DIY Home Improvement, Remodeling & Repair Forum > Appliances > HVAC > Cant figure this out! Not getting 24v at the board or thermostat




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Old 03-06-2013, 07:15 PM  
jayrod
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The metal box has a quick disconnect thats not fused. It says "disconnect not fused" right on it. Its 240 volts outside and inside on the air handler. I measured the main wires going into the handler and they measure 240v. I checked the main breaker and it has 240v.



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Old 03-06-2013, 08:04 PM  
keepinitcool
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Get a qualified person to service this unit. Electricity is nothing to mess around with and it will save you from damaging other components of your system and possibly costing you more money in the long run.



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Old 03-07-2013, 06:01 PM  
nealtw
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Originally Posted by keepinitcool View Post
Get a qualified person to service this unit. Electricity is nothing to mess around with and it will save you from damaging other components of your system and possibly costing you more money in the long run.
This may be good advice but kok328 has already determined that the op has some knowledge and is trying to work thru it with him. It is a diy site.
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Old 03-08-2013, 12:20 AM  
wireless
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Bad fuse on the load side of the transformer.

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Old 03-08-2013, 01:58 PM  
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Can we get a inside pic of the cabinet so I can see what I'm doing?
Being able to see is most benefical. Blindfold a tech and ahe will at least be able to feel his way around, we can do neither.

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Old 03-09-2013, 07:22 AM  
jayrod
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Sorry for the late reply It didnt notify me by email like it was and I thought you guys gave up on me. I should be fine working on it. I have fixed it numerous times over the years but this time Im not sure what the problem is. Heres pics of the handler inside the house. If you need more, let me know.

ac-001.jpg   ac-002.jpg   ac-003.jpg   ac-004.jpg   ac-005.jpg  

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Old 03-09-2013, 02:20 PM  
kok328
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Ok, now that I can see what I'm dealing with, I now know that I'm working on an electric furnace not a gas furnance.
Pretty sure you have a multi-tap transformer that takes only 1 of 3 combinations of primary power (120V, 208V or 240V). The secondary power goes directly to the board.
What are you using for primary power (120V, 208V or 240V)?
Also, can't tell if the fan wire is just hanging loose or is attached to the Y2 (second stage cooling).
Can I get a pic of how the primary wires are connected to power?
At this point your saying that you have primary power but, no secondary power and that the transformer from your other unit works in this unit and the unit heats and runs fine with the transformer from the other unit, correct?

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Old 03-09-2013, 02:43 PM  
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Yellow is connected to Y2. The green one is hanging loose because I tried to jump it with R way earlier.

I never tried the transformer from my working unit in this unit for fear of shorting it out and then being stuck with no working units! I tried the transformer from the non working unit in the working unit and that made the working unit non-working, if that makes sense. Really you just had it backwards.

By primary you mean the common? The common plugs into the XformT1 terminal in the above pic. It was unhooked in the picture. When I measure across the XforTt1 terminal and one of the main incoming wires, I get 240V. Wouldnt that mean its losing secondary power somewhere along the way in there? Thanks alot! I'll get another pic soon.

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Old 03-09-2013, 02:45 PM  
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If I measure across XformT1 and any of the wires on the front of the heat sequencer I get 240v as well.

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Old 03-09-2013, 03:53 PM  
kok328
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If the two units are identical, then this will make troubleshooting a breeze.
Are the primary transformer wires in the working unit connected to 120V, 208V or 240V?
What voltage are you readings on the connections on the primary wires for the working unit?
Are the same voltage readings on this unit?



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