Fan control center repair or replacement (for AC system)


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Old 05-05-24, 08:50 AM
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Fan control center repair or replacement (for AC system)

Hi,

I have a fan control center for my HVAC system which does not appear to be energizing the contactor on my AC compressor.

I have been unable to identify a replacement for the entire unit (which appears to contain several individual components), or the individual components that make it up.

The part number for the fan control center is 57-01V18BC3E284.

The label indicates the following:
- not to exceed -25A 300 VAC
- relay contacts: N.O. - red/blk
- pri: 120VAC. 50/60Hz. sec: 24VAC. 40VA
- Products Unlimited Corp.

I am attaching a picture of the fan control center, as well as some of its individual components.

Does anyone know what I could buy to replace the entire thing, or even the individual components?

I appreciate your help.

Chris
 

Last edited by PJmax; 05-05-24 at 06:18 PM. Reason: removed un-needed pics
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Old 05-05-24, 02:08 PM
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A fan control center is never used to activate an A/C compressor.
A fan control center is typically used in an oil burner furnace to activate a blower.
We need to know exactly.... 100% what your system is.
Oil burner..... gas furnace.... forced air ..... etc.
 
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Old 05-05-24, 03:00 PM
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Response to Pjmax

Hi PJmax,

Thank you for taking the time to respond.

My HVAC system is an air handler that has an oil burner with an AC coil stacked above it. The burner and air handler cabinet are from 1998 or 1999 (when the house was built). The AC compressor and coil are about 4 or 5 years old.

The outdoor compressor is a Trane model 4TTR6048J1000AA.

The coil is a Trane A coil model 4PXCCU48BS3H.

I am attaching photos of the inside of the air handler (where the burner and other parts are located.
The thermostat installed when those items were replaced is a Honeywell TH6320U2008.

I appreciate your time, help, and patience.
Regards,

Chris











 

Last edited by PJmax; 05-05-24 at 04:35 PM. Reason: resized/labeled pics
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Old 05-05-24, 04:14 PM
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I’m thinking it is the definite purpose contactor on the outside AC condenser.

I believe the problem may be an issue with the definite purpose contactor on the outside AC condenser.

The button is sitting flush with the casing of the contactor when the thermostat is calling for cooling. The condenser fan motor comes on when I push the button in (depress it) when the thermostat is calling for cooling. When I stop pressing the button, the button either:
- immediately pops back out to its flush position and shuts off the condenser fan motor, or;
- stays depressed for a few seconds (running the AC condenser fan motor) and then pops back out and shuts it down.

Does that sound like it could be the cause of my AC not working?

Here is a photo of the definite purpose contactor.


 
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Old 05-05-24, 06:15 PM
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That's too clean to be bad.
Find the thermostat wiring coming out of the house where it connects to the condenser.
Should be two wires. The splice may be inside where the AC wiring connects.
Check for24vac there when the condenser should be running.,

If you have 24vac there.... check for 24v on the blue and yellow wires on the contactor.
You can pull power to the condenser during these tests.

Please read first for A/C repair
 
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Old 05-06-24, 01:18 PM
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Turn off the condenser power.
Set stat to cool. Allow 5 minutes start time.

Check the yellow and blue connections in the white circle.
If you have 24vac there..... check the yellow/red and blue connections on the contactor.
If you have it below and not at contactor..... you are low on refrigerant.
If you have the 24vac at the contactor and it's not closed.... it's bad.

Your incoming yellow wire connects to pressure switch.... not the contactor.
Then there is a red/yellow that connects to the contactor.
 
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Old 05-07-24, 01:46 PM
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Response to TJmax

Hi Tjmax,

I did everything you said to do (turn off power to the condenser, set the thermostat to call for cooling and waited more than 5 minutes).

There was no voltage reading when I checked the blue and red wires coming from the thermostat.

I did not check anything beyond that because, if I am correct, there would be nothing going from there to the pressure switch or contactor.

Am I correct about that?

What does this information point towards as being the cause of the problem?

“Thank you” in advance for your time, help, and patience. I sincerely appreciate it.
 
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Old 05-07-24, 05:39 PM
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You checked blue and "yellow" at the outside condenser and found 0 acv ?

The thermostat and condenser wiring should be spliced at the air handler.
The yellow going outside comes from Y on the thermostat.
The blue going outside comes from C at the air handler.

A picture of the air handler wiring would be helpful.
 
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Old 05-07-24, 08:17 PM
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The fan center relay provides 24V for the cooling circuit via terminals R and C. Do you have 24V at R and C on the fan center transformer? The R and C transformer terminals should connect to the RC and C terminals respectively in the thermostat.
 
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Old 05-08-24, 10:17 AM
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As mentioned..... you can check for 24vac on R and C.
The C is not necessarily connected to the thermostat.
 
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Old 05-09-24, 05:34 PM
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Response

Hi everyone,

I checked in the condenser unit and confirmed there is no voltage at where the blue and yellow wires coming from the air handler connect to the blue and yellow wires in the condenser unit.

The fan center does have slightly over 24V between the R and C terminals.

Pjmax - Here are some pictures of the wiring in the air handler.










 

Last edited by PJmax; 05-09-24 at 07:42 PM. Reason: clarify/modify/label pics
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Old 05-09-24, 07:52 PM
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I removed un-needed pics, resized pics and added labeling so you know what you have.
Some explanations....
Fan center and fan/limit modules labeled.
The fan/limit control operates the blower in heating mode.
The fan center supplies 24vac control power and blower control for A/C.
The W and Y terminals on a fan center are dummies. They are used for splicing only.
That means the yellow wire connected there does absolutely nothing.

The red and white wires on the t'stat are for the oil burner only.
The yellow, orange, blue and green are for the A/C only.

