Replaced Outdoor Fan Motor, now the whole system won't come on..

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  #1  
Old 07-27-13, 09:08 AM
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Replaced Outdoor Fan Motor, now the whole system won't come on..

I've got an old Ruud UPKA043JAZ. It had a 3 wire outdoor fan with dual cap which i just replaced with a Grainger universal 5 wire fan adding the MasterFit multi farad cap that came with it. The installation was quite confusing with all of the additional wires and all colors but black being different.

The NEW problem is that when the system is turned on, NOTHING comes on at all. The thermostat clicks as normal, but the air handler and compressor won't come on. I tried unhooking the fan and just leaving the compressor hooked into the dual pole capacitor to see if it would kick on like before, but get nothing. Both circuit breakers (air handler and condenser) did not trip and I reset them just for kicks. Where do I start troubleshooting and what do I look for?? Thank you in advance.

Miles
 
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Old 07-27-13, 09:48 AM
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Welcome to the forums.

I'd start by checking for a 3 or 5 amp fuse on the control board inside the air handler/furnace. You may have shorted the control wiring while in there.
 
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Old 07-27-13, 10:09 AM
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I just went out and checked the circuit breaker on the air handler, and it's fine. I flipped it for giggles anyway... Still nothing. What else should I check? Is there something with the thermostat that would make everything fail?
 
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Old 07-27-13, 10:15 AM
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I'd start by checking for a 3 or 5 amp fuse on the control board inside the air handler/furnace. You may have shorted the control wiring while in there.
Maybe you missed post # 2 posted directly above your last reply.
 
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Old 07-27-13, 11:10 AM
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I never initially went into the air handler. I changed the outside fan on the condenser. But to find what you mentioned I opened it up, and here's what I see inside.

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I don't see a board or any fuses to check in this unit, unless I'm just not understanding what you're telling me. This is an older unit (2003ish). I looked for fuses outside on the condenser and see nothing. Any other suggestions?
 
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Old 07-27-13, 11:22 AM
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You didn't go into the air handler initially but that's where the control voltages come from.

In the picture is the heat strip setup. Be careful......240 VAC in there.

The red circle is where your thermostat and compressor wiring join. The transformer at the orange arrow is what supplies the 24vac to run all the controls. You are going to need to check it for 24vac output. It will have at least four wires.......the white and black would be the high voltage or supply to the transformer and the other two wires would be the 24 vac output.

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I would start there. Also.....that door that you have off may operate a safety switch that you may have to hold in to power up unit.
 

Last edited by PJmax; 07-27-13 at 11:47 AM. Reason: corrected pic address
  #7  
Old 07-27-13, 11:38 AM
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"The red circle is where your thermostat and compressor wiring join. The transformer at the orange arrow is what supplies the 24vac to run all the controls."



Did you mean to supply an edited picture in regards to this?
 
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Old 07-27-13, 11:46 AM
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Near the lower right hand corner of your picture (inside the "box") are two orange wire nuts. To the right of them and just a little lower is the transformer (outside the box). There is another orange wire nut just to the right of the transformer. That's the transformer that Pete was referring to.
 
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Old 07-27-13, 11:48 AM
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Thanks Bob..... picture added in post #8.
 
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Old 07-27-13, 01:46 PM
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I found the transformer. I checked the two high voltage lines and got 118 VAC on each, however the two other lines (I'm assuming low voltage outputs) are reading nil after turning on all breakers and activating the ac via thermostat . Not so much as a relay click or anything happening here. Would that mean the transformer went bad on me? Thank you guys, so far, for your help.
 
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Old 07-27-13, 01:54 PM
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How did you get 118vac on each ?????? You are checking voltage across those two wires......not to ground.
 
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Old 07-27-13, 02:09 PM
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NO ONE checks voltage properly!!!! Who taught all these people how to incorrectly check voltage?!
 
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Old 07-27-13, 02:34 PM
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No-one said to check the voltage across the two wires. With all due respect, I come from the telecom world where we check a lot of our voltages to ground to identify faults in a low voltage circuit and trigger certain circuits to operate them. High voltage isn't my strong suit, which is why I'm here looking for your instruction and help. I didn't come to get flamed for my lack of experience with house electrical. Thank you for the clarification PJmax.
 
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Old 07-27-13, 02:38 PM
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I apologize, I wasn't singling you out.... I was seriously asking the question of why everyone checks for voltage to ground. It has it's place in diagnostics but is not the correct way to check voltage even when checking 120V....
 
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Old 07-27-13, 03:03 PM
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Understood. Now I learned something new . I'm going to check the voltage correctly and the resistance across the transformer to see if it's bad.
 
  #16  
Old 07-27-13, 03:55 PM
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After removing the transformer from the circuit, I've found...

...the low voltage side looks good at 1.6 ohms of resistance across the coil.
...the high voltage side looks to be shot with it showing open across the white/orange (red/black omitted). Is that a valid conclusion to make?

