check for continuity between STP and the terminal that the black wire was removed from (N/O)should be open when the fan switch on the Tstat is off and no other function is calling.
The new board could be bad.
Geo
 
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Old 09-21-14, 06:58 PM
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Ok, Geochurchi, the checks you suggested are good.
 
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Old 09-21-14, 07:11 PM
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Geochurchi, the line voltage conductors on PC card. You were meaning the 2 red wires, correct. 1 is 23 vac from xformer and the other 1 is from thermostat with the thermostat turned off
Turned on thermostat to cool; then I reconnected them 1 at a time, when I installed the red wire on terminal T my outside compressor kicked on. When I installed the red wire on R the FR still showed open across SPT and NO. So I reinstalled the wire to blower on SPT and then the light blue wire on NC and then the double blacks onto NO and this time the fan stayed off. So we turned desired temp down a degree, and this time everything worked correct. In just a few minutes I'll know if the fan is going to shut off.
 
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Old 09-21-14, 07:14 PM
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Ok, for the first time in a week, the fan kicked off like its suppose to. Now; something was hung up, a contact somewhere, not releasing. Is their a time delay relay on the outside unit PC card that keeps the fan in air handler running for a period of time after the compressor kicks off?
 
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Old 09-21-14, 07:18 PM
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firedawgsatx, the checks you mentioned were all good. All my wires were correctly placed.
 
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Old 09-23-14, 04:41 PM
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Did it shut off eventually?That could be a function of your thermostat,what type of Stat are you using?some setting will allow the blower to continue to run for a bit after a heating or cooling cycle is complete.
Geo
 
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Old 09-24-14, 07:06 AM
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Yes, long story. CPI security installed a digital thermostat @ a year ago. I had noticed there was a fan legend displayed, running. Numerous times I turned power off to air handler and compressor while troubleshooting. I pulled thermostat off, swapped in upstairs one, fan stayed off. Reinstalled original one, me with meter at air handler PC card, wife at c/b panel, daughter at thermostat. As I called out to each, power on, I was checking across FM relay, this time with power on. Everything was playing right. My daughter said thermostat showed the legend auto above fan. This hadn't showed before. Everything worked correct. Somehow the thermostat fan got set to manual on. I have went in the menu, and don't see an option for that. So, I guess by unwiring it then wiring it back in, reset it. I had even contacted CPI security, to tell them my thermostat wad messed up.
Thx for everyone's help.
Never really had a problem.
 
 

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