Ruud Air Handler UBHJ25J11SUZA1 not working - how to troubleshot

[donfagan]

I have a Copeland Scroll Compressor Copeland ZR49K3-TFD with a Ruud Air Handler UBHJ25J11SUZA1

 

A few weeks ago, we noticed that it would take a few minutes for the air handler to turn on after the compressor turned on.  Didn't think it was a big deal and did address it.  Last week, we went on vacation with the thermostat set to turn on the A/C periodically. When we came back, we found that the air handler had not turned on at all so the compressor was probably running for a day straight without the cold air circulating through the house.

 

There was a lot of condensation that generated on the coils/pipes and it dripped onto the filter.  Can't see anything else that has been damaged, but maybe also don't know where to look.

 

My question is how to troubleshoot the problem with the air handler?    

 

Today, I turned the on the "fan only" switch on the thermostat and there was a low electrical hum from the air handler, but it would not turn on.  The compressor/air handler are probably 12-15 years old (don't know for sure - they came with the house) but we have 2 other compressor/ah combos in other parts of the house that are the same age but have not had any problems like this one.

 

Any help would be greatly appreciated.

[m_west5]

Hi danfagan,

 

I doubt the condensor unit was damaged.  The evap coil in your AH iced up since the fan was not working.

 

12-15 years is about the time things will start "acting up" in the AH.

You will NEED an ammeter with capacitor testing capability. Sears and Harbor Freight are fairly inexpensive, if you don't already have one. Plus learn how to properly use it before heading up to the attic.
 

I encourage you to read over this several times before attempting this repair.  If you are unsure or not clear on anything, ask before you proceed. There are a lot of good techs here to help.

 

Test the following:

1. Fan motor. Check the amp draw on black wire coming out of fan motor body. NLA (normal load amps) rating is on motor sticker if you can see it. This is the amperage the fan is designed to properly run at. Example: if NLA is 10amps, amp draw on meter will be consistently less than that (7-8 amps). If it pulls 10 or more amps, it will kick off on LRA (locked rotor amps). The fan will be inside a big metal enclosure. Try using an inspection mirror to read the sticker. Note:The fan mount band may be in the way.

Also check for 120vac between black and neutral (white) wires. It needs to stay at 120vac while trying to run. No voltage drop (less than 120vac) while trying to run. The black and neutral wires may be wired to the defrost circuit board. This is where you will take the readings.

 

Watch meter display, values may be displayed very quickly before motor shuts off.

 

*** Check the run capacitor before condemning the fan motor. See #2 below***

 

This is very difficult to change if you have never done it before. Fan wheel alignment is critical. Wiring new motor may be difficult (color coding of wires), access clearance stinks. You'll see when you get into it. Take lots of notes and pictures before you start and mark ALL the wires.

2. Fan motor run capacitor is bad. Check for a bulging top or any leakage. Microfarad rating will be printed on the side. SAFETY NOTE: Capacitors hold a charge even when power is removed from unit. Unplug AH from electrical outlet. Remove wires from capacitor. Take an insulated handled screwdriver and touch both leads of capacitor at same time for 2-3 seconds. This will discharge it, making it safe to handle and to test with your meter. Any value outside of printed rating is bad regardless of what the capacitor looks like. Look for a plus minus percentage factor (5 or 6 %).

3. Circuit board is bad. Your fan may be wired directly off a defrost pcb. Hard to test, but obvious burnt components is what you should look for. But your amp draws and voltage drop testing will tell all.

***Be aware of the safety switch on one of the panels you pull. You will need to push the plunger switch in to energize and test the system components.***

 

***Be aware that all wire connections need to be secure and tight fitting when reassembling everything. Use needle nose pliers to carefully compress any loose connectors. Loose connections create high resistance and heat and will fail eventually.***

 

Your fan motor is the most likely suspect here, and the most expensive. I would discourage you from "shot-gunning" parts. Take a logical, common sense approach to troubleshooting this, because working on this will not be that much fun and you don't want to be climbing in and out of the attic all day either.

 

If the fan motor is bad, replace the capacitor with a new one also. And meter test the new one before installing. It may be bad right out of the box.

