Carrier model 38ycb030300 a/c unit top fan doesn't spin

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  #1  
Old 01-28-12, 10:18 AM
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Carrier model 38ycb030300 a/c unit top fan doesn't spin

The fan unit on the top of my carrier model 38ycb030300 unit has just recently stopped working. When the thermostat kicks on the fan motor comes on and sounds like its trying to spin the blades but they barely move if at all, even when I try to push them with a stick. When the fan is off however, the fan blades move freely. I've heard this may be something related to a capacitor?
 
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Old 01-28-12, 04:29 PM
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If the fan spins freely with power removed it may only be the capacitor.

Dual capacitors commonly (but not always) swell on top when they fail.

Dual capacitors serve the compressor and fan.
 
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Old 01-29-12, 06:22 AM
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So where can I find the capacitor I need and can someone direct me to a nice write-up on how to change it?
 
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Old 01-29-12, 07:30 AM
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A local appliance store should have it. The internet has many options.

Turn Off Power to the outdoor unit and Wait a few minutes for the cap to bleed down before touching any terminals.

You would need to match the two uF values and voltage of the old cap.

This is a swollen example of a 40uF, 5uF 370VAC dual capacitor.


The cap comes from the factory with 2 yellow wires on C, blue on Herm and a brown wire on Fan. If you have a start kit on your unit you will have an additional wire on Herm and on C.

If the additional hard start kit is an OEM the color codes will match. If it not write down what you have. (I don't like 5,2,1 start kits, if you have one the small tan circle on top of the start cap has probably already popped out).



Your heat pump probably has the corner panel which looks much like this but also has a defrost control.




You can check a cap with the right meter but the meter will cost more than a cap.
 
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Old 01-29-12, 07:45 AM
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If you have an aftermarket universal motor in this unit the wiring may have been changed from the original configuration.




Sears has an inexpensive meter that can check caps, voltage and ohms (an old pic of it)...
 
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Old 01-29-12, 08:47 AM
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thanks alot thats a huge help!
 
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Old 01-29-12, 11:47 AM
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http://www.docs.hvacpartners.com/idc...t/38byc-2w.pdf

That universal motor drawing is only to illustrate the capacitor wiring. The fan motor black leaves the contactor and connects to the defrost control. It leaves the defrost control and connects to the fan motor.

 
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Old 02-01-12, 02:53 PM
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ok so i replaced the capacitor and now the fan motor definitely sounds stronger and louder but the blades still won't spin, even with a little help pushing them a bit. whats my next thing to check?
 
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Old 02-01-12, 04:16 PM
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power to the motor would be the next thing to check, beyond that it sounds like you need a new motor.
 
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Old 02-02-12, 05:29 AM
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How do I go about checking power to the fan motor. If I wired up the capacitor wrong would it do this? Also, if it is indeed the fan motor where is a good place to find another one?
 
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Old 02-03-12, 05:16 PM
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Measure for 240VAC between the yellow wire and the black wire to the fan motor with a demand preset.

The capacitor must be wired correctly for the fan to work.

You can check the ohm readings as well...
Motor wire = color
Common = black
Run = yellow
Start = brown

The strange thing about dual capacitors is that the motor Run (yellow) connects to the capacitor common.

The fan motor start (brown) connects to fan.

The fan motor Common (black) connects to the defrost control board.

 
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Old 02-11-12, 10:01 AM
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Ok so I replaced the capacitor and the problem didn't change. I have no replaced the motor for the fan and that fixed it but I think it also unveiled another issue which perhaps is the cause of the previous fan motor burning out.

I installed the replacement fan motor and turned it all on and immediately it kicked in and sounded good, spun hard, etc. However it will run for 3-5 seconds then kick off for about 10 seconds then kick back on for 3-5 seconds and just continuously cycle like that. I'm pretty sure this is not how it is supposed to behave. Whats going on here?
 
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Old 02-11-12, 10:05 AM
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wired wrong? Or your defrost control is faulty.
 
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Old 02-11-12, 10:23 AM
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How do I find/check the defrost control?
 
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Old 02-12-12, 09:06 AM
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Try running the unit in cooling mode. I know that sounds a little nuts but if it (new condensor fan motor) works just fine you can shut it off quickly and you can look at the defrost control board.

#1 shut off the outdoor disconnect (shotgun fuses or fuse shut off at the unit)

#2 Select cool on T-stat and a lower temperature ( you will hear a click outside at the unit) you may miss click while going back out to the unit.

#3 After "click" replace shotgun fuses at unit and you are running in cool mode.


now does the fan operate continuously at the unit? If so then you are now going to look at the defrost control board. Pull the disconnect again at the unit so you are shutting off the incoming voltage.

It is a printed circuit board with some wires coming out of it and sometimes a blinking light.

There are some terminals that have to be properly wired, including a relay to turn off the condensor fan during the defrost cycle. It also has a selectable defrost pin that according to the schematic posted earlier by someone, (awesome work) can be adjusted to the defrost cycle. IE it will check at intervals of 30, 60, 90 minutes to see if the outdoor coil needs defrost. It also has a test function and your problem sounds a bit like when I test defrost boards. Basically it jumps the cycle ahead like a time-warp to see if the cycle is operating as it should.

see what you can find out.

also are all the wiring connections from the new condensor fan good. IE solid, no burns bare wires where they connect to the contactor?
 
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Old 02-12-12, 09:23 AM
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I put it in cooling mode the way you described and now the fan doesn't kick on at all. What should this tell me?
 
