Ruud Air Handler UBHJ25J11SUZA1 not working - how to troubleshot

[donfagan]

Thanks.  I presume this is not an item I can get at Home Depot, right?  There is an HVAC parts distributor pretty close - is it typically something they'd have in stock or are the breakers for this type of equipment very specialized?

[m_west5]

Hold on. I told you something wrong. Dang distractions. Very sorry. To check the circuit breaker, one lead goes on top and the other on bottom of each side.

With switch on, resistance = 0, good breaker. Infinite resistance = bad breaker.

Both sides need to be good, that is typically how a breaker fails.

[m_west5]

I still believe it is bad by your meter measurments, but please verify before going to the store.

[m_west5]

Home Depot has a really good selection of breakers. There is nothing special about it. Just match exact amps AND pole configuration. Ask for help in the electical dept.

[donfagan]

Pulled the breaker.  With the switch in the on position, the right side (the one with the switch) has 0 resistance, but the left side has infinite.  Guess the left side is the one that's shot.

 

Will go to the store in the am and let you know what happens after I replace it.  Thanks for the help.

[m_west5]

Yep, that's the problem. It was missing the hot, black circuit leg. Cost of a breaker is cheapest repair in an ac system. Awesome!

Yes, let me know. And my pleasure. Thanks for coming to appliantology.org. Please tell your friends about us.

[donfagan]

Well, good news and bad news.

 

I replaced the breaker and there is now 245v on both sides of the breaker.  I also tested further upstream - between various combinations of black and orange wires (M2, M4, M5, an M7 black wires and Blue, Green, Red orange wires) and they have 245v across them as well.

 

But, neither fan nor compressor came on and the tstat display is still weird when I try to turn on the compressor.

 

I went back and checked between the black and orange wire as per your suggestion yesterday and got 0v:

 

>Posted Yesterday, 02:31 PM

>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. 

 

I'm also not getting 24v dc on the other side of the control transformer.  Should I try replacing the CT?  Is it worth trying to replace the tstat, since I have a new one I can try out?  Any way to tell which is the culprit? Is there a way to bypass the tstat and just hard wire the ah to turn on?

Edited August 19, 2014 by donfagan

[m_west5]

Hi donfagan, you said 24 vDc? Is this a typo? Verify your meter setting?

If it is a typo, then I suggest replacing the thermostat first. The erratic voltages as the breaker was failing may have played havoc on the tstat's electronics. Then the next logical step would be the CT.

Did you recently have a brown/blackout or lightning storm?

Let's start there.

Edited August 19, 2014 by beam current

[donfagan]

Well, I thought you had suggested testing for 24v (on the small wires that take the signal from the tstat to the CT), so it's not a typo but possibly the wrong setting.  I must have misunderstood you. Either way, did not get 240v AC across the red and black wires coming from the CT.

 

I am in South Florida, so we have lightning/blackouts/electrical surges all the time.  Could have had one while we were on vacation when the a/h stopped working.

At least one problem - the breaker - is definitely fixed.  Let me try replacing the tstat and see what that does.  Was going to replace it anyway because the new one has wifi/remote programming capabilities and I can return it to Home Depot if I end up not wanting to use it.  If not, will remove the CT.

[donfagan]

OK, so I took apart the current thermostat but did not replace it with a new one.  Basically, it looked like the wiring resembled this configuration from the tstat manual:  https://drive.google.com/file/d/0B4i04vbfPxdjalBRQmFTTUF6LTg/edit?usp=sharing  (top right, circled).

 

I touched the G and RH wires together manually, bypassing the tstat and the fan still did not turn on, nor was there 240v at the orange and black wires.  Is it time to swap out the CT?  Any way to double check that it is the culprit? 

Edited August 19, 2014 by donfagan

[m_west5]

Sorry for the confusion. It can get confusing at times, especially using this method of communication.

Allow me to clarify. All the voltages you are reading will be VAC.

Voltage on the HIGH voltage side of the CT, black and orange = 240 vac.

Voltages on the LOW voltage side of the CT, red and brown = 24 vac.

