Question about Ruud UBHC Air Conditioner

2 Answers

I am puzzled. Nothing was working with the Ruud unit. The fan was not coming on while setting was set to auto or on. the condenser fan was also not coming on. I traced back to the transfomer and there was no low voltage coming from transfomer though the two legs of 120v were going into the 240v and common leads. I changed the transformer with a 120/208/240 to 24v transformer and saw the same results. I thought well maybe I bought a bad transformer. I picked up a nother transformer from a different manufacture with same configuration. I have good power going into the transformer on the 240 and common. I even took the cover off the transformer to ensure the power was making it all the way to the solder joints. Still no 24v on the low voltage side. Any thoughts?

Posted by on

  • 4 more comments 
  • stormofbrass May 04, 2010

    Thanks for the quick response. I am not next to the system to take pics at the moment that might help. I am testing the short leads coming right off the low voltage side of the transformer. Should I not expect to see an results without a load on the transformer? Also, I did the some knee **** reaction changes first. I changed the t-stat, fan and the relay first. I looked for a fuse before I changed the transformer. I have the wiring scematic about memorized now :) .



  • stormofbrass May 04, 2010

    Just saw this.



    "Let's assume you have no load connected to your transformer. In such a case, no secondary current flows. With no current, you have no voltage drop across those resistive and reactive components of the transformer's secondary side." http://ecmweb.com/mag/electric_basics_tr...







    Duh, I will go to the low voltage components and check the wiring on that side. Would a short to the condenser or tstat also cause this?



    Thanks for your help!





  • stormofbrass May 04, 2010

    Sorry I hope you read this one as my latest response. I meant to say would a cut line (not a short) to the condenser create an open circuit on the low voltage system our would the t-stat continue to function? I will wait for response now. I just responded for tinking throgh my response.



    Thank you, Vaughan



  • stormofbrass May 04, 2010

    As soon as I get a chance, I will check open circuits. I purchased a third transformer just in case and had the same results when I wired it up as well. I am guessing there is a wire cut somewhere. This is my mother in law's unit. She had a lawn person and an electrician out the same day everything went south. The electrician said no way they did anything and I saw that the cable to the condenser was chewed up a bit but did not see an exposed or broken wire. I am going to get a toner and tone out the wires from outside to inside as well. Thank you so much for your help!



  • stormofbrass May 05, 2010






    I traced and checked the continuity of all the secondary cables from the t-stat with the multitester and the 2 going to the condensor from inside to outside with a speak wire tester I have. Everything seems fine. I also double and triple checked the wiring schematic. One thing, I also noticed is that the continuity of all the transformers I have show positive continuity on the two secondary leads (this may be normal). I tested the secondary with everything hooked up to ensure that there was not an open connection while testing and still no or .001 volts. I even took the voltage out from the secondary straight to the relay ensure there was not an open connection and nothing. Still puzzled. Again.... Thanks for any further assistance you can provide.



  • stormofbrass May 05, 2010

    Also, primary and secondary Ohms are reading exaclty 1



×

2 Answers

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Master
  • 674 Answers

You said you have 120 vac but then you say you have it connected to the 240 v and common legs. If you have 120 v going to the transformer you should have it connected to the 120 v and common legs. Before you reconnect the transformer use an ohmmeter and check the secondary winding. It should be more than 1 and probably less than 75 ohms. Also check the primary winding you should get about the same range.

Posted on May 04, 2010

  • 1 more comment 
  • Brian Niten May 04, 2010

    Even if you had a broken wire for one of the other components you would still read 24 vac at the transformer leads.

  • Brian Niten May 05, 2010

    1 ohm seems a little low (120vac/1ohm=120amps). You said you had another transformer, without it being hooked up check the resistance of the primary and secondary windings to see how that compares. Also you didn't say anything about the 120 vac or 240 vac I mentioned in my first post.

  • Brian Niten May 05, 2010

    I've been waiting to hear back from you to see if this helped. Please let me know what you found.

×

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    Genius:

    An expert who has answered 1,000 questions.

  • Master
  • 1,400 Answers

Hello

Something on the low voltage side of the circut is open.This is why your not seeing 24 volts at the transformer.

Is there a low voltage fuse or fuse trip near the transformer.

Check all low voltage systems,t stat, circut board.ect.

Posted on May 04, 2010

  • mpcheesman1
    mpcheesman1 May 04, 2010

    If the condensor fan motor is being controlled by the low voltage speed control or if it has a speed control,then yes an open circut or short could mess things up.