This is a dirty hard job, especially in the summer. This will not be a quick fix, so the possibility of heat-related stress should be considered before you attempt this repair. If you have never done this before, I would estimate a minimum of 3-4 hours to complete start to finish for a fan motor replacement, even if you consider yourself mechanically inclined.

 

Hopefully it's the run capacitor that is bad and that job should not take as long, that is, as long as it is easily accessible.

 

You may want to consider contacting a professional to repair instead of DIY'ing it yourself.

Good luck. And remember, safety first. You are going to be dealing with electrical shock hazards, energized moving parts, sharp metal, and heat stress issues, all while working in a hot, cramped, dark and dirty attic.    

 

Plus it's always best to have a buddy help on this type of repair.

Edited August 17, 2014 by beam current

[donfagan]

Thanks - really helpful.  Will give those a try.  

 

Hoping it is just the capacitor - it was probably in the process of going bad during the time when the blower would go on after a few minutes.

 

Silly question, but is the motor and capacitor accessible from only one side of the air handler?  I took off 2 panels that access 2 sets of coils, but the top panel that covers the fan/motor and has the breaker doesn't seem to be removable.  Will I need to somehow pull the entire unit out from the closet in order to get access?  Is there a trick to removing the motor panel?

[m_west5]

Awesome! Most AH's I work on here in AZ are in the attic.  Piece of cake now.

 

No such thing as a silly question. Any appliance can be quite the "engineered marvel".

 

No, there should be no need to pull the entire unit out of the closet.  Then you would be dealing with the sealed system copper line set (pressurized freon).

 

You should just have to remove a couple of screws and pull up on the panel to remove it. If that does not work, then I'll need to see different angle pictures to figure it out.

 

Can you take pictures and post here? You'll have to use a photo sharing site like photo bucket or other similar websites. Samurai posted a good video on how to do this, just search for it in the forums search bar at the top of the home page.

 

A google search revealed no useable documentation with the model number you provided, so I'm not able to "see" what you're referring to. This is not uncommon for any AC units that are 8+ years old. I'll keep looking though.

 

However, all the above steps still apply, minus the "working-in-the-attic" related material.

Edited August 17, 2014 by beam current

[m_west5]

Cycle the circuit breaker to the OFF position first and then remove the evap coil panel. Then try pushing down-pulling out-pulling up the blower motor panel. Or some sort of combination of that.

 

You will probably have to use some force but it will come off. Since no hardware is used to fasten the panel to the enclosure, it is somehow "pressure fitted" onto the enclosure cabinet.

 

Also, do you know if the fan motor is a PSC with capacitor or an ICM/ECM motor?

Edited August 17, 2014 by beam current

[donfagan]

OK, got the panel off - screws were covered up by some duct tape and it was late at night here in ET...

 

The fan and motor spin when I pushed it by hand.  Feels good - no play, so hopefully it's not the motor.

 

 

Here is a picture of the electronics:  

 

https://plus.google.com/photos/107780298508392297455/albums/6048515765744550113?authkey=CLD9l7Ks6K2mOw

(or https://plus.google.com/photos/107780298508392297455/albums/6048515765744550113 if that doesn't work)

 

 

Are the R, G, B devices the capacitors?  The black devices are labled M1, M2, M3, M4 on the right and M5, M6, M7, M8 on the left (you can zoom into the picture to get a better look).

 

The connectors at the top where the orange and black wires clamp onto have some corrosion.  I don't think it would prevent current from passing through, but I can clean them as part of the process.

 

I couldn't find any documentation either - don't know if the fan motor is a PSC with capacitor or an ICM/ECM motor.  Can you tell from the photos?

 

Where to go from here?

 

Thanks again.

[m_west5]

No they are the sheath heater limits (safety devices). The black component in the middle is the heater relay sequencer. The component on the lower left is the control transformer.

 

The limits are not causing the fan issue.  You will have to try getting the panel out to gain access to the fan. Looks like there are 4 screws to remove.

 

Then look to see how the motor will come out. Then find the sticker on the motor. Also check the removed panels for a wiring schematic. This should have all the technical data on it.

 

Thanks for the pics.