"did not get 240v AC across the red and black wires coming from the CT."

Please read above statements. You want to measure for 240 vac on the high volge side of the CT black and orange wires. By replacing the known bad circuit breaker, you should have 240vac on the black and orange wires, at the wire nuts. But you state you have 0 volts. Did you check for a possible miswire?

You then want to measure for 24vac on the red and brown wires on the low voltage side of the CT.

If the CT is not getting the proper 240vac INPUT voltage, than it will NOT output the 24vac to power your wall mounted themostat.

Then go read for 24vac on the thermostats base between the red wire and the common wire. Since all tstats manufacturers vary the wire color coding, the common wire color may be blue, brown, white, etc. It's best to check the instruction manual for the existing tstat to see what color the common wire is. If you don't have the instructions, check the base connector for markings.

Power interruptions and surges usually explains the multiple component failures.

[donfagan]

Good news....

 

Found that one of the orange wires was not connected properly to the breaker.  Fixed that and now getting 240v and 24v where they should be on either side of the CT.

 

Need to run out but when come back will put the tstat back together and see if it fires up.  Wish me luck!

[m_west5]

Good job!

[donfagan]

Well, not so fast.  Put everything back together and still doesn't work.  When I turn the fan switch on, I can hear the motor groaning as though it wants to turn but it does not turn.  When I turn the A/C on, the compressor turns on but the fan doesn't turn, and I can hear the same "groaning".

 

Any thoughts?  Is there a capacitor somewhere that could be broken?

Edited August 20, 2014 by donfagan

[m_west5]

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.

 

Are you referring to the outdoor fan motor, in the condenser unit, the mounts right above the compressor?

 

If so, then this is different issue, unrelated to the AH issue. And it has not worked since the beginning?

 

 

So it appears now that we are dealing with multiple failures.

 

 

The best approach is to troubleshoot them one at a time.

 

Let's start with the outside condenser fan.

 

There is a power disconnect mounted in a small box, either mounted on the unit itself or mounted on the wall of your home.

 

Open it and pull the disconnect out. (This only removes the HIGH voltage AC power. The 24vac low voltage power is not isolated, it can still be present on the contactor via the thermostat. So turn the tstat off.)

 

Find the electrical component access panel and remove it.

 

*****Take pictures and mark the wires before removing them.*****

 

There will be either a dual run capacitor, one cap shared by the compressor and fan OR two capacitors, one for the compressor and one for the fan. Either way, they test the same.

 

And remember, capacitors hold a charge even when power is removed from the unit. Mark and remove the wires from the capacitor. Take an insulated handled screwdriver and touch both leads of capacitor at same time for 2-3 seconds for a single run cap.  If it has a dual run cap, touch C to HERM and then C to FAN.

 

This will discharge it, making it safe to handle and to test.

 

Check for a bulging top or any leakage. Obviously, this is bad.

 

Set the meter to the capacitor function. For single cap, one meter lead on each connection. For dual run cap, one lead on C and the other lead to FAN, then C to HERM.

 

The microfarad rating will be printed on the side. 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 %).

 

What reading do you get, in microfarads (uf)?

 

Also check to see if the fan blade turns freely. Should have no resistance. If cap checks good, then you'll need to check fan amp draw and fan voltage.

 

 

Now for the indoor fan.

 

According to the schematic, this is an ICM/ECM variable speed motor. It does not require a capacitor. Since you say it is groaning, it is getting some voltage now, but maybe not the correct voltage and/or all the required voltages.

 

Did you replace the old thermostat with a new one?

 

I would recommend double checking all your wire connections in the AH, especially the fan sequencer and CT. You could also try re-seating both connectors on the fan itself. Switch the AH breaker off first.

Edited August 20, 2014 by beam current

[donfagan]

No, it's the motor on the ah that is not working.  Compressor seems to be working fine.

 

I did not replace the thermostat.  Once I realized that I wasn't getting voltage due to a loose wire, I put the old thermostat back together.  I can try a new thermostat if you think it would help.