    There may also be a time delay relay that can cause a open circut if its not operating.



    Im assuming youve checked this transformer unwired to the unit? So weve got 120 v and 120 v going in.And nothing coming out.Ground or possible nuetral problem may exist with the incoming power.



    Another thought is the 2nd new transformer is bad right from the box.

×

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

Subzero 611 freezer not cooling


Could be but before that check if settings are working. Set the freezer settings to coolest and see if cools. If ok, set to desired temp.

Dec 30, 2013 | Refrigerators

2 Answers

I have a 15-year old Ruud Achiever 10 A/C unit outside that has blown a second set of fuses in just a month. The fuses are in the box on the wall adjacent to the unit. What may be causing the fuses to...


A BAD RUN CAPACITOR INSIDE THE CONDENSING UNIT ?.SEARCH YOUR AREA FOR FREE CAPACITOR TESTING.OR LOCAL ELECTRIC MOTOR REPAIR.. CHECK THAT FAN SPINS FREE, IF NOT, IT CAN BE OILED .. SEARCH POST ON OILING FAN MOTORS

Jul 26, 2011 | Ruud Matching Split Air Conditioner

1 Answer

Ruud unit the fan will not turn on for the "cool" setting, but will turn on for the "heat" setting, any ideas of potential issues?


Hello, does the outside condensing unit start when the thermostat is set to cool? if so, the relay on the integrated control board is bad and the board must be replaced. If the outside unit does not start then most likely the thermostat is bad.

Mar 21, 2011 | Ruud Heating & Cooling

1 Answer

I do have the Ruud split unit. My drain line was clogged and when I cut the line at the unit alot of water ran out. Could that of caused it to stop working. The fan will come on but I get no response...


Check for some type of float switch in the condensate pan. It will shut down the unit to prevent more condensate but I am not sure if it would still allow the indoor fan to run.

Sep 21, 2010 | Ruud UBHC Air Conditioner

1 Answer

I have a RUUD Achiever 11 and the outside fan does not come on, and house won't cool. Was told I need a condenser unit. Perhaps I'm overly skeptical, but wouldn't replacing the fan be an easier (and less...


depends on the condition of the unit and if the condenser fan motor is the only problem?
whoever told you that you need a condenser he or she needs to tell you why and point out the issues with what you have seems to me.
to answer your question it would be yes to the fan motor vs.condenser

Jul 05, 2009 | Ruud UBHC Air Conditioner

1 Answer

Ho to turn on central AC unit? (Ruud High Efficiency)



This is typical wiring for a 4 wire thermostat

R = Red One Side of 24 volt Transformer
G = Green Blower relay
Y = Yellow Cool Condensing unit
W = White Heat Furnace

Apr 28, 2009 | Ruud Heating & Cooling

1 Answer

Blower fan will not come on when set on Auto in heat mode.


the fan is controlled by a fan center or a stack switch. as burners light and heat up the spring sensor on the bulkhead above burners heats up and turns and a a point energizes the indoor fan if it gets to hot the burners go out on safty. sounds like a fan control is bad tap on them gently and they sometimes break loose but if not then have a pro replace fan control and test heat exchanger.

Oct 24, 2008 | Ruud UBHC Air Conditioner

5 Answers

Ruud achiever 10 seer air conditioner


It sounds like your condenser fan motor may be locked up or the capacitor that helps give the condenser fan motor a kick to get it started may be defective. Try turning your system on and using a long screwdriver try to push the fan blade on the condenser fan motor to see if it will run normally if you give it the starting boost it needs.If it does run at full speed and doesn't over heat or start and then slow down then you probably only need to replace a simple 10-12$ capacitor. If it barely turns, makes an odd humming sound or overheats etc. then you will have to replace the condenser fan motor. This is assuming that the outdoor condenser has the 220v supplied and the 24v supplied to the compressor relay, that the compressor relay is engaged and suppling 220v to the condenser fan motor.

May 28, 2008 | Ruud Matching Split Air Conditioner

Not finding what you are looking for?
Ruud UBHC Air Conditioner Logo

Related Topics:

81 people viewed this question

Ask a Question

Usually answered in minutes!

Top Ruud Heating & Cooling Experts

Donni Steen

Level 3 Expert

659 Answers

Bill Long

Level 3 Expert

587 Answers

Tim Whalen

Level 3 Expert

3072 Answers

Are you a Ruud Heating and Cooling Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...