Edited August 17, 2014 by beam current

[m_west5]

Do you have a DVOM meter?

Is the schematic sticker on one of the panels? If so, take a picture and post here. This will make it much easier to troubleshoot. Find the hot and neutral wires to the fan. This is where you would check for 120vac and measure the fan motor amp draw.

Yes, clean the corrosion off. Corrosion will reduce/stop current flow. Check all the wire nuts too.

Remember you still have power to the bottom of the circuit breaker, behind those red tabs. Switch the breaker on and see if there is 120vac on the top of the breaker.

These are the first obvious things to check.

[m_west5]

"The component on the lower left is the control transformer."

Sorry, lower right.

[donfagan]

OK, so I pulled all orange and black wires off the top, removed the rust from the contacts, applied a thin layer of lithium grease, and reconnected.  Did not help.

 

I'm having trouble pulling the panel.  Removed the 4 screws as you described, plus 2 more, but it doesn't want to come out.  Think there is something holding it from the center - possibly the screws that are holding the heater relay sequencer in place - ok to remove those to see if that allows the panel to be removed?  Any other suggestions?

 

I do have a digital multimeter, so hopefully that will be useful when I can get to the circuit diagram.

[m_west5]

Yes, it should be ok to pull the fan sequencer. Just mark the wires so you know how to reassemble when the time comes. And take lots of pictures. Try using an inspection mirror to help see what's the panel if you can.

[donfagan]

Still couldn't get the panel off, but did find the electrical diagram and notations on the model number.

 

Photos are here:  https://plus.google.com/photos/107780298508392297455/albums/6048515765744550113  (I took a few of each in case one was not readable.  They are hi res, so you should be able to zoom in very close).

 

 

Re: model number UBHJ-25J11SUZAI, this is what I read:

 

U = model type

B = blower unit

H = air handler

J = "j" series design

25 = 25 inch cabinet

J = 200/240v, single phase, 60Hz

11 = Nominal electric heat in Kw (?)
S = circuit breakers single supply circuit

U = "upflow" front refirigerant connection

B = coil code -->  I can't tell what this designation means

A = has a cleanable filter

I = meets florida installation standards

 

Also, it's a 3/4 hp motor of size "-060" that puts out between 1800-2000cfm

 

Let me know where to connect up the multimeter...

[m_west5]

Coming out of the control transformer (lower right corner) there is a black wire and an orange wire. They are run up to what looks like the orange and white wire nuts. Find these 2 wires in those wire nuts. Cut the zip ties to gain better access.

Turn on unit. Meter set to VAC (volts ac). Backprobe into wirenuts. Ensure good meter lead tip to stripped wire end contact. Should have 240vac. Be careful. Shock hazard.

This verify two things:

1. Control transformer is outputing proper voltage.

2. Fan is getting proper input voltage, if the connection inside wire nut is good.

Edited August 18, 2014 by beam current

[donfagan]

Thanks. 

 

I found the orange and black wires and removed the orange and white wire nuts.  Set the breaker to "on" and set the thermostat to "Fan on".  Set multimeter to 500v AC and connected the probes - got no reading (i.e. 0v).

 

Then a weird thing happened.  I went back to the thermostat and tried to turn on the compressor, which previously had worked.  It did not turn on.  

 

Do you think there is something wrong with the thermostat itself?  I changed the batteries in it but nothing changed.  The lcd readout is doing some wacky things when I try to turn the compressor on, which makes me think it might be the problem.

 

Here are photos of the air handler and the thermostat:  https://plus.google.com/photos/107780298508392297455/albums/6048515765744550113.  

 

Is  there a way in the thermostat to "jump" the wires and manually make the connection to turn on the a/h or compressor (presumably via the set screws?).  It's a White Rogers 1F80-51.  User manual is here: https://drive.google.com/file/d/0B4i04vbfPxdjUFU0Ymh1UHplU2s/edit?usp=sharing

 

I bought a new thermostat from Home Depot the other day - I can swap it out if that would be worthwhile.

 

 

If not the thermostat, what else to try with the a/h?