 

I did not change any connections in the fan sequencer or CT, but will double check the connections.  Will also try re-seating the motor connections.

[m_west5]

 When I turn the fan switch on, I can hear the motor groaning as though it wants to turn but it does not turn.  When I turn the A/C on, the compressor turns on but the fan doesn't turn, and I can hear the same "groaning".

 

Clarification here. Does the OUTSIDE condenser unit compressor and outdoor fan motor work?

[donfagan]

>Clarification here. Does the OUTSIDE condenser unit compressor and outdoor fan motor work?

 Yes.

[donfagan]

So I checked connections and reseated the connectors to the fan motor.  (I took some videos but waiting for them to upload)

 

1. Turned fan on only -   There is a "groan" every 5-10 secs or so, but the fan never turns on.

 

2.  Turned on AC -  After about 5-10 seconds, the compressor comes on.  The fan makes the "groan" sound every 10 secs or so, then finally comes on around 30 seconds later.

 

 

So, looks like the AC works, though it's back to what was going on a few weeks ago where the fan would turn on after the compressor.  Back then, it would lag by a few minutes sometimes, now it's only about 30 seconds.

 

Thoughts?

Edited August 20, 2014 by donfagan

[donfagan]

Here is the video for the AC:  https://plus.google.com/photos/107780298508392297455/albums/6048515765744550113/6049600731296373938?pid=6049600731296373938&oid=107780298508392297455

 

Here is the video for the Fan only:  https://plus.google.com/photos/107780298508392297455/albums/6048515765744550113/6049600537912075106?pid=6049600537912075106&oid=107780298508392297455

[m_west5]

It definitely sounds like it struggling to start. So would you say we are back to the original pre-failed circuit breaker problem?

The next step would be to put a clamp-on ammeter on the BLACK hot wire that powers the motor. You can measure the amp draw right above the circuit breaker on left side. This will tell you if the motor is drawing excessive current while trying to start. But again, you need to see what the NLA on the motor body sticker says. However, if it drawing some outrageous amps, then it's probably safe to conclude that the motor is bad.

Also check for a voltage drop as the motor is trying to start. Meter to VAC, leads across top of circuit breaker. Is the voltage dropping significantly as the motor is starting? Does it stay at 240 VAC consistently?

Edited August 20, 2014 by beam current

[donfagan]

>It definitely sounds like it struggling to start. So would you say we are back to the original pre-failed circuit breaker problem? 

Yes, exactly.

 

 

I'll check the voltage drop.

 

Don't have a clamp on ammeter but will see if I can check amp draw with my multimeter.

[m_west5]

I don't think you will be able to check the amp draw with that particular meter in the pictures.

If the motor is getting power up to the Molex connector, then it's safe to say your motor is shot.

I consulted an excellent nationwide technical support rep locally, he watched your video, read through the threads and concurs that the motor is bad.

He also stated that the motor and control module (ICM/ECM set-up which has 2 seperate components), will need to be replaced together. Price for replacement will be fairly expensive also. You may want to consider upgrading this old unit, depending on repair estimate.

The component panel will come out to gain access to the fan, you will have to figure that out.

So I believe you have 3 options:

1. Remove the motor yourself and take it to your local HVAC parts house. They will have to find a suitable substitute due to age of the equipment. Your AH does not have a circuit board controller, but the modern ECM fans will. So now you can expect a more difficult installation. Re-wiring, mounting board, etc.

2. Calling in a professional Ruud HVAC contrator to complete the repair.

3. Upgrade this whole system. Crunch your numbers.

What do you think?

[donfagan]

I was kind of afraid of that...

 

I'm guessing my best options are either 1 or 3.  For 1, maybe I can get lucky and find someone who will sell and older style (non-circuit board) motor.  Is re-wiring the motor an option?

 

For #3, I presume I need a pro to do the install since there will be freon involved - is that correct?

[donfagan]

Also, for #3, what specs would I need to use to price out a compatible new model?  I know the motor is 3/4hp and the cabinet is 25".  

 

And thanks also for checking with your Ruud contact.

Edited August 20, 2014 by donfagan