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Old 02-12-12, 09:50 AM
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can you post some pictures of how you wired the new fan motor? Or draw a schematic of how you wired it?

The defrost control is a circuit board located in the outdoor unit. You should have plugged one of the new motor wires into the board. Did you?
 
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Old 02-12-12, 10:28 AM
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ok wiring

You are more than likely looking at a wiring problem.

Did you replace the fan motor with the exact one that was in the unit or on the nameplate?

Did replace the run capacitor during the process?


Did you wire it 3 wire or 4 wire per the excellent photos posted earlier in the thread?

Did you rewire the fan motor exactly as it was before save the 3 or 4 wire process involved?

even a rough schematic of how you rewired it can help.

I advise everyone to take photos, label, tag anything they can to help in the replacement process, I still do it to this day...
 
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Old 02-12-12, 10:31 AM
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good lord i'm having trouble attaching pictures here





 

Last edited by hvactechfw; 02-12-12 at 11:00 AM.
  #20  
Old 02-12-12, 10:45 AM
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ok, you have wired it correctly. It should be the defrost control board. You can verify this by measuring voltage from the yellow wire on the capacitor to the black wire from the fan attached to the defrost control. With the system running verify voltage of 240VAC nominal. IF you dont get that value then check the yellow to the other black wire going to the control board from the contactor for 240VAC.
 
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Old 02-12-12, 10:49 AM
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There are 3 yellow wires on that one post on the capacitor. Which one should I be testing? The one that goes to the fan?
 
  #22  
Old 02-12-12, 10:56 AM
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it does not matter, you could even follow it back to the contactor and test the yellow from there. They all get the same voltage, the post with the three yellow wires is acting like a junction block and providing all wires with the same voltage.
 
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Old 02-12-12, 11:09 AM
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unless i did it wrong (definitely possible) i believe i got a reading of in the range of 233 - 237 measuring both of those points
 
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Old 02-12-12, 01:29 PM
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Unless you did it wrong the fan should be working and staying on unless the motor is bad. Was the motor running the whole time you had voltage there? While the motor is dropping out is when you really need to check the voltage to make sure it stays.
 
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Old 02-12-12, 02:10 PM
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ok its like you said, the voltage is only there when the fan kicks on, when it cuts off the voltage is gone.
 
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Old 02-12-12, 02:11 PM
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are you losing voltage at both points or just on the fan side of the relay?
 
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Old 02-12-12, 02:17 PM
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both i believe. i tested various ways between contactor, defrost control board, and capacitor
 
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Old 02-12-12, 02:18 PM
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did you get an exact new replacement motor and does the MFD rating on the run capacitor match the necessary one for the new motor?

the mfd rating for the capacitor that the motor needs to match should be on the side of the new motor.
 
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Old 02-12-12, 02:21 PM
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the capacitor rating is not the problem if he is losing power.

@mcastleberg - you need to know for sure in order to make an accurate diagnosis. You must verify that you are losing power only on the fan side of the relay or if you are also losing power on the contactor side of the relay.
 
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Old 02-12-12, 02:25 PM
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ok sorry i'm not great at understanding how to test this circuit properly. let me see if i understand:

to test the contactor side of the relay, i should have one point of the multimeter on the contactor and one point on the defrost control board? or on the capacitor?

to test the fan side of the relay i would test between the defrost control board and the capacitor?
 
  #31  
Old 02-12-12, 02:28 PM
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the replacement motor is a used exact replacement for my previous motor. the previous motor wouldn't even start the fan so this used replacement motor is already an improvement...and i'm hoping that indicates that it is good.

i will re-check the MFD rating on the capacitor and motor but i matched those up as well before purchasing.
 
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Old 02-12-12, 02:33 PM
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You are going to test at both black wires leading to the relay on the control board that the red line is going to in the above picture. Yellow from contactor to one black wire and yellow from contactor to other black wire.

FYI you should NEVER buy a used motor and expect it to work properly unless you saw it run before you purchased it.
 
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Old 02-12-12, 02:39 PM
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yeah i'm only getting a reading when the fan kicks on...
 
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Old 02-12-12, 02:40 PM
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on which side?! I need to know to tell you what to check.
 
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Old 02-12-12, 02:43 PM
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i tested both sides a couple times just to be sure, they each did the same thing, 233 volts give or take when the fan was on and then nothing when it kicks off.
 
  #36  
Old 02-12-12, 03:04 PM
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is the contactor plunger pulling in and out? Now I want you to check voltage only at the contactor. 2 wires enter the bottom of the contactor? Measure coltage across the 2 wires on the bottom. Does the voltage stay steady with the unit running? If yes, check the voltage across the 2 terminals on the top of the contactor. If the voltage drops out there then you need to verify voltage (24VAC) acorss the terminals on each side of the contactor, if that is dropping out then you most likely have a low refriegerant situation. Your HP must have a low or high pressure switch that is opening the contactor circuit.
 
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Old 02-12-12, 03:23 PM
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Not sure what to look for with the contactor plunger. I did see a metal piece move with an audible click earlier today, perhaps when I switched it over to cooling mode. I tested what I believe to be the points you described. The bottom 2 points held constant voltage when fan kicked off while the top points did not. Could you describe again which points I need to verify for the 24VAC?

 
  #38  
Old 02-12-12, 03:26 PM
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The points on the sides of the contactor. Looks like brown wire on left side and 2 yellow wires on right side.
 
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Old 02-12-12, 03:28 PM
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Old 02-12-12, 03:33 PM
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I see the points you are talking about. 24 volts and they too lost voltage when the fan cut off.
 
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