With thermostat removed......
A short or jumper from Rc to G should operate the blower.
A short or jumper from Rc to Y should operate the condenser.
Confirm that.
If it confirms.... the t'stat has a problem.
 
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Old 05-10-24, 02:54 PM
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Response

With the thermostat’s wiring exposed (the digital faceplate off) I used a jumper wire to connect Rc to G, which made the blower fan of the air handler go on. I then removed the jumper wire from G and then connected Rc to Y. Nothing happened.

 
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Old 05-10-24, 03:42 PM
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Additional Response

PJmax - You have been extremely helpful. You are teaching me quite a bit and I appreciate it.

I also appreciate any additional thoughts you might have.
 
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Old 05-10-24, 03:49 PM
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No problem. You supplied pictures that make this easy for me.

Ok.... leave the jumper on Y to Rc and go to the furnace.
There is a yellow splice there. Yellow from stat to fan center and condenser.
Check from Y to C on the fan center.
If yes..... you have a problem between there and the condenser.
Animals have been known to eat thru delicious tasting thermostat cable.
Weed wackers eat cables too.
 
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Old 05-11-24, 08:11 AM
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Response to Pjmax

I put a jumper from Rc to Y on the thermostat.

When I reached the furnace I heard something click and smelled something burning.

There was smoke coming from the top part of the fan center (the part the terminals are attached to).

Did I just destroy my fan center?

Did I just damage my condenser or compressor?

The fan center does look fried. Here are before and after pictures of the back side. You can see the dark areas of the plastic.

If possible, please recommend a compatible replacement part for my system.



Before

After

 

Last edited by chris9th; 05-11-24 at 08:25 AM. Reason: Update
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Old 05-11-24, 09:24 AM
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Update

Now no part of my HVAC works.

The heat (oil burner with forced air) worked this morning. Now it doesn’t.

The breaker for my heater/air handler was tripped. I reset it. Nothing works.

Did I just ruin my entire system?
 
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Old 05-11-24, 12:32 PM
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Ok..... you have a dead short on your Y wire to ground.

The transformer on the fan center is bad.
Since that is not producing 24v... the thermostat won't operate.
You can use any 24v SPDT fan center.
The all serve the same function,. The wiring will look different but I can help you with that.
fan center - supply house
fan center - amazon
 
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Old 05-11-24, 12:37 PM
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I wanted to get the previous info to you now.

You will need to use your meter set to ohms to find out where the dead short is in the yellow wire.
You would break the splice at the furnace and check all 3 yellow wires.
Check from yellow to any ground, furnace frame, etc.

If the short is in the condenser line.... then you need to break the yellow wire at the base of the condenser where the yellow lines connects.

Also sent you a PM.
 
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Old 05-11-24, 01:00 PM
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Are the parts you linked me to at SupplyHouse and Amazon the same? One seems to have a letter “u” At the end.

Does that matter?
 
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Old 05-11-24, 01:12 PM
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When I used a jumper wire to connect Rc to Y I stuck the ends into the holes where Rc and Y are in this picture.

Was that wrong? Would that have caused the short?


 
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Old 05-11-24, 02:14 PM
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I'll clean up the un-needed posts later.
Many parts are sold on amazon and in parts distributors. They add letters to the end to differentiate.

You need a 240v - 24vac coil - 30A - 1 pole contactor with removable wiring screws because you have lugs on the wires. Most of the contactors use setscrew lugs which would mean you would have to cut the lugs off. Both would work though.

Looks like better quality than others- my choice
Same type part - name unknown - quality unknown

 
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Old 05-11-24, 02:44 PM
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I bought the one you recommended. It should come in on Monday.

Should I replace the thermostat, or wait until the parts come in? Would I risk frying the new thermostat if the replacement of the fan center and the condenser’s contactor does not work properly?
 
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Old 05-11-24, 04:22 PM
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You can wait on the thermostat.
It won't hurt anything if it has a problem.

In your travels..... pick up an ATC 3 fuse and fuseholder.
It will go between R on the fan center and the orange wire.
It will protect the transformer from future shorts.

All auto parts stores carry them.
 
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Old 05-13-24, 05:14 PM
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Response to PJmax

Hi Pjmax,

I have the new fan center, contractor for the condenser, and the ATC 3 fuse and fuse holder.

I guess I need to figure out how to wire everything up.

Quick (probably dumb) question: Could a problem with the capacitor in the AC condenser have caused any of the issues I have described, including the short circuit which ruined the fan control center?
 
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Old 05-14-24, 01:32 PM
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No.. the cap could not cause the problem.
Your contactor has a shorted 24v coil.

The contactor is pretty much wire for wire.
L1 and L2 are where the incoming power connects.
All the other wires go on T1 and T2.

We'll need to figure out the fan center.

Mount the new contactor upside down. We need the L connections on the bottom.
Wire it..... wire for wire........


 

Last edited by PJmax; 05-14-24 at 01:52 PM.
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Old 05-17-24, 02:17 AM
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Response to Pjmax

Hi Pjmax,

I apologize for not posting during the past few days. Lots of other things have been on my plate this week and, luckily, the weather has been mild so the HVAC has not been needed. It also turned out I did not have a 3 amp fuse to go with the fuse holder I got from Amazon the other day. I finally got to NAPA yesterday to get some.

Do you think you might be able to help again later this afternoon/early evening so I can get the new parts wired up?

I appreciate your help.
 
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Old 05-19-24, 07:24 AM
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PJmax


After







Before

Before

Before
Before

 

Last edited by chris9th; 05-19-24 at 09:53 AM. Reason: New images
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Old 05-19-24, 04:35 PM
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Problem is apparently fixed ;thanks PJmax)

Thanks PJmax for your help. It is greatly appreciated.
 
 

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