ruud electric furnace acting weird

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Old 12-15-13, 02:43 PM
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ruud electric furnace acting weird

Hello everyone.
I have a 13 year old RUUD combo: UPKA-031JAZ heat pump and UBEH-21J18SUNA air handler.
In summer, the air cooling works as it should I must specify.
The heating is the problem. I now changed the thermostat but even with the old thermostat the system was not working properly in winter. From my knowledge, the heat pump should produce heat by reversing a valve (and it's function) basically from cooling to heating. When the temperature outside is above 5*Celsius the heat pump is doing it's job correctly heating up the house as it should no matter what inside temperature the thermostat is asking for. When the temperature outside is going below 5*C, the heat pump is getting covered in ice and for me to make it working again I have to switch it from heat to cool for a good half hour before it starts to heat properly again. When the temperature outside reaches below -5*C (and the heat pump gets locked by the thermostat, the air handler strips use to kick in and all would be fine, heat would come on OK). I was thinking that maybe the valve it's "sticking" when I stumbled on a test in another site like this one. I shorted out the pins on the heat pump board (I don't remember which ones) and the heat pump went into defrosting. When the heat pump goes into defrosting, it makes a very specific noise that I never hear during normal operating hours (I made a habit of popping my head outside and listening to the noises my heat pump makes during different times. I never hear the defrosting noise). After the test, I was thinking I had maybe a bad defrosting board and wanted to buy a new one. I never bought the board because year by year I get more confused on what works and what doesn't...
That was last year. This year, the heat pump worked fine in the beginning (until the temp dropped below -5*C), then it started all. Occasionally turning off the breakers to all the system would bring normal operation on, or only switching the system to cooling for 30 mins and then back to heating. But that doesn't work anymore. Googling my issue, I found information on how to verify deeper into my air handler if all is OK. I turned my heat pump breaker off (it was useless at -25*C anyways) and I let only my air handler to take care of the heating. If the thermostat is asking for 22*C and the indoor temperature is 5 or more degrees lower, the aux heating would come on and blowing about 27-32*C measured at the one blowing register with a thermometer. But this is not working always. Is very intermittent...
I turned the 2 breakers on the furnace off and I opened the panel.
That revealed 2 60 Amps breakers, 5 coils, 5 high temp limiters and 2 heating sequencers (one 42-23116-09 and one 42-23116-07). I measured all for continuity. The coils passed, the limiters passed and the sequencers passed as well with exceptions. I read somewhere that the 24V heating coils for the sequencers should not measure more than 20 ohms in resistance. Mine were 09=60 ohms and the 07=4.5 Kohms. Also, for the voltage test, turning on the furnace and measuring the actual sequencer contacts (once at the breaker turn on and one after approx 3 mins) were giving constant 240V each excepting one. The only way to get my furnace to heat is to have the thermostat set to 3 or more degrees that the room temperature, this way the emergency heat comes on and it heats some (338C measured at the register).
How is this furnace even heating in emergency mode with the faulty sequencers? Do the sequencers need to be replaced? Do the sequencers have anything to do with the fact that the heat pump don't work properly?
I am baffled here, any help would be more than appreciated.
I have some pics if anyone is interested...
Thanks.
 
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Old 12-16-13, 07:07 PM
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I will have to let someone more familiar with the metric system assist you.
 
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Old 12-16-13, 07:12 PM
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conversions

oh, I am sorry, my bad. 1*C=33.8F so all my readings in the post:
+5*C=41F
-5*C=23F
+33*C=91.4F
-25*C=-13F
+22*C=71.6F
+27*C=80.6F
 

Last edited by Houston204; 12-16-13 at 07:32 PM.
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Old 12-16-13, 07:30 PM
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I'd say that you are going to need a new defrost board but you should verify that your outdoor unit coil sensor is attached to the coil. I have seen the mounting clips break.

I will try to find a manual but often have no luck with that brand.

Please keep links to the competition off of our site.
 
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Old 12-16-13, 07:36 PM
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Thanks for the advice, I was going to finally buy one but I needed to confirm it first. What is this sensor you're talking about looking like? Is it a thermistor type like the sensors for the temperature? (like the ones at 10 ohms or so) or it should look different?
 
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Old 12-16-13, 07:43 PM
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It is the size of 7 stacked dimes with a dent in it to help mount to a 3/8 inch copper ubend. It is usually mounted 3 to 5 inches up from the bottom of the outdoor coil. It has 2 wires and it is connected to the defrost control board (defrost timer).




I'm not having much luck with that manual.
 
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Old 12-16-13, 09:03 PM
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I was hoping to find something like this Carrier guide for your unit...



Did you say that you found one?
 
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Old 12-17-13, 04:24 AM
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i have this manual i found on the net

Hi, thanks for your answers, really helpful!
I have this manual that I found while searching the net and it somehow applies to my unit as well (-)PKA: Ruud Install UAKA UAMB 21354 13 pdf free ebook download
...but I don't understand many of the things in there...

...sorry, disregard the first link, here is the correct one:
https://www.acdirect.com/xcart/image...C_20522-23.pdf
 

Last edited by belgiumrom; 12-17-13 at 04:27 AM. Reason: wrong link
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Old 12-22-13, 06:30 PM
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Hmm sounds like the defrost board is good if it went into defrost mode when you shorted the test pins. For sure check the temp sensor if the coil is frozen over it should make so that the board knows to do a defrost cycle. Might have fallen off or the wires cut or something. Look for DFT pin on your defrost board and check it out.
 
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Old 12-24-13, 05:27 PM
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defrost board test pins

thanks for your reply. i read somewhere that if you short the pins the heat pump should go into defrost and stay there even if you release the pins. mine, as soon as i removed the short, the pump went into normal mode. could you confirm please?

thanks
 
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