[m_west5]

Is there a safety switch on any of the panel perimeters on the enclosure cabinet? Check them all. This switch needs to be closed for the unit to turn on. I do not see any on the 2 pictures, but check the coil panels too.  See my previous #2 post above.

 

If no safety switch, then it looks like the control transformer may be the issue. We are narrowing it down now.

 

Use your meter to read VAC, this time on the other side of the transformer.  We want to see 24vac on the red and brown wires.

[m_west5]

Did the motor hum, as you stated before, when you checked for 240vac?

[donfagan]

I don't recall seeing any safety switches, but will double check.  The ah is wedged into a small closet so there is nothing on the outside of the cabinets because the cabinets are literally pressing against the walls of the closet. 

 

Will check the voltage upstream of the control transformer.

 

Re: #2, I still can't find a capacitor - is there one?  If so, where to look?

No, no hum this time, just dead.  Same thing for the compressor - a day or two ago, it turned on even though the fan did not.  This time, nothing.

[m_west5]

No, nothing will be on the outside of the cabinet. Only in the perimeter of the openings where the panels mount to the enclosure cabinet. Look very closely. This is important.

 

The CT outputs 24vac low voltage signal (red wire) to power the thermostat. The batteries only retain your programming schedule. The common (brown wire) needs to be good for the return.  The flakey tstat display and no 240vac IBM output voltage points to a bad CT at this time.  The outside unit will not turn on either.  The CT may be totally shot now. That's why it is important to read for 24vac now.

 

One step at a time.  There are a few more things to check before we condemn the CT.

 

Probably not a PSC with cap. It's more likely an ICM/ECM motor. But by the way it looks now, the CT is most likely suspect, not the fan.  And lots cheaper to replace.  We need to check a few more things though.

Edited August 18, 2014 by beam current

[donfagan]

Just checked voltage.

 

-on the input to the circuit breaker, there is 245v

-everything else downstream of the breaker is 0v.  Measured the two screws that clamp down on the wires where the breaker exits.  Measured a variety of orange/black pairs that come off the breaker.  Measured the red and brown that come off the control transformer.

Checking for 24v now...

[donfagan]

Tested all the small wires for 24v and got nothing.  Basically, I'm not getting any voltage anywhere past the circuit breaker.

 

I looked for safety switch again and did not see anything.  See pics here for the coil cabinets.  I did not remove the secondary covers, but pulled them back to look behind them.  I can remove them if you think it's helpful.   https://plus.google.com/photos/107780298508392297455/albums/6048515765744550113

[m_west5]

OK, so this was one of the things that still needed to be checked.  So what you are saying is that you do not have 240vac on the top of the circuit breaker, with the switch in the on position? The side without the red safety tabs?  If so, then the circuit breaker is bad. Even cheaper yet.

 

You can do a resistance check of the circuit breaker, but you will first need to cycle off the main breaker for this AH in your home's main service panel.

 

Verify NO power (245vac) to bottom of breaker first. Remove wires from breaker. Switch meter to ohms. Place your meter leads across the top of breaker.

 

Switch on = 0 ohms = good.

Switch on = infinite ohms (or more than 5 ohms) = bad.

Edited August 18, 2014 by beam current

[m_west5]

I have a 3pm appointment.  Keep posting. I will try to check when I'm out. Be back around 4:30. Good job.

[donfagan]

>>So what you are saying is that you do not have 240vac on the top of the circuit breaker, with the switch in the on position? The side without the red safety tabs? 

 

That's correct.  

 

I'll try the resistance check across the top of the breaker.  To be clear, should I remove all wires from both the top and the bottom or just the ones from the top?

[donfagan]

Removed the wires from the top of the breaker and measured infinite ohms (no connectivity).  So, is the breaker the culprit?  Would a faulty breaker also cause the compressor not to turn on (via the wires to the thermostat)?  

 

Picture of the breaker is up on the Google Plus site.

Edited August 18, 2014 by donfagan

[m_west5]

That's right. Good job! The CT provides 24 vac power to your tstat on the wall. The tstat then sends the cool on command to the ouside condenser contactor. No power to CT means no power out of CT, nothing works.

Remove breaker from unit and take it with you to get a new on. Match identical amps and pole configuration. Someone at the store will be able to help.