Air Handler troublshooting - Carrier FB4CNF036


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Old 08-22-14, 02:03 PM
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Air Handler troublshooting - Carrier FB4CNF036

Troubleshooting issue (I believe) with my air handler.

Noticed compressor was running continuously, further found evaporator iced over and fan not running at all.

Thermostat controls compressor as desired, just does not turn fan on.

I did some basic troubleshooting but have not been able to isolate issue. I appear to be getting identical voltages at motor regardless of whether thermostat is calling for cooling/fan or not. That said, I have not been able to figure out what I should be getting (or exactly where I should be measuring.

System is a Carrier FB4CNF036 air handler that is fairly new (2011) with a Carrier compressor and Aube TH141 thermostat.

Any help with how to troubleshoot issue (motor, transformer, etc.) given wiring diagram (see attached) would be greatly appreciated.

Thanks in advance.

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Old 08-22-14, 02:19 PM
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I found a manual for your air handler http://dms.hvacpartners.com/docs/100...fancoil-03.pdf. It says that you have an ECM motor. I'm assuming because it's relatively new, that it's an ECM 2.3 motor. I have one in my York furnace and unfortunately, they are notorious for failing. Mine failed after 5 years in the middle of winter. Often, what fails is a thermistor in the motor control unit (bolted to back of motor). If you have an ECM 2.3 motor, you can read more information regarding it in the following thread: http://www.doityourself.com/forum/ai...ble-motor.html
 
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Old 08-22-14, 02:54 PM
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Thanks! 2 quick questions:

1) warranty: my unit is only 3yrs old but was purchased by previous owner. Might I expect this to be under warranty if the motor is indeed bad?

2) motor troubleshooting: in step B on the Fan Motor section says:
Check for proper high voltage and ground at the L,G, and N
connections at the motor. Correct any voltage issue before
proceeding to the next step.
How do I determine what the voltage should be at each pair? Also, I'm assuming I'm testing C-L, C-G, C-N, no?

Thanks in advance.

BTW, I appear to have a Genteq X13 motor (see attached pic).
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Old 08-22-14, 03:13 PM
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The Genteq X13 motor, while similar to the ECM 2.3, is different. Ignore the link I sent you regarding the ECM 2.3 motor.

I don't know what the "proper high voltage" should be, however since the label on the motor indicates that it's 230VAC, I'm guessing that it should be in that range. I assume that the voltage readings at L, G, N are referenced to the common (ground).

As for the warranty, there are two issues. The first is the length of the warranty. I don't know what Carrier's warranty is. In my case, my dealer purchases a 10 year York warranty for every install (included in price). All I had to pay for was the labor for the service call to diagnose the problem. The second issue is (assuming you're within the warranty time frame), whether the warranty is transferable to the second owner.
 
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Old 08-22-14, 06:29 PM
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Okay, so I've confirmed that the inputs to the motor are correct and I'm still getting no response, suggesting the motor is bad. In addition, I've learned that the Genteq X13 is considered a single, sealed unit by the manufacturer thought i have seen ECMs for sale and it looks to be easy to replace w/o the motor itself. That said, I have not tried to determine if motor or ECM are the issue.

I'm heading down the warranty path as even the ECM is pretty pricey. My documentation says that for my situation (home owner, 2nd owner the warranty is good for 5yrs and my motor manufacture date is just under 5yrs. Issue is they indicate contacting installer and I don't know who that was - can't find a sticker anywhere in any of the equipment.

Does anyone know if the manufacturer will honor a warranty direct from a consumer? Or if the warranty situation can he handled by any installer/tech?

Thanks in advance.
Thanks in advance.
 
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Old 08-22-14, 07:17 PM
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It does not need to be the installing company but some companies may shy away from warranty work when they did not install it.

A Carrier factory authorized dealer would be more obligated to perform this warranty repair. You can contact Carrier for a list of dealers in your area.

High voltage is always present to your ECM X13 motor. It is the 24 volt signal from SPT to the motor that starts the motor.

Should look much like this...
 

Last edited by Houston204; 08-22-14 at 07:33 PM.
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Old 08-23-14, 05:45 PM
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Great - thanks, now to find an authorized dealer before the temp spikes on Tues.

My wiring diagram looks much like this (see further down in thread) and I have confirmed low voltage (~28vac in my case) when calling for cooling as well as high voltage.
 
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Old 08-24-14, 09:20 AM
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You can call 1-800-Carrier to get a list of factory authorized dealers in your area.
The motor should be under warranty but labor will not be...

Carrier Contacts, Press, General Inquiries, Customer Support
 
 

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