Help with wiring fan motor for A/C condenser


  #1  
Old 04-24-16, 09:21 PM
G
Member
Thread Starter
Join Date: Nov 2015
Location: USA
Posts: 34
Received 0 Votes on 0 Posts
Help with wiring fan motor for A/C condenser

Hi. New here to this forum. Was wondering if could help wiring fan motor for condenser on Trane XL14i (4TWX4042A1000AB). My fan motor died last spring and accidentally replaced OEM 2-speed motor with single speed from Grainger. Did not take any notes or pictures of original wiring for OEM motor. Have ordered another 2-speed motor and am in process of installing. The new fan I have is Century Master Fit Pro model number F48AD76A01 with another p/n at the bottom (FE6001F) that I actually found more information for. I have an extra red wire that is not present on the currently installed single speed motor.

Schematics for my unit, which am attaching along with picture of wiring, DFC, K4, etc.for currently installed single speed motor, show there should be two wires going into K4 of DFC board (CNT02940), red going to normally open and black going to normally closed, however the way it is currently installed based on picture described previously, white wire goes into top of contactor on right and black wire goes into top of contactor on left. Nothing is connected to K4 except for yellow/red wire going over to K2. On the #1 file for schematics, it shows black going to K4 normally closed, red going to normally open on K4, purple going to capacitor, brown going to same capacitor and a ground. Schematic shows 4 wires, not counting the ground, whereas my 2-speed motor I want to install has 5 wires not counting ground (red, black, white, brown, brown with white stripe). I am also attaching picture of schematics attached to 2-speed motor I am trying to install.

Note, my current single speed motor has a brown wire and brown with white stripe wire going to a cap that is just hanging along with the white and black wires described previously going into top of contactor.

I need help on where to put all the wires. I donít know why purple is on the schematic since current motor and new motor I want to install donít have a purple wire, but of course, I donít have my old OEM motor or remember how the wiring was for it. If I could substitute white for purple in the schematics, everything would work out if I put the brown & white stripe wire into the cap along with the brown wire in the schematics since currently installed single speed motor has a brown and a brown and white stripe wire going into a cap.

In addition to the attached files, I also have closeups of K4 on the DFC if needed and have copies of the datasheet for K4. The 2-speed motor schematic shows the red and black wires going to low and high inputs of whatever that box is that is not labeled, suspect this should be K4.

Any references to attachments, pictures, schematics, please see links below. Please let me know if they do not work:
http://imageshack.com/a/img921/2062/x0zbKa.jpg
http://imageshack.com/a/img921/3369/a4GLgz.jpg
http://imageshack.com/a/img923/7327/3R1fsg.jpg
http://imageshack.com/a/img924/8232/Sl4iN5.jpg
http://imageshack.com/a/img923/1984/HQcAvH.jpg
http://imageshack.com/a/img921/5610/wD1hpE.jpg
http://imageshack.com/a/img924/1243/mXgu1m.jpg

Thanks.
 
  #2  
Old 04-25-16, 04:23 AM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,736
Received 50 Votes on 43 Posts
Here is how I would wire it, but it's best to wait until PJMax or Houston chime in to confirm it or suggest a better wiring.

New Motor--------------> Existing Wiring
White ----------------------> Purple
Brown ---------------------> Brown
Red ------------------------> Red
Black ----------------------> Black
Brn/Wht ------------------> No Connection (insulate end of wire)

Note that after you get the motor wired up and it runs, make sure that the direction of rotation is correct. When the fan is running, it should be blowing air out the top of the fan grill. The fan sucks ambient air through the condenser coil, helping to cool the compressor in the process, and gets expelled out the fan (grill) opening. If the fan is turning in the wrong direction, you'll have to change the wiring as noted in the instruction page. Also, make sure that you have the correct capacitor value (7.5 mfd) for your new motor. It may be a different value from what is currently there (previous motor).
 
  #3  
Old 04-25-16, 10:01 AM
G
Member
Thread Starter
Join Date: Nov 2015
Location: USA
Posts: 34
Received 0 Votes on 0 Posts
Thanks. That makes sense substituting the white wire on the new motor for the purple wire of what is in the schematics. Although, currently I have a capacitor just hanging in the electrical compartment of the condenser with a brown wire and a brown with white striped wire going to it, so I would have thought to take the same colored wires from the new motor and connect to the same cap.
 
  #4  
Old 04-25-16, 10:45 AM
Bob14525's Avatar
Member
Join Date: Jun 2013
Location: USA
Posts: 1,736
Received 50 Votes on 43 Posts
Whether the capacitor is "hanging", depends upon whether the motor wired as a 3-wire or 4-wire setup. In your case, your system uses a dual capacitor with a common connection for both the fan capacitor and compressor start capacitor.
 