That being said, could something like this be caused by shorting out or error in outside fan motor wiring? Thank you all again for your help thus far...
 
  #17  
Old 07-27-13, 04:17 PM
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It would appear that the primary (high voltage) side of the transformer is open. However, before you disconnected the transformer, did you take an AC voltmeter and check to see if you had any voltage coming out of the transformer (low voltage side)? It should nominally be 24VAC.

For future reference, I would have checked for 24VAC coming out of the transformer first, and if not present, then disconnected the transformer to measure resistance.
 
  #18  
Old 07-27-13, 04:42 PM
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I did actually check to see if voltage was coming out of the 24 volt end, and got nothing. Thank you for verifying that for me. Also, have any of you guys had experience with the Grainger condenser fan motors and MasterFit capacitors? The original fan was hooked up with a dual cap like this:

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These are the instructions attached to the motor leads that I still have a hard time understanding (mine was a 3 line circuit):

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And this is the wiring diagram that I used, and procured from this website:

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Is that diagram consistent with the wiring on the motor leads or should I disregard the motor leads diagram all together? I apologize for this long winded post
 
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Old 07-27-13, 05:19 PM
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If used in a three wire system (what I understood you had), here's how I interpret it should be wired. From the motor leads label, there should be a brown/white striped wire (not used for 3 wire system), a brown wire which should connect to the Fan terminal on the capacitor, a white wire which should connect to the Common terminal on the capacitor, and a Red & Black wire either of which should connect to the T1 terminal on the contactor. Whether you use the Red or Black wire depends upon which speed you want (Black for High, Red for Low speed).
 
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Old 07-27-13, 06:52 PM
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You never actually told us if you found 120 vac on the primary of the transformer.

the high voltage side looks to be shot with it showing open across the white/orange (red/black omitted)
Not quite sure what that means. White and orange are the 120 vac input ? What are the red and black ?

The primary to a transformer usually opens on a power surge. One reason we wanted you to confirm 120vac between the two transformer input leads is to make sure you are getting supply voltage and aren't getting 240 vac there.
 
  #21  
Old 07-27-13, 08:26 PM
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For PJmax: The wires leading to the white and orange wires on the transformer are feeding 240vac as indicated on my DVOM (which is the required voltage across the white and orange leads going into the transformer omitting the red and black inputs as noted by the picture below). The transformer input (across the white/orange wires) is showing as open just as you mentioned from a surge.

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The step-down transformer puts out 24vac regardless of the input voltage when hooked up as noted on the label, right? If the input voltage was 120vac then the white/black combination should be used omitting the red and orange leads. That's the way I've learned it. Let me know if this sounds wrong, and why.

From the looks of it, you're right about a surge of power opening the input. This whole fiasco started with a crazy lightning storm (not uncommon in Florida. Same thing happened to my fan motor last year, but that motor is no longer available or under warranty. Thank you eBay.) I think the subsequent surge when re-initializing the system finished off an already failing transformer.

For Bob14525: Thank you very much for clarifying that for me. I couldn't find anything on the internet about that motor and where the white wire was actually supposed to go, and the red/black wire deal confused me since i don't have a two speed unit :noob:. So would the setup still work with the two capacitor setup I've hooked up and what makes it wrong (this info is just for my own learning)? Again, much appreciated.
 
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Old 07-27-13, 08:33 PM
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You are correct. Your transformer is setup to run on 240 vac. Just wanted to make sure you were actually getting what you were supposed to. I couldn't see the multi-tap in the picture.

I was trying to figure out how your work outside could cause this problem but came up with nothing. Then you mentioned a lightning storm...... that'll do it.

So you'll need to get a 240 vac to 24 vac @ 40va. transformer.
 
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Old 07-28-13, 07:27 AM
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Miles, the way you have it wired is okay. You have it wired as a 4-line circuit, which requires a separate capacitor, which you said you have. If you had wired it as a 3-line circuit, you wouldn't have needed the extra capacitor (assuming the 5mfd side of the dual capacitor was good).

Bob
 
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Old 07-28-13, 10:37 AM
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Ok. So the last two questions, (for now). Your knowledge has been priceless.

First, in the two cap setup, does the white wire (for the universal outdoor fan) still go to the common side of the compressor's capacitor when running two capacitors as Bob suggested before in the dual cap setup?

And secondly, is there a common place that the transformer could be bought besides an A/C supply place? The nearest Grainger is a 50 minute drive for me. I was hoping to get one today (Sunday). Thank you all again for volunteering your time and expertise!! Especially Bob and PJmax
 
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Old 07-28-13, 02:40 PM
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The white wire (common) would always connect to T2 or the C (capacitor) terminal as shown in your diagram. In reality, T2 & C are the same as they are connected to each other. So, it doesn't matter whether the white wire is connected to either the C terminal or the T2 terminal.

Unfortunately, I can't help you with your second question. It's possible that a large hardware store might carry one, and you can buy them on Amazon & eBay (but that would take time for shipping). You might also be able to get one from a local HVAC contractor.

Good luck with your system. Hopefully the new transformer will solve your problem.
 
  #26  
Old 07-29-13, 04:45 PM
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Ok... After replacing the condenser fan, the transformer, and now, the capacitor, everything comes on... EXCEPT the compressor. I hear it hum and stop over and over as the condenser fan runs fine. Before this whole ordeal, it was running without the condenser fan. And after about 30 seconds of trying, the transformer trips (the new one has a circuit breaker on it). Does this mean that my compressor is shot too?! I wish I had the money for a new system, but cash is definitely not a friend of mine right now.
 
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Old 07-29-13, 05:51 PM
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Sorry to hear that your compressor now won't start. You mentioned that you had a lightning strike. Was the compressor running (without the fan) since the lightning strike? I'm concerned that the circuit breaker on the new transformer is tripping. Whether the compressor starts or not, the breaker shouldn't trip. I'm suspicious that there may be a wiring error of some sort, or the transformer & circuit breaker doesn't have a high enough amperage rating. How does the amperage rating on the new transformer compare with the old one, and what is the amperage rating on the circuit breaker?
 
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Old 07-30-13, 06:46 AM
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You were correct about the transformer. The amperage was too high. However, the new capacitor I installed arced on the casing of the unit and all the dielectric fluid leaked out. I suspect that is the reason the compressor was failing to turn on. Off to the parts supplier.
 
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Old 07-30-13, 09:45 AM
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Check to make sure that the new capacitor has the same or higher voltage rating as the original.
 
  #30  
Old 07-30-13, 04:14 PM
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The capacitor apparently shorted out against my brown/white wire that came "uncapped" when i ran the system. I also swapped the transformer for the proper spec'd one I double checked everything. Everything fired up like a dream! The compressor and condenser fan turned on without fuss as well as the air handler, and then... shutdown! What in the world could be wrong now? It's exactly what's been happening when the other transformer would trip it's internal circuit breaker, BUT, this smaller transformer has no circuit breaker. What could make this keep happening?
 
  #31  
Old 07-30-13, 05:10 PM
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Have you looked up towards the sky, is there a black cloud over your house? Seriously, with the system calling for cooling, check to see if you have ~24VAC on the low voltage (coil) side of the contactor. If not, then you'll have to troubleshoot to determine why.

Turn off the power, unhook the wires from the low voltage side of the contactor, and using an multimeter, check the resistance across the coil and from either side of the coil to ground (metal chassis). If that all checks out OK, leave the wires disconnected from the contactor coil and turn the power back on and the thermostat calling for cooling. Check for voltage at the wires. If no voltage, check where the control line (low voltage wiring) comes into the outside unit to see if you have 24VAC. If not, then you'll have to troubleshoot the wiring inside the house.

Is there a fuse somewhere in the 24V circuit? Many systems have them to prevent the transformer from burning out should a short develop in the wiring. I'm still suspicious that something in the low voltage (24V) circuit is drawing too much amperage. Possibly a bad contactor.

Here's something you can try. If you don't have a blown fuse (or you do and you replace it), and with the low voltage wires disconnected from the contactor, you have 24VAC at the wires, try this. With the low voltage wires disconnected, set the thermostat to call for cooling and press in on the contactor to engage it. The compressor and fan should turn on and stay on as long as you keep the contactor engaged. If it runs for several minutes like this (I'm assuming that it was turning off after some number of seconds previously), disengage the contactor and check for 24VAC at the low voltage wires. If you still have voltage, then I'm guessing that there's something wrong with the low voltage (coil) side of the contactor. Either the windings are shorted or there's a short to ground.
 
  #32  
Old 07-30-13, 05:26 PM
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Thank you, Bob. I'll try that tomorrow. Is there also a possibility of my thermostat being at fault? It was acting really strange (wife turning to "cool" and went blank and reset itself. Tried twice more after that) when I reinitialized the system after replacing the condenser fan. Right after that is when I came on this forum with the transformer issue.
 
  #33  
Old 07-30-13, 06:31 PM
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If you want to take the thermostat out of the picture, jumper between terminals RC and Y. This will tell the compressor to turn on. To get the air handler to turn on you would also need to jumper RC to G.
 
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Old 07-30-13, 10:53 PM
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I doubt the thermostat is a causing a short.

You would have been better off with the transformer with the breaker. You need to find out where the current draw is coming from. If you were unsure what to check you would turn the thermostat OFF and see if breaker trips. Then try just FAN ON. Then try COOL. My guess is a defective contactor or a short/bare wire issue out to compressor.
 
  #35  
Old 08-01-13, 09:02 AM
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http://shop.advanceautoparts.com/wcs...0_pri_larg.jpg

Add a fuse system like this to the low voltage side of transformer with a 3 amp fuse and will save trouble shooting this out without burning up the transformer. Don't have a clue why changing the fan motor would cause feedback unless it was a 2 transformer system.
 
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