  #5  
Old 04-25-16, 02:20 PM
G
Member
Thread Starter
Join Date: Nov 2015
Location: USA
Posts: 34
Received 0 Votes on 0 Posts
Okay, thank you very much!
 
  #6  
Old 04-25-16, 04:07 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,536
Received 38 Votes on 34 Posts
I agree with Bob. I would also cap brown with a stripe if you have a good dual cap that is 7.5uF for the Fan terminal on the dual cap.

Hanging capacitors that are not in the control panel are something that I avoid.
 
  #7  
Old 04-26-16, 12:17 PM
G
Member
Thread Starter
Join Date: Nov 2015
Location: USA
Posts: 34
Received 0 Votes on 0 Posts
I installed the new 2-speed condenser fan motor like this: black to normally closed of K4 on DFC, red wire to normally open of K4 on DFC, white wire to common connection or middle connection of 3-way cap they sent me with new motor (cap labeled Century MasterFit APC, has 5, 7.5, 10, 12.5 & 15 MFD options, I connected to 7.5 MFD option), brown wire to brown lead on same cap (one labeled 7.5 MFD), brown with white striped wire insulated on end and not used.

Turned on unit, could hear compressor come on, but fan for condenser never turned on. I reconnected wiring like this: Removed the new 3-way cap altogether, I left the black and red wires connected as described above, I hooked up the white wire from the fan motor to existing run capacitor that came with unit OEM and hooked it up to same lug as red wire which traces back to top of contactor (this matches what schematics for unit show if you substitute my white wire for purple wire in schematics), I connected the brown wire from fan to connection on run cap labeled F for fan, I left the brown with white striped wire insulated and not connected.

When I turned it on, everything worked good, the temperature in house came down from 81 to 75 degrees over about a 3 hour period with the setpoint of thermostat set for 75 degrees, I saw the humidity level on thermostat come down from 60% to mid-50's before I stopped looking at it. Woke up this morning, thermostat showed setpoint 75, actual 77, no or very little air coming out of vents in ceiling, checked condenser, fan was running, but did not sound like compressor was on. Went in attic, saw condensation in various places on air handler, removed filter and looked inside, found A-frame coil assembly completely frozen up with an iceberg. I called an A/C service company as I got to fix this thing and I don't know anything about how they work except I can change out parts and follow schematics, but am in the dark on refrigerant, pressures and all the other stuff associated with HVAC systems.

A little more history on my system, about 6 months ago, the air handler stopped blowing air, measured the windings of its fan motor which all checked out at ~5 ohms each. I ordered a new fan motor electronic control module (ECM) off the internet, installed and worked okay for a few days, then stopped blowing air again, sent ECM back to where I bought it, they said it lost its programming, so they reprogrammed and sent it back, installed and worked for a few days and stopped again. We used electric heaters to get through the tough winter we have here in Texas, but come Spring, the A/C wasn't blowing either, so back to work on it. Sent ECM back to where I bought it, they said it lost its programming again, they reprogrammed it, but said would be the last reprogramming since something else going on with my system. I felt it was a possibility that the single speed condenser fan motor I installed last Spring was maybe sending the wrong signal to the air handler and it was blanking out my ECM programming. I know it is a reach, but either way, I had to try it. At this point, I don't think the reason for my A-frame coils in my air handler freezing up is due to my ECM losing its programming again because I don't remember anything about the coils freezing up in the air handler when I was working the issue of the ECM losing its programming before. Of course, that was during the winter, not the spring.

I am really bummed. At some point I have to stop throwing money and time at my system. Even though it is only 10 years old, I am tired of messing with it. It cost us about $6500. I would really think it should last more than 10 years. If I have to get another one, I am going to be on the lookout for a leading brand that does not say Trane on it.
 
  #8  
Old 04-26-16, 12:55 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Jersey
Posts: 70,055
Received 2,952 Votes on 2,664 Posts
As they push the envelope for higher efficiency the technology gets expensive.
With modern energy saving devices.... the money you save running them gets spent on repairing them. The end user ends up with zero savings.

A lack of airflow thru the evaporator will cause it to ice up. Low on refrigerant can also cause icing.

You're pretty handy..... you could dump the ECM blower motor and convert to a standard multispeed PSC motor.
 
  #9  
Old 04-26-16, 05:10 PM
G
Member
Thread Starter
Join Date: Nov 2015
Location: USA
Posts: 34
Received 0 Votes on 0 Posts
Thanks for the feedback PJMax. I get you on the higher cost of improved efficiency systems.

I paid an $80 service call to a local A/C repair and install company. They are going to order a new air handler fan motor and ECM and also give me a quote for increasing the size of my intake air ducting.

Thanks for the compliment, but I can't keep screwing around with this thing. Got to get it fixed. Thanks.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: